Plant Morphology: Roots, Stems and Leaves

• Spermatophytes are seed bearing plants

Angiosperms

• These are flowering plants.
• Angiosperms dominate seed bearing plants
• Differs from other seed plants because seeds are enclosed in an ovary.
• Vessel are present in the wood (xylem)
• Possess a complex reproductive structure - the flower
• The wood is a matured xylem

Gymnosperms

• They produce flower-like structures called cones
• Seeds are naked, and not enclosed in an ovary
• The wood (xylem) characteristically lacks vessels

Angiosperm Classes

• Divided into two classes of monocotyledons(monocots) and dicotyledons (dicots).

Dicots

• Possess two cotyledons.
• Have leaf veins usually with a net-like appearance.
• Have vascular bundles arranged in a ring.
• A taproot is usually present.
• Floral parts usually exist in multiples of 4–5.
• Most angiosperms are dicots

Monocots

• Have on cotyledon
• Veins are usually parallel.
• Vascular bundles complexly arranged.
• Consist of a fibrous root system.
• Floral parts exist in multiples of 3
• Examples include grasses, palms and orchids.
• Cotyledons refers to seed leaf
• Vein is the continuation of the vascular bundles.
• Bamboo is the tallest grass.

Plant Organ Systems

• Each plant has an integrated group of organ systems.
• Root System: It comprises the whole of the root of a plant
• Shoot system: Made up of two main organs:
  • The stem
  • the leaves
  • The flowers

Primary Functions of Organs

• Roots: Anchor the plant to the ground and absorbs water and minerals
• Conducts water and mineral ions to the shoot system
• Leaves: Site of photosynthesis
• Stems: Supports the leaves to carry out photosynthesis (PHS)
• Conducts water and mineral ions to the leaves and transport products of PHS from the leaves.
• Any other function other than these is a modification.
• The embryo is the early stage of a developing plant.

Dicot Embryo Seed Structure

• Consists of an axis with a radicle at one end and the plumule at the other end with two cotyledons (seed leaves).

Monocot Embryo Seed Structure

• Is essentially similar except that there is only one cotyledon.
• The cotyledon is usually shaped like a shield & termed "scutellum".
• Other differences include the presence of a coleoptile
• Protective covering of the Plumule and protective covering of the radicle.

Types of Seed Germination

• On germination the radicle grows into the primary root, the plumule produces the main part of the shoot system.
• There are two types of seed germination:
• Hypogeal germination and Epigeal germination
• The first sign of germination is the emergence of the radicle.

The Root System

• On germination, the radicle grows out of the embryo and develops into the first root or primary root.
• In most dicots the primary root becomes the principal root of the plant, w/ many branches (lateral roots) and forms a tap root system.
• Root cap and has root hairs a short way behind the tip.
• The root cap protects the root tip.
• Branch roots, whether arising from root or stem, are endogenous in origin - arise from within the tissues.
• They originate from The Pericycle.

Monocots Root System

• The primary root dies off and does not become the primary root.
• The fibrous roots arise from the base of the stem.

Shoot System

• Has no root cap; the apex is protected by young leaves.
• Consist of stems bearing leaves at points know as nodes.
• In the axil of each leaf is always at least one axillary bud.
• The stem between the nodes in called an internode.
• The leaf has a leaf blade/lamina, a leaf stalk/petiole and a swollen base.

Leaf Structure

• Leaves may be borne on a stalk or petiole
• When no petiole, and the leaf blade or lamina is directly attached to the stem, the leaf is sessile.
• When there is a petiole it is said to be petiolate or stalked.
• Base of the petiole may be swollen to form a structure called pulvinus (plural, pulvini).
• Commonly the petiole is cylindrical, but in many cases they are modified.
• At the base of the leaf may be present a pair of appendages called stipules.
• Stipules protects the premodial leaf (young leaf).
• Stipules are the lateral appendages of the leaf borne at its base and sometimes function to protect the shoot apex at a very early stage and young leaves in the bud.
• When green they manufacture food in the same way as leaves.
• Stipules are present in many families of dicots, but are absent or very rare in monocots.
• Some plants (many monocots) have sheathing leaf bases.
• When stipules are present the leaf is said to be stipulate.
• Often stipules aren't produced and such leaves are described as exstipulate.
• Stipules are part of leaf and not of the stem.

