Botany Notes PDF

Botany Mondays & Wednesdays Lecture: 8:30-10:00 AM Quezon Hall Room 211 Lab: 10:00 AM-1:00 PM Rizal Hall Room 106 By: Carielle Nicole C. Montilla Teacher: Sir Ryan Odio  Botany...

Botany Mondays & Wednesdays Lecture: 8:30-10:00 AM Quezon Hall Room 211 Lab: 10:00 AM-1:00 PM Rizal Hall Room 106 By: Carielle Nicole C. Montilla Teacher: Sir Ryan Odio  Botany BOTANY so they prefer to grow in dark or shady  Botany is the scientific study of places plants. This definition requires an  If exposed to the sun they will understanding of the concepts “ plants” desiccate (it means to remove and “ scientific study.” moisture, or become completely dry)  Botany starts when the human and eventually die because to being starts to establish & appreciate reproduce they need water or moisture the role of plants in our lives.  Only needs small amounts of light TWO TYPES OF PLANTS for photosynthesis (1) Vascular Plants  Since body is small less sugar is (2) Nonvascular Plants needed VASCULAR PLANTS USES OF PLANTS  These are higher form of plants (1) Source of medicine  Plants have vascular tissues – (2) Source of food xylem and phloem which are a (3) Source of clothing complex system of transport vessels SOURCE OF MEDICINE  Almost all plants are vascular. One  Herbal medicine type of plant that is vascular is flowering plants. NONVASCULAR PLANTS  Nonvascular plants are also known as Bryophytes, and one prime example is moss.  These plants from the name has no vascular tissues, meaning there is no xylem & phloem  One good example are Upas trees  Small (usually only 5-8 cm tall), (Antiaris toxicaria), which are relatives non-vascular, non-woody of the common fig tree, flourish in the  It is small because it has no vascular jungles of Java and some of some tissues to transport nutrients around. neighboring islands  Gametophyte dominates life cycle  It is poisonous from the name itself, has leaf-like, stem-like, & root-like “ toxicara”. This was used by natives parts for poison arrows.  Lacks essential/vegetative organ of  Later on the tree was found to the plants actually treat cancer  Usually in wet habitats because It has a flagellated sperm that require water to reach eggs Made up of simple cells & tissues & no organ  It has no cuticle to protect themself from UV rays (will cause loss of water) BIO 277B. 1  Botany  In the picture are immature poppy capsules that were gashed with a razor  Marijuana in some countries as well blade. is illegal however countries in some  Opium poppy is a drug that was states in the US, Netherlands it is legal banned because of its addictive while others allow for medical nature. purposes only  However, it actually has medicinal The plant itself is not in the wrong, value but the abusive use of it the human itself is in the wrong (addiction) is prohibited by the because they are the ones abusing government. these plants.  Some countries allow the use of opium as long as it is for medicinal purposes while others don’t at all  California coastal redwoods  Tobacco Cigarettes are still legal in (Sequoia sempervirens). Coastal the country despite their addictive redwoods may grow for thousands of nature. This is due to the vast years and some may reach heights of medicinal applications tobacco has nearly 100 meters (330 feet). and the economic impact it will bring.  Red wood tree peculiar because it  Since fully illegalizing tobacco will reaches at least 100m in height. lead to a downturn in the economy, the  So how can water from the ground country decided to go with the scare be transported to the tip of the tree campaign instead. which is at least 100m tall? BIO 277B. 2  Botany SOURCE OF FOOD  When we look at the inner part it is  Caffeine in coffee is one good more complex than the outer parts example however it is addictive when because it is older than the outer parts you over use it like nicotine  As the plants grow older they SOURCE OF CLOTHING become more complex  Cotton for example is very rampant  After cells are produced by in the textile industry meristems, the cells assume various PLANT TISSUES shapes and sizes related to their  Tissues are a group of cells of similar functions as they develop and mature. structure and perform the same  Some tissues consist of only one kind function. of cell, while others may have two to (1) Meristematic Tissues several kinds of cells (2) Simple Tissues (1) Apical Meristems MERISTEMATIC TISSUES (2) Lateral Meristems (3) Intercalary Meristems APICAL MERISTEMS  Apical meristems are meristematic tissues found at, or near, the tips of roots and shoots, which increase in length as the apical meristems produce new cells The increase in length is called Primary growth  Three primary meristems, as well as embryo leaves and buds, develop from apical meristems.  The three primary meristems that give rise to primary tissues are: (1) Protoderm (2) Ground meristems (3) Procambium  Unlike animals, plants have PROTODERM permanent regions of growth called  Give rise to the primary tissue called meristems, or meristematic tissues, the epidermis of the plant where cells actively divide GROUND MERISTEM  Parts of the plant that are very  Gives rise to two primary tissues -- active in cell division due to the the pith & cortex in roots addition of next set of cells to promote PROCAMBIUM growth and development  Produces the primary xylem &  Along the diff stages or points in a phloem, & the vascular cambium planT body LATERAL MERISTEMS BIO 277B. 3  Botany  Grasses and related plants have neither a vascular cambium nor a cork cambium.  Instead, they have apical meristems, and, in the vicinity of nodes (leaf attachment areas), they have other meristematic tissues called  The vascular cambium and cork intercalary cambium, are lateral meristems, which  Present in the base of leaves or produce tissues that increase the girth internodes to increase the size of of roots and stems. leaves  Such growth is termed secondary  If you trim grass today it will grow growth. back tomorrow unlike normal leaves  Responsible for the increase in like gumamela which will retain how diameter / girth of the stem or the you cut it the next day sideways growth of the stem  The three primary meristems  Reason for the difference in girth or produced are like that of apical width of the tree of an acacia, which meristems has lateral meristems that can  Tissue Differentiation increase the diameter of the stem, and Meristem Tissues produced a coconut tree which has no lateral  Protoderm Epidermis meristems thus their stem cannot Ground increase its width only relies on cell  Ground tissues Meristems growth. Primary VASCULAR CAMBIUM  Procambium vascular tissue  Often referred as the cambium  The vascular cambium also has SIMPLE TISUES meristematic capabilities and it acts as (1) Parenchyma secondary meristems to give rise to (2) Collenchyma secondary tissues that primarily (3) Sclerenchyma function in support and conduction. PARENCHYMA  It gives rise to secondary xylem and  Parenchyma tissue is made of phloem. parenchyma cells CORK CAMBIUM Thin walled, pliable walls, irregular in  Epidermis is replaced when the shape & flattened in cells plant is older by the cork beneath it to They are more or less spherical in prevent water from escaping from the shape when they are first produced, body but when all the parenchyma cells  Part of the Periderm or the armour push up against one another, their thin, protecting the plant (outer covering) pliable walls are flattened at the points of contact. INTERCALARY MERISTEMS  Very simple & allow passage of water & minerals BIO 277B. 4  Botany  They mediate short distance transport of materials through a large extensive plasma membrane that could hold numerous molecular pumps COLLENCHYMA  Irregularly shaped, the white part due to the storage of carbohydrates  In root crops like potatoes radishes, carrots. The roots contain a lot of these types of cells and they perform by Black part is the uneven cell wall storing a lot of starch  Collenchyma cells like parenchyma  Promote repair of damaged tissues cells, have living cytoplasm and may (Capable of regeneration) remain alive a long time.  