Plant Morphology Lecture 5 PDF

8/13/2024 ‫علم الشكل الظاهرى للنبات‬ Lecture ‫أستاذ مساعد تصنيف النباتات الزهرية والفلوره‬ http://www.youtube.com/@easybotany4u-M_OWIS 1 Underground Stem Modifications 2...

8/13/2024 ‫علم الشكل الظاهرى للنبات‬ Lecture ‫أستاذ مساعد تصنيف النباتات الزهرية والفلوره‬ http://www.youtube.com/@easybotany4u-M_OWIS 1 Underground Stem Modifications 2 1  8/13/2024 A. Underground Stems: Stems present completely beneath the soil.  Characters of underground stems:- perennial stems modified for the purpose of perennation and food storage. During unfavorable period the aerial plant dies but these stem survives. Under favorable period they give out aerial shoots. They differ from roots in: a) Presence of nodes and internodes. b) Presence of scale leaves and adventitious roots. c) Presence of axillary and terminal buds. d) They act as organs of vegetative propagation e) They are protected from herbivores by present in the soil. f) They show perennation and food materials and become fleshy and bulky. 3 4 2  8/13/2024  Based on the growth patterns, and the parts which store food material, underground stem modifications are of four types: 1. Rhizome  It is a stout, underground stem grows horizontally below the soil.  It is dorsiventrally differentiated and contain nodes and internodes, with scaly leaves at nodes, and has axillary as well as terminal buds.  It produce adventitious roots from the ventral side and produces aerial branches as well as reproductive organs from the dorsal side. The terminal buds in favorable conditions give rise to aerial branches. The axillary buds developed into branches which store food material as well as maintain horizontal growth of the rhizome. Examples: Canna, Cynodon. 5 Canna Cynodon. 6 3  8/13/2024 7 2. Corm  A short-enlarged underground, storage stem grows vertically in the soil.  It is swollen in appearance and bears nodes and internodes, with scale leaves at the nodes.  Axillary buds are present and develop into a daughter corm.  Apical bud is big and produces aerial shoot, which synthesizes food that is stored in corm, so the corm become tuberous.  Adventitious roots are developed from the base and sides. Some special adventitious roots (Contractile roots) are present and they fix into the ground so that the stem will grow downward.  Example: Colocasia ‫القلقاس‬ 8 4  8/13/2024 9 10 5  8/13/2024 11 3. Stem tuber  Swollen ends of underground branches of the plant body which store food and become tuberous.  It has distinct notches called eyes which represent the nodes.  Axillary buds are present in the eyes and give rise to new shoots.  Eyes are protected by scale leaves.  The eyes help in vegetative propagation.  They do not posses' adventitious roots. Example: Potato (Solanum tuberosum). 12 6  8/13/2024 13 14 7  8/13/2024 15 16 8  8/13/2024 4. Bulb  It is highly reduced and discoid underground stem with compressed nodes and internodes, bearing a large number of thickened overlapping fleshy storage leaves surrounded by scales.  In the centre lie terminal buds which give rise to aerial flowering shoots.  The scale leaves may bear axillary buds which in course of time produce daughter bulbs.  E.g.: Onion, garlic.  The base of the bulb consists of a cluster of adventitious roots. 17 18 9  8/13/2024 19 20 10  8/13/2024 21 In garlic (Allium sativum)  Axillary buds become fleshy and rounded due to food storage and known as “Bulbils”.  They detached from the plant, fall on the soil and develop into a new plant.  A sheath of dry membranous scale leaves covers the bulb. 22 11  8/13/2024 23 24 12  8/13/2024 Leaf  The leaf is a lateral, generally flattened outgrowth (appendage) born on the stem and develop from the nodes.  They are closely crowded together but separated and expanded when internodes elongate.  They are of a limited growth. 25 Leaf  Leaf Function: 1. Their main function is photosynthesis; they take in carbon dioxide from the atmosphere and give off oxygen. 2. Leaves also carry-on transpiration; as they giving off a water vapor. 3. Some leaves are also specialized for many other functions. 26 13  8/13/2024 Parts of the leaf Most leaves are differentiated into three parts (Base, Petiole and Blade). 27 28 14  8/13/2024 29 1- Leaf base  Leaf base: The base is the lower part of the leaf, neat its attachment with stem.  It may me swollen or not.  Sometimes it stores food and become fleshy 30 15  8/13/2024 Stipules  Stipule is a basal lateral appendages of a typical leaf of a flowering plant  Usually appearing paired on either side (sometimes just one side) of the leaf base.  