Types of Stipules

• Free lateral: Two free stipules usually small and green borne on the two sides of the leaf base
• Scaly stipules: small dry scales usually two borne on the two sides of the leaf base
• Adnate stipules: Two lateral stipules that grow along the petiole up to a certain height, adhering to it making it wing like in appearance.
• Interpetiolar stipules: stipulated borne between the petioles of opposite leaves called interpetiolar stipules
• Intrapetiolar stipules: stipules of a leaf fuse by their inner margins in such a way that this fusion product is axillary in position, situated between the stem and the petioles
• Ochreate stipules - forms a hollow tube encircling the stem from the node up to a certain height of the internode in front of the petiole
• Cauline stipules – borne on the stem free from the leaf itself, they appear to be independent organs.
• Foliaceous stipules - Two large green, leafy structure
• Bud scales stipules - scaly stipules which enclose and protect the vegetative bud.
• Spinous stipules - stipules modified into hard and pointed structures called spines. Such stipules prevent the plants from being eaten by animals

The Tap Root System

• In many dicot plants the radicle develops into a primary root or tap root.
• Many smaller branch roots may grow from the tap root.
• Taproots are normally thick, tapered roots (growing vertically downward).
• Branch roots are normally thinner and in many cases spread horizontally outwards.

The Adventitious Root System

• In monocot plants, the radicle is short lived and is replaced by numerous roots of more or less equal size.
• Root which arise after the formation of the original root system of a plant are termed adventitious roots.
• They grow from the base of the plumule. When they are established the radicle withers away.
• Adventitious roots develops from a stem, leaf or other plant parts. They may develop in both dicots and monocots.

Adventitious Root Types

• Fibrous Roots: found mainly in monocots. They are fibre-like and about the same length and thickness. They appear in clusters from base of stem. grasses and among farm crops e.g. maize, millet. Bamboo is a giant grass.
• Foliar roots: grow directly out of the leaf, mainly from the petiole or the vein. Such roots may arise spontaneously as a result of injury, or induced by hormones.

The Stem - Types:

• The stem cannot be easily classified, and It is difficult to make clear distinctions between the various types or kinds
• A small plant may have stems which are soft and green at the top and hard and woody at the base.
• The difference between a green herbaceous stem and a woody stem is in the degree of development rather than structure.
• Stems are mainly described as herbaceous or woody.
• The growth habit or form of the plant is determine by:
  • the nature of the stem,
  • the height the plant attain,
  • the duration/length of life cycle
  • Such forms can be described mainly as, herbs, shrubs and trees.
• Herbaceous plants have soft, green and flexible stems and are plants maybe classified as:

Stem (Life Forms)

• Annuals; complete their life cycle, i.e from seed germination to seed production and subsequently die in single season
• Biennials; require two seasons for a life cycle, attain vegetation 1st year, produce flowers in year 2
• Perennials persist for a number of years. They are long lasting

Stem (Other Forms)

• Shrubs: multi-stemmed woody plants that are usually less than 4 to 5 metres in height. Typically branches from roots.
• Trees: are perennial, woody plant with a single stem (trunk), normally greater than 4 to 5 metres. Heights goes up to 90 metres.
• Deciduous trees shed their foliage at the end of the growing season.
• Climbers: Plants have thin long stems, with diffuse branching, climb by means of special organs of attachment or by their twining stem
• Lianas; are very thick and woody perennial climbers found in forests which twine around tall trees to reach sunlight

Stems (Special Plant Types)

• Epiphytes; Plant that grows above the ground- but does not depend on it for nutrition,.
• Parasites; grow upon other living plants and absorbs food from the hosts by sucking roots called haustoria.
• Saprophytes; grow in places rich in decaying organic substances of vegetable or animal origin, and derive their nutrients from them
• Plants can also be classified depending on the habitat in which they are found:
  • Plants where water is sufficient: mesophytes
  • Plants found in desert habitat: xerophytes
  • Aquatic: hydrophytes.
  • Plants in salt marshes: halophytes

The Leaf - Types:

• Dicot leaf has venation while monocot leaf venation.
• Leaves may be simple when it has a single blade or compound the blade is completely divided into leaflets.
• Compound leaf has a bud in its axil, the leaflet has no axillary bud.
• Attached either to end of the petiole to sides of rachis.

Compound Leaves

• Pinnate compound leaves has leaflets which arranged on an elgonated. Leaflets can be arranged alternately or oppositely.
• Palmate compound leaves = Petiole produces multiple of leaflets.

Types of Pinnately Compound Leaves

• Unipinnate: Leaflets directly attached to a midrib.