Promotes photosynthesis because  Their walls generally are thicker and may contain chloroplast more uneven in thickness than those of  Can contain chemicals and crystals parenchyma cells that could protect them for herbivores  Collenchyma cells often occur just  Two examples of parenchyma beneath the epidermis tissues:  Typically, they are longer than they (1) Aerenchyma are wide, and their walls are strong. (2) Chlorenchyma  Found in areas with minimal support (3) Glandular Cells Thicker the cell wall the better it is for (4) Transfer Cells support. Thus collenchyma cells are AERENCHYMA better for support compared to  Parenchymal tissue contains gas parenchyma cells  Allows aquatic plants to float on  Found in parts of the plant that need water minimal support: like nodes where  The type of parenchyma tissue with leaves flowers and roots attach extensive connected air spaces  The thin part of the cell wall allows CHLORENCHYMA transport of materials while the thick  Parenchyma cells that contain don’t but provide structural support numerous chloroplasts (as found in instead leaves) SCLERENCHYMA GLANDULAR CELLS  Has thick tough secondary walls that  Secrete nectar, fragrances, is normally impregnated with lignin mucilage, resins, and oils.  Walls are thick enough to not allow  These cells have greater amounts of passage of materials so most dictyosomes and endoplasmic sclerenchyma cells are dead at reticulum with lesser chloroplasts. maturity and function only for support TRANSFER CELLS BIO 277B. 5  Botany  Two forms of sclerenchyma occur:  The transportation of organic (1) Mechanical Sclerenchyma material, water, and minerals up and (2) Conducting Sclerenchyma down the plants is done by the MECHANICAL SCLERENCHYMA complex tissues. Therefore, they are (1) Sclereids also known as the Conducting and (2) Fibers Vascular tissues. SCLEREIDS  Two of the most common example of complex tissues are xylem and phloem tissue EPIDERMIS  Epidermis is a protective layer covering plant organs  Consists primarily of parenchyma or Sclereids in the cross-section of a pear parenchyma-like cell  Also called stone cells  It also often includes specialized  Short & isodiametric; typically dead cells involved in the movement of at maturity water and gases in and out of plants,  When u eat pears the sand-like or secretory glands, various hairs gritty texture are due to sclereids, (trychome), cells in which crystals are avocados on the other hand do not isolated, and others that greatly have sclereids so they are smooth to increase absorptive parts of roots. eat  Since made up of multiple types of FIBERS cells it is complex  Long; most of its types are dead and PERIDERM the others that remain alive are  Bark of woody plants involved in storage.  Mostly cork cells but some may  For strength to support the tree and have parenchyma cells to repair flexibility to allow it to sway in the wind damage without breaking XYLEM  Examples of plants with fibers are  A type of vascular tissue found in Cotton, Abacca, Pineapple, Banana, plants that transport water and etc. dissolved minerals from the roots to CONDUCTING SCLERENCHYMA the rest of the plant while also  These are sclerenchyma cells that providing physical support. have tracheary elements,  Is made up of tracheary  These include tracheids and vessel components, which are specialised elements which can be found in the water-conducting cells. xylem.  Xylem tissue is an important COMPLEX TISSUES component of the "plumbing" and  Consists of more than one type of storage systems of a plant and is the cell which works together as a unit. chief conducting tissue throughout all BIO 277B. 6  Botany organs for water and minerals overlapping with those of other absorbed by the roots tracheids.  Combination of parenchymal cells, PHLOEM fiber (structural support to vessels),  Conduct dissolved floor materials vessels, tracheids (main transport primarily sugar & other dissolved element together w/ vessels) and ray solutes like the xylem but food cells materials instead  is made up of living tissue that actively transports sugars to plant organs such as fruits, flowers, buds, and roots by using turgor pressure and energy in the form of ATP  Phloem tissue conducts dissolved food materials (primarily sugars) produced by photosynthesis throughout the plant  At the right are vessels (bigger)  It is composed mostly of two types while the left shows tracheid of cells without secondary walls. (narrower) SIEVE TUBE  Most plants have vessels because of  The relatively large, more or less their bigger size thus they are able to cylindrical sieve tube members have pump more water narrower. more tapered companion VESSELS cells closely associated with them.  Vessels have vessel elements as its  Made up of sieve tube members main unit and together they form association w/  Long tubes made up of individual companion cells that are there to cells called vessel elements that are provide support open at each end, with bar like strips of  Like vessels are vessel elements wall material extending across the sieve tube has sieve tube members open areas in some instances. TRACHEID  Spiral thickening on the inside wall of a tracheid  Slender compared to vessels  Like vessel elements, are dead at maturity and have relatively thick secondary cell walls,  The picture shows the longnitudinal are tapered at each end, the ends view of part of the phloem of a black locust tree (Robinia pseudoacacia) BIO 277B. 7  Botany  The blue things in the picture are sieve tube members that come together to form a tube like structure called the sieve tube  Surrounding this tube is a bright yellow colored companion cell. The materials that the sieve tube cannot produce is done by companion cells instead VASCULAR BUNDLES  Are both your xylem and phloem GAMETOPHYTE tissues and other smaller stuff like  This is the more dominant stage in vessels, and parenchymal cells mosses because it is the visible stage of  Tracheids since smaller are not plants and the sporophyte is simply common in plants. attached to the gametophytes making ALTERNATION OF GENERATIONS them dependent on this stage for (1) Bryophytes nutrients (2) Angiosperms  This starts from the protonema or BRYOPHYTES protonemata (earliest form of a  AKA Non-vascular plants or mosses gametophyte; thread-like chain of  Made up of parenchyma cells only cells)  They have no true stem, roots, and  The gametes (sex cells) of plants; leaves however they still undergo thus, it is haploid (n) photosynthesis The antheridium Male  Thus, they are considered as lower (1) pouch contains gametophyte forms of plants the sperm cells  There are two generations: The single egg Female (1) Gametophyte (2) cell is in the gametophyte (2) Sporophyte archegonium  Formed using meiosis so genes are mixed together.  When the egg is fertilized, it becomes a zygote BIO 277B. 8  Botany ANGIOSPERM BOTANY AS A SCIENCE  The study of plants, called botany— from three Greek words botanikos (botanical), botane (plant or herb), and boskein (to feed) and the French word botanique (botanical)—appears to have had its origins with Stone Age peoples who tried to modify their surroundings and feed themselves. PLANT CELL GAMETOPHYTE FIBROUS ROOT TAPROOT SIEVE TUBE MEMBERS AND COMPANION CELLS  Some plants have roots that, as well as anchoring and absorbing, store water or food, or perform other specialized functions. BIO 277B. 9  Botany FOUR REGIONS OF THE ROOT STORAGE ROOTS BIO 277B. 10  Botany  The zygote, then, undergoes mitosis ROOTS and becomes an embryo, which will soon develop into a sporophyte SPOROPHYTE  The spore-bearing part of the plant (diploid)  Totally dependent of gametophytes ANGIOSPERMS  Roots anchor plants to the soil  Holds soil and water particles together, which is why plants are essential to prevent soil erosion, especially trees with larger roots  Roots anchor trees firmly in the soil usually through an extensive branching network that constitutes about one- third (⅓) of total dry weight of the plant  Also known as the flowering plants  The roots of most plants do not (vascular) usually extend down into the earth  Similarly, there are two generations: more than 3-5 meters (10-16 feet) (1) Gametophyte  Those of many herbaceous species (2) Sporophyte are confined to the upper 0.6 to 0.9 GAMETOPHYTE meter (2-3 feet)  Unlike mosses, the gametophytes  Besides anchoring plants, roots are totally dependent on the absorb water and minerals in solution sporophyte generation for nutrition and mostly through feeder roots found in protection in flowering plants the upper meter (3.3 ft) of soil.  The gametophytes can be seen as  Some aquatic plants (e.g. the flowers of angiosperms duckweeds and water hyacinths)  Similar to the Bryophytes, the normally produce roots in water gametophyte stage contains the  Epiphytes (non-parasitic plants that “ gametes” of the plants. Therefore, it is grow suspended without direct contact composed of haploid cells. with the ground e.g. orchids) produce SPOROPHYTE aerial roots  Again, this is the diploid stage.  In Angiosperms, the sporophyte generation is the more dominant stage. Since, as mentioned earlier, the gametophyte stage is dependent on the sporophytes.  Flooding may occur due to VEGETATIVE ORGANS OF PLANTS deforestation and converting farms for (1) Roots non-farm uses (residential subdivisions (2) Stem for example) (3) Leaves BIO 277B. 11  Botany  Roots of plants may vary in length ROOT SYSTEMS for denser plants to compensate for the  Two Root Systems structure of the plant (stability to hold it (1) Fibrous in place) (2) Taproot  Typically, the larger the canopy of FIBROUS ROOT SYSTEM trees, the denser roots are.  Also known as the ADVENTITIOUS  Aside from anchoring, roots of and the DIFFUSED root system. plants absorb water and minerals  Made up of several slender roots  However, only young roots are that grow from the stem capable of absorption. Old roots  No taproot or primary root or cannot absorb, instead, they are used radicle since it disappears at maturity for the transport of minerals or  A large number of fine roots of conduction. similar diameter develop from the  These young roots are very delicate adventitious roots and fragile. Thus, they can be damaged  Adventitious roots are those that do during uprooting. This is why some not develop from another root but plants would die after they are develop instead from a stem, leaf, or uprooted. other plant parts.  Young roots are microscopic, TAPROOT SYSTEM meaning they can only be seen under a  Also called as the PRIMARY ROOT dissecting microscope because they system. are small and delicate.  A taproot is a larger root where all HOW ROOTS DEVELOP other secondary or branch roots grow  EMBRYONIC ROOT, also called as  It is only in old age that a plant can the RADICLE, is the first root that have both a taproot system and fibrous emerges from the roof of the seed root system  When a seed germinates, the tiny  Example of plant that have both root root like radicle, a part of the embryo systems: (immature plantlet) within it, grows out (1) Lunok - when it is young it only has and develops into the first root. a taproot. However, as it grows  Fate of dicot and monocot radicles older, modified adventitious roots are different. This is because the radicle emerge from the stem. of monocot plants disappears and (2) Kamote- like lunok it also has a there grows the fibrous or adventitious taproot system. However, the stem roots. Meanwhile, the radicle of dicot would develop adventitious roots plants grows and develops to become to reach for more nutrients. These the taproot. roots would soon develop new root  The radicle may develop into a thick crops (kamotes). tapered taproot, from which thinner branch roots arise, or many adventitious roots may arise from the stem, which is attached to the radicle and continues with it. BIO 277B. 12  Botany ROOT STRUCTURE or MUCIGEN, a digestive substance that could help roots penetrate through hard structures like soil or rocks.  The mucigel also provides a medium favorable to the growth of beneficial bacteria that add to the nitrogen supplies available to the plants REGION OF CELL DIVISION  Very active during mitosis  Where growth take place, specifically apical meristems  In both roots and stems, there are  There are four regions called from three meristematic areas the tip: (1) Protoderm (1) Root Cap (2) Ground meristems (2) Region of Cell Division (3) Region of Elongation (3) Procambium (4) Region of Cell Maturation PROTODERM ROOT CAP  Gives rise to the outer layer  Composed of a thimble-shaped (epidermis) mass of parenchyma cells to provide GROUND MERISTEM covering and protection to the tip of the  Gives rise to two primary tissues -- root because it is young, fragile, and the pith & cortex in roots easily damaged by rocks, soil acidity,  Inside of the protoderm, and bacteria infestation parenchyma cells of the cortex  It is quite large and obvious in some PITH plants, while in others, it is really  Like cortex, made up of invincible parenchyma cells  one of its function is to protect from  Grass roots and monocot plant damage the delicate tissues behind it roots have pith but dicot plants do not. as the young root tip pushes through  These are parenchyma tissues that often angular and abrasive soil are present in the stems of dicot plants particles, and form as a part of the wood  The root cap has no equivalent in  They work to store carbohydrates stems and repair damaged tissues in the  Cells contain an organelle called roots and the stem. dictyosome (golgi apparatus) and this PROCAMBIUM is abundant in the root cap.  Produces the primary xylem &  The dictyosomes of the root cap’s phloem, & the vascular cambium outer cells secrete and release a slimy  Appears as a solid cylinder substance that lodges in the walls and REGION OF ELONGATION eventually passes to the outside  Merges with the apical meristem,  Aside from protection they produce usually extend about 1cm (0.4 inch or mucilaginous lubricant called MUCIGEL less) from the tip of the root BIO 277B. 13  Botany  Only the root and apical meristem  Root Hairs From the epidermis are actually pushing through the soil since no further increase in cell since takes place above the region of elongation  The region where absorption happens sideways  Made up of rectangular-shaped cells  This is the region where cells duplicate their organelles  Cells become efficient in the absorption of minerals before they  The stele or the central core of the mature stem and root of a vascular plant is  If a cambium is present (typically in made up of xylem and the xylem arc dicot plants like trees) however, there (the red circles) and the phloem normally is a gradual increase in girth  Develops a casparian strip through the addition of secondary (typically red after staining) that is a tissues produced by the cambium lignin substance that makes the region  Secondary xylem & phloem increase of maturation water proof so water and the girth and produces wood, for some other nutrients don’t pass plants without, they experience no  However, if the root is not fully lateral growth mature, it will not be fully enclosed with ZONE OF MATURATION a casparian strip. These endodermal  Also called as the “ root hair zone” or cells are called as passage cells the “ region of cell differentiation” (encircled in red).  