Pinnately Compound Leaves May Be of the Following

• When the leaflets are in even number - paripinnate When the leaflets are in odd number - imparipinnate
• Bipinnate: compound leaf twice pennate (divided leaflets)

Leaf Arrangement

• Phyllotaxy is arrangement of leaves on a stem or branch Leaves alternate: When that is on leaf at level stem leaf spiralling
• Leaved Opposite: Leaves are side to be opposite when they are on the same node.
• Leaves are whorled: When three or more are attached at each node.
• Leaves are in Rosette: When a cluster appear at the base of stem

Leaf Types

• Tip
• Margin. Has 3 tips- Acute, Obture, Mucronate.
• The texture of the leaf may be covered to hair and gland.

Modifications of Plants

• Some plants have modifications that adapt for to the environment.

Roots:

• Storage of food in tuber
• water storage
• Breathing roots
• Aerial
• Contractile
• Parasitic to other source of food
• propgation

Stem

• Rhizomes
• Runners and Stolon
• Tubes
• Bulbs, Conrs and Cladophillys
• Tendrils used for attachment
• Thorns to avoid grazing -Succulent stems for water source

Leaves

• Tendrils used for attachment
• Spimes used for protection
• Floral is to attract pollunators
• Storage
• Succulent
• Insectivore

Modified roots

• Food storage.Roots become flesy storage from starch and cabrohydrates. Example carrot, cassavo, and sweet potatoes.
• Water Storage: Some grow in arid locations or lack rain. example; pumpkim
• Some plants like mangroves in marshy areas develop brething roots called pneumatophore in no air condionns

Arial Roots

• Form on from above a root
• Prop: roots produce from the mian root and branch downward penetrating example. corn, mangroce.
• Velamen or hanging is special absorbed in plants
• Photo- Synthetic. develop with chloro phhy

Modified Stem -Modified

• Roots special adaption of climbing from nodes or inernoden
• Butterfly- found in a large tropical forest producing huge amounts of trunk for stabilith

Rhizomes

• Underground stem bearing a terminal bud (ginger)
• The food from manufacturing is transported to sucrose.
• stems: swollen tops with underground
• Bulbs disc shaped leaves/inner stem
• Cores- swollrn vases of undergound stems.
• Clads- flatten green stem

Runners

• Stems by lateral branches green and lead scane. -

Storon; Stem by alternal and undergounod, runners call strom

offset

a shock runnee for branch, ivalt

• Succee, ltaeral branch near ground level.

Thornes

• Modification of stem for protection from axil with or without flowers
• Stem tendrl tendrls are thin, wiery

Succlecrnt stem

• plant stem stores water for water is to added from soil and cnditions where stem are groen reduced
• the petole often for holding for posrition as a example froms morning glory

Types of Special leaves

• Whole Leaf
• Stipude
• Leaftet
• Brach Leaves
• Spimes
• Flora leaves
• Scale leaves
• Insectuarious

Floral Morphology

• The flowers of most significant features. Highly modified specialized and compact
• Floral- All plant have base features regardless from
• Flower- develop and the stalk is called a pedinule and
• if ends the group on each is each stem is called a pechule -Carroed and the axial bract

Part of FLowers

• Sepal
• Petaks is next to the corallas.
• The sapal combined eith petaks for the penanth
• Stament male of thr plant

Componem

Stigentals - Stignetals - Stigentals

• • It if with one of
• A is the
• An with that or male or ferwlk but not botg
• A feritizer to fertilzation
• A that contains, the stement ferutze

Special types of The Plant Said.

The that are monoecions when made and female are four in the same plant.

• Ditoecous for the two seperate platns.
• that plants one.

Flower arrangement

• Moncoate number of parts that divisable for 3 .

• 4/5 multiples is the on stem and mode for flowering

• solitary and compend are main.

is defuute: These are determantr. Compsund are roups of racemic.

FLowers Types

• Recma are open in a low upward- -Sprek - open from the stem
• Spartdix - the spat contains many.
• Coyne flower opens for center. -

Monocot has only one catyleton Flower has multiple of 3 leaf vein paralled stems

• Dicoly has embrao with 2 cathlertons
• Pollen has multyolels
• majorleals are venited has

The roots that form is redicule

Explore plant morphology including root types (fibrous, foliar), leaf structures (bipinnate, quadrifoliate, pinnate trifoliate), stem types, and plant life cycles (annuals). Discover how plants adapt and grow based on these characteristics. Understand how they relate to the broader botanical world.