The large number of hair like  Thus, the picture above shows a delicate protuberances that develop young dicot root (no pith at the center). from many of the epidermal cells give  Suberin layer (impermeable waxy the root hair zone its name. substance) forms the casparian strip  Root hairs are outgrowth in the  Most of the cell are mature, or epidermis differentiate into the various distinctive  Root hairs increase the surface area cell types of the primary tissue in this for absorption. However, the nutrients region will simply be delivered to the area of cell division and elongation.  The difference between secondary roots, fibrous roots, and root hairs grow from pericycles Secondary  (encircles the roots vascular tissue)  The picture above shows a mature Originates from the monocot root because of the presence Fibrous  stem, specifically of a pith at the center (monocot) and it roots parenchyma tissue is fully encircled by the casparian strip. BIO 277B. 14  Botany FOOD STORAGE ROOT  Most roots are for carbohydrate  The picture above on the other hand storage like ube, cassava, carrots, shows a young monocot root. beets, sweet potatoes (ipomoea plant),  The endodermis consists of a single and arrowroot layered cylinder of compactly arranged  This is why arrowroots are used to cells whose primary walls are create flour impregnates WATER STORAGE ROOTS  The core of tissues, referred to collectively as the vascular cylinder lies to the inside of the endodermis  Some plants reserve water to use them when needed like how succulents store water in their leaves  Example: Manroot (Marah), and come members of the pumpkin family (cucurbitaceae) PROPAGATIVE ROOTS  Lying directly against the inner boundary of the endodermis is an important layer of parenchyma tissue known as the pericycle which give rise to secondary roots or lateral/branch roots.  Mother plant roots have suckers  There is no secondary root in running near the soil surface to monocot plants. produce new plants (asexual SPECIALIZED ROOTS reproduction)  Roots can either absorb nutrients or  Example: Cherries, apples, pears anchor plants to the soil. However, other plants may have modified roots to suit their environment. BIO 277B. 15  Botany PNEUMATROPHORES PROP ROOTS  (foreground) of tropical mangroves  Facilitate the exchange of gases in the plant and the environment  Large adventitious roots grow from AERIAL ROOTS the branches or the stem to absorb more water and minerals  Example: Abanyan ficus tree BUTTRESS ROOTS  Also referred as velamen roots  They are typically green and has  Larger roots for support presence of chlorophyll in the roots  Aerial extensions of lateral surface  could also store water because they roots that work to stabilize the tree have a velamen that serves as a especially in shallow saturated soils to waterproof barrier to stop water from resist toppling or being blown over by coming out. This velamen is composed the wind of multiple layers of dead skin cells.  Tall and plate-like because their  One good example are orchids, upperside grows more rapidly than which are epiphytic because they live other parts. attach to branches of trees.  Example: tropical fig tree CONTRACTILE ROOTS PARASITIC ROOTS  Dependent on other plants for nutrients and water  roots that dig deeper to the bottom  Peg-like haustoria that sucks of the soil like water lilies nutrients out of the host plant  The root is fixed firmly to the soil that  Parasitic roots do not kill the host the stem is pulled downward so that despite taking nutrients from them the base of the shoot is at ground level or deeper (in bulbs).  Ex. water lily, corm BIO 277B. 16  Botany MYCORRHIZAE STEM  The word myco stands for Fungus while rrhizae means plants  This is the association of fungi and roots since fungi is a decomposer that makes minerals for the roots to absorb while the plant creates nutrients through photosynthesis to share with the fungi. The stem is an axis while the shoot is  They have a mutualistic relationship the stem with leaves, buds, or flowers because they both benefit  The area, or region (not structure),  Essential to the normal growth and of a stem where a leaf or leaves are development of forest trees attached is called a node, ROOT NODULES  And a stem region between nodes is called an internode.  A leaf usually has a flattened blade, and in most cases is attached to the twig by a stalk called the petiole.  Angle of internode and petiole is called as the axil of the stem which is why flowers growing there is called  Member of legume family axillary. (Fabaceae)  Axillary buds would also grow at the  Form associations with certain soil axil and it could develop into a branch bacteria that result in the production of numerous small swelling or bloom into flowers.  This is a mutualistic relationship PHYLLOTAXY between the roots and nitrogen-fixing  The arrangement of leaves on the bacteria so that plants can absorb stem so that leaves do not shade each nitrates while the bacteria is protected other by the plant. (1) Alternate (2) Opposite (3) Decussate (4) Whorled (5) Spiral Distichous BIO 277B. 17  Botany ALTERNATE SPIRAL  If the leaves are attached to the twig alternately in two rows (alternate distichous) or in a spiral (alternate spiral) around the stem, they are said to be alternate, or alternately arranged.  Leaves are not aligned with their  Only one leaf is present at each nearest neighbor. node,  Leaves located slightly beside one is OPPOSITE immediately above or below it, forming a spiral up to the stem  If the leaves are attached  Most common arrangement that in pairs, they are said to be could involve alternate, opposite and opposite, or oppositely whorled leaves arranged DISTICHOUS  Two leaves per node. WHORLED  If they are in whorls (groups of three or more), their arrangement is whorled.  Leaves are arrange in two (di-) rows  Three or more leaves (-stichies) only. per node  Examples are leaves of corn and DECUSSATE irises. Above are alternate distichous and opposite distichous arrangements. LEAF AND BUNDLE SCARS  Leaves occur in four rows (when looked at the top)  This only occurs in some species  Deciduous trees and shrubs (those with opposite leaves that lose all their leaves annually) characteristically have dormant axillary buds with leaf scars left below them after the leaves fall. BIO 277B. 18  Botany  The remnants of this shed form leaf PROCAMBIUM and bundle scars  A cylinder of strands constituting  Once the leaves fall, a leaf scar is the procambium appears to the formed. Inside, the vascular bundles interior of the protoderm. are scarred (bundle scar) and can only  The procambium produces water- be observed in the microscope. conducting primary xylem cells and  Tiny bundle scars, which mark the food-conducting primary phloem cells. location of the water conducting and GROUND MERISTEM food-conducting tissues, are usually  The remainder of the meristematic visible within the leaf scars. tissue, called ground meristem,  Lenticels are openings in stems like produces two tissues composed of the stomata in leaves which is also in parenchyma cells. charge of the exchange of gases. (1) Pith ORIGIN AND DEVELOPMENT OF STEMS (2) Cortex (1) Protoderm PITH (2) Procambium  The parenchyma tissue in the center (3) Ground Meristem of the stem is the pith. PROTODERM  For stems, it is present in dicot  The outermost of the primary plants but absent in monocot plants. meristems, the protoderm, gives rise  A complete opposite to the roots to the epidermis. wherein monocot roots have a pith but EPIDERMIS dicot roots do not. CORTEX  The other tissue produced by the ground meristem is the cortex.  The cortex may become more extensive than the pith, but in woody plants, it, too, eventually will be crushed and replaced by new tissues produced from within.  Single layer of living parenchyma HERBACEOUS DICOTYLEDONOUS cells.  Although there are exceptions, the epidermis is typically one cell thick and usually becomes coated with a thin, waxy, protective layer, the cuticle  Cutin is the fatty substance to make Cross section of alfalfa (Medicago) stem the wall impermeable to water. This  Herbaceous dicot stems have builds up a pure layer called cuticle. discrete vascular bundles composed of patches of xylem and phloem. BIO 277B. 19  Botany  The vascular bundles are arranged in a cylinder that separates the cortex from the pith,  although in a few plants (e.g., foxgloves), the xylem and the phloem are produced as continuous rings(cylinders) instead of in separate bundles  The procambium produces only This tree was 24 years old when it was cut primary xylem and phloem,  Over a period of years, the result of  But later, a vascular cambium this type of switch between the early arises between these two primary spring and the summer growth is a tissues and adds secondary xylem and series of alternating concentric rings of phloem to the vascular bundles. light and dark cells (Annual Ring). WOODY DICOTYLEDONOUS  However annual rings cannot accurately predict the age of the tree since it would vary depending on the climate of the place. Cross section of young linden (Tilia) stem  In woody plants, however, obvious differences begin to appear as soon as  This older, darker wood at the the vascular cambium and the cork center is called heartwood, cambium develop.  The lighter, still-functioning xylem  The most conspicuous differences closest to the cambium is called involve the secondary xylem, or wood, sapwood. as it is best known.  Except for giving strength and  The xylem that is produced after the support, the heartwood is not of much spring wood, and which has smaller or use to the tree since it can no longer fewer vessel elements and larger conduct materials. numbers of tracheids, is referred to as summer wood. BIO 277B. 20  Botany thus produce no secondary vascular tissues or cork.  This is why this coastal redwood is thriving despite the removal of its  In a typical monocot such as corn, a lower heartwood and a little of its bundle's xylem usually contains two large vessels with several small vessels sapwood.  Sapwood forms at roughly the same between them. rate as heartwood develops, so there is  The phloem consists entirely of sieve always enough "plumbing" for the vital tubes and companion cells, and the entire bundle is surrounded by a conducting functions. sheath of thicker-walled sclerenchyma  While the vascular cambium is producing secondary xylem to the cells. inside, it is also producing secondary phloem to the outside. SPECIALIZED STEM  Stems have nodes, internodes, and axillary buds; these features distinguish them from roots and leaves, which do not have them. (1) Rhizomes  The term bark is usually applied to (2) Runners all the tissues outside the cambium, (3) Stolons including the phloem. (4) Tubers MONOCOT ROOT (5) Bulbs  Most monocots (e.g., grasses, lilies) (6) Corms are herbaceous plants that do not (7) Cladophylls attain great size. (8) Thorn  The stems have neither a vascular (9) Spines cambium nor a cork cambium and (10) Prickles (11) Tendrils BIO 277B. 21  Botany RHIZOMES  Rhizomes are horizontal stems that grow below ground, often near the surface of the soil.  They superficially resemble roots, but close examination will reveal scale  In Irish potato plants, tubers are like leaves and axillary buds at each produced at the tips of stolons. node, at least during some stage of TUBER development, with short to long  For storage (carbohydrates); internodes in between. horizontal like rhizomes  Ex. Ginger  The "eyes" of the potato are actually  In monocot stem the nodes are nodes formed in a spiral around the arranged along the stem it can be seen modified stem. in the ginger thus it is not considered a root. RUNNERS & STOLON  Both are propagative stems  Each eye consists of an axillary bud in the axil of a scale-like leaf, although this leaf is visible only in very young  RUNNERS are horizontal stems that tubers; the small ridges seen on differ from rhizomes in that they grow mature tubers are leaf scars. above ground, generally along the BULB surface; they also have long internodes.  STOLONS are similar to runners but are produced beneath the surface of the ground and tend to grow in different directions but usually not horizontally. *In the book, stolons are simply another  Bulb are short shoots with thick term for runners leaves (onion, daffodils, garlic). BIO 277B. 22  Botany  Bulbs are actually large buds surrounded by numerous fleshy leaves, with a small stem at the lower end.  Adventitious roots grow from the bottom of the stem, but the fleshy leaves comprise the bulk of the bulb tissue, which stores food. Example: Gabi  In onions, the fleshy leaves usually CLADOPHYLLS are surrounded by the scale-like leaf bases of long green, aboveground leaves.  Other plants producing bulbs include lilies, hyacinths, and tulips. CORMS  The stems of butcher's broom plants are flattened and appear leaf like.  Such flattened stems are called cladophylls (or cladodes or phylloclades).  There is a node bearing very small, Gladioluses have corms with fleshy stems and papery leaf scalelike leaves with axillary buds in  Corms resemble bulbs but differ the center of each butcher's broom from them in being composed almost cladophyll. entirely of stem tissue, except for the few papery scale like leaves sparsely covering the outside.  Adventitious roots are produced at the base, and corms, like bulbs, store food.  The feathery appearance of  The crocus and the gladiolus are asparagus is due to numerous small examples of plants that produce cladophylls. corms-like bulb but is more of a storage stem  short, stout, solid, and more or less rounded in shape. It is filled with stored food and grows in a vertical direction  Stems of cacti are also cladophylls. BIO 277B. 23  Botany  Since they have no leaves, they have PRICKLES leaf-like stems instead that flattens and increases areas for photosynthesis  Like in roses, so that lesser water is lost. they have broader bases and is shorter and pointed  a sharp outgrowth from the epidermis or bark TENDRILS Bali-bali stems are also cladophylls THORNS  Extension of the stem to support  Smaller base, longer compared to vines as it climbs spine  Plants like kalabasa (squash) and  a stiff, woody, modified stem with a marguso (bitter gourd) has this type of sharp point modified stem SPINE  Firm, slender, sharp-pointed structure, representing a modified leaf or stipule BIO 277B. 24  Botany LEAVES  Leaves are also responsible for the (1) Function release of O2 in the atmosphere for (2) External Anatomy humans and animals to breathe. (3) Internal Anatomy  In some plants, leaves have become (4) Specialized Leaves adapted for specialized functions. FUNCTION EXTERNAL ANATOMY  Leaves possess a blade or lamina, an edge called the margin of the leaf, the veins (vascular bundles), a petiole, and two appendages at the base of the petiole called the stipules (small leaf- lie structure at the base of the petiole).  Leaves are the solar energy and CO2 collectors of plants.  Aborbing CO2 is important because this greenhouse gas traps heat in out atmosphere causing global warming  Leaves are involved in photosynthesis  Leaves produce carbohydrates which is why when it is eaten by  Plants with stipule are called as animals they gain carbohydrates like stipulate and plants without stipules when we eat bread or rice. are called exstipulate BIO 277B. 25  Botany  The midrib is the main vein. The petiole connects the leaf to the stem and is also known as the stalk  Plants with petioles are called Poplar’ s Single leaf petiolate while those without are called COMPOUND sessile  Blade divided into leaflets, leaflets  The base is the portion of the leaf lack an axillary bud but each where the petiole attaches (like how compound leaf has a single bud at the nodes is where the petiole attach in the base of its petiole stem)  leaflets are the division of the blade  The tip or the apex of the leaf is its  There are two types of compound top most part leaves:  The margin is the sides of the leaf (1) Pinnately Compound (1) Leaf Types (2) Palmately Compound (2) Venation PINNATELY COMPOUND LEAF TYPES (1) Simple (2) Compound (3) Peltate (4) Perfoliate SIMPLE  Undivided blade with a single  Leaflets in pairs and attached along axillary bud at the base of its petiole. a central rachis (central vein where leaflets attach)  Examples: ash, walnut, pecan, and rose BIO 277B. 26  Botany  Examples: buckeye, horse chestnut, hemp or marijuana, and shamrock. PELTATE  Two types:  Petioles that are attached to the (1) ODD  The middle of the blade. We call this top/terminal leaflet terminal attachment because it is at is only one the top of the petiole  The picture  A simple leaf since there are no above is an leaflets as it is not completely divided example  Examples include Mayapple (2) EVEN  It has two PERFOLIATE terminal leaflets PALMATELY COMPOUND  Sessile leaves that surround and are pierced by stems  Examples include yellow-wort and thoroughwort VENATION  Arrangement of veins in a leaf (1) Netted-venation (2) Parallel venation (3) Dichotomous venation  Leaflets attached at the same NETTED-VENATION point at the end of the petiole  Also known as Reticulate Venation  Same attachment of leaflets  One or a few prominent midveins  The central point is called the from which smaller minor veins branch into a meshed network central rachis  Common to dicots and some nonflowering plants. BIO 277B. 27  Botany  Two types: DICHOTOMOUS VENATION (1) Pinnately-veined leaves (2) Palmately-veined leaves PINNATELY-VEINED LEAVES  No midrib or large veins  A combination of netted and parallel venation  Rather individual veins have a  A single main vein called midrib tendency to fork evenly from the base with secondary veins branching from it of the blade to the opposite margin,  Example: elm creating a fan-shaped leaf (e.g., PALMATELY-VEINED LEAVES Gingko). INTERNAL ANATOMY  In the upper epidermis, there is  Veins radiate out of base of blade lesser stomata because it is mostly for  There is multiple main veins collecting light energy from the sun  Example: maple  Palisade parenchyma is filled with PARALLEL VENATION photosynthetic cells (chlorophyll)  Spongy parenchyma is where gaps in between cells are present for the exchange of gases  Characteristics of many monocots like grasses, cereal grains  Veins are parallel to one another  There are several veins of the same size  No midrib or main veins  The midrip and veins are actually the vascular bundle where xylem and phloem tissues are found. Surrounding the midrib is the bundle sheath cells BIO 277B. 28  Botany  Longitudinal section through a leaf axil, showing the abscission zone in the petiole and the axillary bud just above  The xylem and phloem are not interrupted until the leaf actually falls away  At the leaf base, usually in the petiole, is an abscission zone oriented perpendicular to the petiole  Its cells are involved in cutting off the leaf when its useful life is over  Adjacent undamaged cells swell and become corky, forming protective scar  The trichomes prevent water loss by tissue, the leaf scar, across the wound. increasing leaf-air boundary  Without an abscission zone, dead resistance. Water loss through the leaves might tear off irregularly, epidermis is called transpiration leaving an open wound vulnerable to pathogens. SPECIALIZED LEAF (1) Bulb (2) Leaf Tendril (3) Leaf Spine (4) Leaf scales (5) Leaflet hook (6) Cotyledons (7) Needle (8) Bracts (9) Carnivorous Leaves BULB  Storage leaves that do not undergo photosynthesis  Example: Onion BIO 277B. 29  Botany LEAF TENDRIL  Unlike photosynthetic leaves, tendrils grow indefinitely and contain cells that are capable of sensing contact with an object.  When the tendril touches something, the side facing the object stops growing but  Above are different climbing the other side continues to structures, the terminal tendrils are elongate, causing the tendril to coil leaf tendrils while those growing around the object from the axil is the stem tendril and use it for support. LEAF SPINE  Lamina would be detrimental, and none forms. Whereas many foliage leaves sense the direction of sunlight and reorient the lamina for maximum photosynthesis, tendrils respond by sensing solid objects and growing  Cactus spines are modified leaves of around them. axillary buds.  The succulent, moist cactus body  no leaf blade, and whereas would be an excellent source of water foliage leaves stop growing after for animals were it not for the they reach a specific size, this protective spines. Their needle shape tendril continues to grow protects the plant from herbivores. BIO 277B. 30  Botany LEAF SCALES  During germination, the cotyledon acts as digestive or absorptive tissue. NEEDLE  Small, flat, scale-like leaves form a shield-like covering on stems of junipers, cypresses (Cupressus), arborvitae (Thuja), and others.  This allows the bud to lessen water  Needles, either short or long, occur loss. in all pines, firs, and spruces LEAFLET HOOK  It reduces water loss however, it also has lesser surface area for photosynthesis BRACTS  Similar to tendrils in the stem but they grow from the compound leaves  Certain plants produce clusters of COTYLEDONS tiny flowers and rather than making sepals for each flower, they just make one set of large bracts that protects the entire cluster; these flowers lack sepals  Bracts are colored leaves that looks like a petal for apetalous flowers to attract pollinators  Examples are poinsettia and bougainvillea  Cotyledons are embryonic leaves that store starch and protein. BIO 277B. 31  Botany CARNIVOROUS LEAVES  The ability to trap and digest insects has evolved in several families.  Insectivory has evolved in plants that grow in habitats poor in nitrates and ammonia; by digesting insects, plants obtain the nitrogen they need for their amino acids and nucleotides PITCHER PLANT  secretes chemicals to attract insects and they would die once they reach the water BIO 277B. 32  Botany REPRODUCTIVE ORGANS OF PLANTS expenditure of energy is not used to (1) Flowers nurture the seed which is why we do (2) Seeds not see gumamela fruits. FLOWERS  Also called as bloom or blossom  Reproductive structure in flowering plants (angiosperms or phylum magnoliophyta) which is the most common type of plant.  Although flowers provide aesthetic value to the plant, it main purpose is to reproduce and propagate it species  Cuttings is one example of asexual  Some flowers may not be obvious reproduction. The mother plant always like those of gumamela, but still re have the best characteristics which is flowering plants like crotons, grass, and why it is not typically sold. bamboo.  Flowers mediate the union of male sperm with female ovum in order to produce seeds.  Two types of reproduction: SEXUAL ASEXUAL  In need of male  less  Alugbati is typically propagated and female parts adaptation asexually because its seed are too  more diversity as because no small but it can also be propagated it combines the diversity; the sexually. genes of mother & daughter plant father but needs is exactly the more ATP/ energy same as the  It begins with mother plant pollination, then  easier to fertilization, leading propagate and to the formation and requires less dispersal of the energy from  Tangkong is another plant that can seeds. the plant reproduce both sexually and asexually.  Fun fact: Gumamelas could actually If you uproot it and throw it on soil it reproduce sexually in other countries will grow, and if it is simply left alone, it like Thailand and Taiwan, and will still grow because it can produce produces an “ okra-like” fruit since it seeds. does have an ovary. However, it has been propagated so much in our country that it has started to rely in asexual reproduction. So, the BIO 277B. 33  Botany petals with attractive scents which is why flowers are showy or in bright colors. TYPES OF FLOWERS (1) Solitary flowers (2) Inflorescence flowers SOLITARY FLOWERS  Underground orchids were found in Australia by a farmer after digging.  This flower produce seeds and reproduces sexually  The flower is intact  Example: Gumamela INFLORESCENCE  The Rafflesia flower is the most foul- smelling flower that smells rotten like a dead rat or animal.  The smell is to repel humans from  The flower is divided into multiple picking its flowers while attracting florets insects like flies for pollination  While both solitary and inflorescence flowers have peduncles only inflorescene has pedicels  Example: Santan, Butterfly Orchid COMPOSITE FLOWERS  We mostly admire flowers for their  Species that have more than one aesthetic value but it is for pollinators flower on an axis so-called composite not us, humans. flowers  Insects like bees and butterflies  Also refers to the arrangement of typically are more attracted to colorful flowers on a stem BIO 277B. 34  Botany  It is basically tiny florets together  stalk of each flower (in both solitary that look like they are one flower & inflorescence)  For example, daisy and a sunflower  Labelled as stem in the picture is not a flower but a flowerhead above composed of numerous tiny flowers or PEDICEL florets.  Stalk of each floret in inflorescence RECEPTACLE  Functions for the support of the ovary and other parts SEPALS PARTS OF THE FLOWER  Typically these are green, but are petal-like in some species  A group of sepals or outer whorl of (1) Non-reproductive parts sepals is called a calyx (2) Reproductive Parts PETALS NON-REPRODUCTIVE PARTS (1) Peduncle (2) Pedicel (3) Receptacle (4) Sepal (5) Petal (6) Perianth  Usually, thin, soft and colored to PEDUNCLE attract insects that help the process of pollination.  A group of petals, or whorl of petals is called the corolla BIO 277B. 35  Botany PERIANTH PISTIL  Both the sepals and the petals REPRODUCTIVE PARTS (1) Stamen  The female part of the flower (2) Pistil  The collective term for pistils (one or STAMEN more pistils) is gynoecium (from Greek gynaikos oikia: woman's house)  Comprises the stigma, style, ovary, and ovule.  Male part of the flower  It comprises the Anther and  A pistil may consist of a number of Filament carpels merged together (3rd). Then it  The one or two whorls of stamens is is syncarpous androecium (from Greek andros oikia:  If there is only one pistil to each man's house) flower, or of multiple individual carpels ANTHER that are not conjoined like the 2nd, the  Also called the pollen sack at it is flower is then called apocarpous. where pollen grains are produced  If there is one carpel and one pistil, it  Pollen grains eventually germinate is monocarpous to become sperm  Classification of fruits may vary  Pollen contains male gametes depending on the flower it originated FILAMENT from  The stalk of the anther Consists of parts  Each filament is topped by an  CARPEL like ovary, anther stigma, style Consists of one  PISTIL or more carpels STIGMA  This is where pollen grains land  Sticky part at the tip of the pistil, where nectar is produced to facilitate BIO 277B. 36  Botany the pollination by insects, is the OVARY receptor of pollen  The chemical composition and pH levels of nectar for every species vary to make sure that only pollen grains of that specific species of that plant can germinate and become a sperm cell  Pollen grains require a specific nectar composition to make sure that  The ovary can either be superior or no pollination across other species will inferior occur  It is superior if the stamen is  This is why if corn pollens fall on the attached at the base of the ovary (I is stigma of the corn, it will not superior) germinate, because of the difference of  It is inferior if the stamen is their compatibility barriers attached at the top of the ovary (III is  It is also possible for them to superior) germinate to a pollen tube but once  II is half inferior ovary. proteins on the surface of the tube OVULE matches the incompatibility gene, the  The immature seed stigma and style will block further  Contains the female gametes growth. Thus, no fertilization happens. CLASSIFICATION OF PLANTS BASE ON  Stigma is very important as it is THEIR LIFE CYCLE responsible for germination  One life cycle is when it grows from  Once pollen grains germinate, they a seed and can bear flowers and fruits produce a pollen tube which travels (1) Annual through the style, and enters the ovule (2) Biennials to release two sperm cells which will (3) Perennials fuse with the ovule to form a seed. ANNUAL STYLE  The cycle is completed in a single  Connects the stigma to the ovary season and ends with the death of the  For fertilization to happen the pollen parent plant. (3-4 months) grains must pass through the style  For seasonal plant like watermelon, before going to the ovary egg plant  The supportive stalk of the stigma BIENNIALS which becomes the pathway for pollen  Two growing seasons to complete a tubes to grow from pollen grains cycle adhering to the stigma to the ovules  Can grow in summer and rainy which carry the female reproductive season material  Banana grows all throughout the year, rainy season and summer BIO 277B. 37  Botany  Once they bear fruit, flowers bloom  Many Viola and some Salvia species again and would bear fruit all over are known to have these types of again. flowers. PERENNIALS ENTOMOPHILOUS  Take several or many growing  Attract and use insects, bats, birds seasons to go from a germinated seed or other animals to transfer pollen to a plant producing new seeds. from one flower to the next  Common for fruit tress because it  Commonly have glands called takes them several years to grow and nectaries on their various parts that develop attract these animals. CLASSIFICATION OF FLOWERS BASED  Flowers also attract pollinators by ON POLLINATORS scent and color. Still other flowers use  Each flower has a specific design fo mimicry to attract pollinators.  Structure of the flower depends on the pollinator it engage with  If insects are the pollinators, then it has to be colorful to attract insects. These plant really need pollinators for pollination to take place  The design of the flower depends on  Some species of orchids, for the pollinator example, produce flowers resembling (1) Cleistogamous female bees in color, shape, and scent. (2) Entomophilous  Flowers are also specialized in (3) Anemophilous * Entomophilous and Anemophilous are shape and have an arrangement of the chasmogamous plants which means that stamens that ensures that pollen pollination happens across flowers grains are transferred to the bodies of CLEISTOGAMOUS the pollinator when it lands in search of its attractant (such as nectar, pollen, or a mate).  Self-pollinating flowers, after which, they may or may not open  The perianth is closed to ensure that pollen produced from within the flower  As you can see in the picture above pollinates only the stigma/s of that the bee is surrounded with pollens that flower tend to be large grained, sticky and rich in protein (as a reward for pollinators) BIO 277B. 38  Botany ANEMOPHILOUS some are separated on each plant  Do not depend on insects for producing a male flower bearing pant fertilization but only depend on wind to and a female flower bearing plant. move pollen from one flower to the Similar to kalabasa. next  Common among the family for birch trees, ragweed, maples, and grasses like corn, rice, wheat, & bamboo  They have no need to attract pollinators and therefore tend not to be "showy" flowers, meaning their flowers are neither colorful nor big. They also  In rice on the other hand, has both produce less nectar. female and male parts on one flower  Pollen grains in these flowers are or floret, but it is also an anemophilous usually mall & light to be easily flower. transferred by means of wind FERTILIZATION PROCESS  Their pollens also have little nutritional value because it does not need insects  Male and female reproductive organs are generally found in separate flowers, the male flowers having a number of long filaments terminating in exposed stamens, and the female flowers having long, feather-like stigmas.  Meiosis happens since it makes sure that every sperm cell is haploid  Pollen then lands on the stigma & it germinates by creating a pollen tube as it travel down the style to connect it to the egg to fertilize it will sperm. Once  This is similar to corn which has its it becomes a zygote, then develops main flower at the top (called tassel), into the seed at a proper time and the corn fruit itself with its silks is  Double fertilization is the process the female flower which also contains unique to angiosperms in which one the ovary. sperm fertilizes the egg (forming a  In papaya, some varieties can have zygote) and the other sperm fertilizes both male and female flowers but BIO 277B. 39  Botany the polar nuclei (forming the primary endosperm nucleus). SEED  A seed (in some plants, referred to as a kernel) is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food.  The seed, which is an embryo with two points of growth (one of which  The picture above shows the forms the stems the other the roots) is structure of the seed as it is dissected enclosed in a seed coat with some food reserves.  The seed has 3 basic parts:  It is the product of the ripened ovule (1) Embryo of gymnosperm and angiosperm (2) Supply of Nutrients (for the plants which occurs after fertilization embryo) and some growth within the mother (3) Seedcoat plant. EMBRYO  Seed is a mature ovule that is  The embryo is an immature plant developed from the fertilization of the from which a new plant will grow under sperm and egg cell proper conditions.  The formation of the seed completes  Formed from the zygote the process of reproduction in seed  The embryo is further composed plants (started with the development into several embryonic parts: of flowers and pollination), with the (1) Cotyledon embryo developed from the zygote (2) Radicle and the seed coat from the (3) Plumule integuments of the ovule. (4) Epicotyl  Seeds have been an important (5) Hypocotyl development in the reproduction and (6) Embryonic sheath spread of flowering plants, relative to COTYELEDON more primitive plants like mosses,  The embryo has one cotyledon or ferns and liverworts, which do not have seed leaf in monocotyledons, two seeds and use other means to cotyledons in almost all dicotyledons propagate themselves. and two or more in gymnosperms. THREE BASIC SEED PARTS  The seed in the picture is therefore a dicotyledon as it has two cotyledons. RADICLE  The radicle is the embryonic root, which disappear once the plant matures in monocots while it grows the taproot in dicots. PLUMULE BIO 277B. 40  Botany  The plumule is the embryonic shoot.  The cotyledon shrinks once the  This contains both the cotyledon plants grows because they make use of (embryonic leaves) and the embryonic the starch in the cotyledon. This stems of the plant (epicotyl & happens until the plant is able to hypocotyl) produce large enough leaves to EPICOTYL undergo photosynthesis  The embryonic stem above the point  Cotyledons and endosperms have of attachment of the cotyledon(s) is the the same use in a plant. epicotyl.  Seeds can be classified according to  “ Epi-” means above. Thus, the name the amount of endosperms that they itself says “ above the cotyledon” have: HYPOCOTYL (1) Albuminous  The embryonic stem below the point (2) Exalbuminous of attachment is the hypocotyl. ALBUMINOUS  “ Hypo-“ means below so it signifies  Depend greatly on the endosperm that this stem is below the cotyledon. for nutrients so they are typically in larger amounts. SOURCE OF NUTRIENTS  Seeds with an endosperm at  The ENDOSPERM is the reserve maturity are termed albuminous seeds storage food of the seed until such time  Ex: monocots like grasses and palms that there is no variable temperature and many dicots like. brazil nut and and moisture for the seed to germinate castor bean it will use the endo sperm to germinate EXALBUMIOUS  Endosperm is triploid because  Seeds that have less or no fertilized by a sperm and two polar endosperm at maturity; more bodies making it triploid since all are cotyledon haploids  Ex: bean, pea, oak, walnut, squash,  Seeds also have limitations because sunflower, and radish without variable temperature and SEED COAT moisture, they will not be able to  The seed coat plays a very germinate and will die important role that protects the  In Ilonggo terms, it is called “ laon embryo for it to be able to germinate nga binhi” because the embryo is dead later on; some seed coats are even already causing the probability of resistant to fire like those of grasses germination to be very small  The seed coat helps protect the  COTYLEDON also serves as a embryo from mechanical injury and source of food of the plant as it from drying out. germinates (no photosynthesis  The seed coat is from a tissue happens yet) derived from the maternal tissue of the  Plants with small endosperms rely ovule. on cotyledon. BIO 277B. 41  Botany SPECIALIZED SEED PARTS HILUM  In addition to the three basic seed parts there are additional parts which include: (1) Aril (2) Hairs (3) Hilum (4) Funiculum ARIL  There may also be a scar on the seed coat, called the HILUM  This scar was previously where the  Some seeds have an appendage on seed was attached to the ovary wall by the seed coat such an ARIL (as in yew the FUNICULUS. and nutmeg)  Aril is the fleshy part that may sometimes be edible like in lychees and kamachile.  The funiculus