They protect the axillary buds in developing stages.  They are prominent in dicots and rarely found in monocots.  Sometimes they absent or highly modified. 31 32 16  8/13/2024 Stipules ‫اﻻذينات‬  There are two types of leaves according to their stipules 1) Exstipulate leaf: have no stipules. 2) Stipulate leaf: with one or more Stipules. 33 Types of Stipules 1) Adnate stipule: If it's fused together on part of the petiole length, but the anterior is still free (e.g., Rosa). 34 17  8/13/2024 Types of Stipules 2) Foliaceous stipules: Are large leaf-like stipules which are generally used to photosynthesize food material (e.g., Pisum, Lathyrus). 35 3) Hairy stipules: These are hair-like or filamentous (e.g., Corchorus). 36 18  8/13/2024 Types of Stipules 4) Spinous stipules: Stipules are modified into hard and pointed spines which prevent the plants from being eaten by animals (e.g., Mimosa) 37 38 19  8/13/2024 Types of Stipules 5) Tendrillar stipules: Stipules are modified into tendrils which help plants in climbing (e.g., Smilax). 39 2- Petiole  The petiole is stalk-like part of the leaf which attach the blade to stem and places it in a favourable position with respect to light.  There are three types of leaves according to the presence of petiole:- 1. Petiolate leaf: with a petiole present. 2. Sessile leaf: without petiole, blade attached directly to the stem. 40 20  8/13/2024 2- Petiole 3. Subsessile leaf: with a very little petiole. E.g., Nerium 41 42 21  8/13/2024 43 3-Blade (lamina) ‫نصل الورقة‬ Is a broad, green part of the leaf, responsible for photosynthesis. 44 22  8/13/2024 45 46 23  8/13/2024  The veins form an easily ‫يمثل النوع الشائع في ذوات الفلقتين‬ recognizable network and found principally among the dicotyledons. ‫شبكي راحي‬ ‫شبكي ريشي‬  Larger veins giving rise to smaller and smaller branches in the green tissue (blade).  There are two types:  Pinnate and palmate (Duranta, Vitis). 47 The veins run parallel to one another. Veins are approximately of the same size and do not form a network. They occur among the monocotyledons. There are two types of parallel venation - a. Longitudinal venation:- Veins run generally from the base through the blade to the apex (wheat, Zea mays). b. Transverse venation:- Veins run transversally from a central midrib to the blade margin (banna) 48 24  8/13/2024  Based on the nature of the leaf blade, leaves are divided into:- Lamina (leaf blade) is entire and not split up Simple leaf into distinct leaflets as in Mango. Lamina (leaf blade) is not split up into distinct leaflets, but it is lobed as in lobed leaf Cotton. Lamina (leaf blade) is split into a number of Compound separate parts called leaflets as in Termis. leaf 49 50 25  8/13/2024 Shapes of simple leaves 1) Acicular:- needle shaped (Pinus). 2) Tubular:- Hollow tube (Allium cepa). 3) Linear:- Elongate shape (grasses). 51 Shapes of simple leaves 4) Lanceolate:- Long, wider in the middle, gradually tapering towards base and apex (Salix). 5) Ovate:- An egg-shaped blade, broader at the base than the top or/ oval shaped (Ficus bengalensis). 6) Cordate:- Heart-shaped with the petiole attached at the notch (Abutilon). 52 26  8/13/2024 Shapes of simple leaves 7) Reinform:- leaf blade is shaped like a kidney. 53 54 27  8/13/2024 55 A) pinnately lobed: Having lobes pinnately arranged on the central axis. 1) Pinnatifid: Having lobes with incisions that extend less than half-way toward the midrib. 2) Pinnatipartite: Having lobes with incisions that extend more than half-way toward the midrib. 3) Pinnatisec:: Having lobes with incisions that extend almost, or up to midrib. 56 28  8/13/2024 B) Palmately lobed: Lobes radiate from a single point. 1) Palmatifid: Palm-shaped, having lobes with incisions that extend less than half-way toward the petiole (blade base). 2) Palmatipartite: Having lobes with incisions that extend over half-way toward the petiole. 3) Palmatisect: Having lobes with incisions that extend almost up, but not quite to the petiole. 57 58 29  8/13/2024 59 60 30  8/13/2024 61 62 31  8/13/2024 63 64 32  8/13/2024 ‫اﻷوراق المركبة‬ ‫تنتظم الوريقات علي‬ ‫جانبي العرق‬ ‫الوسطي في ترتيب‬ ‫الراحية‬ ‫الريشية‬ ‫ريشي وتكون‬ ‫الوريقات متقابلة أو‬ ‫متبادلة على العرق‬ ‫الوسطي‬ ‫زوجية‬ ‫متضاعفة‬ ‫تخرج الوريقات جميعها‬ ‫فردية الطرف‬ ‫الطرف‬ ‫من نقطة واحدة في‬ ‫ وقد تكون‬،‫نهاية العنق‬ ‫الوريقات معنقة أو‬ ‫تنتهي بورقة‬ ‫نصل الوريقات‬ ‫تنتهي بورقتين‬ ‫جالسة كما فى الترمس‬ ‫واحدة في طرف‬ ‫مجزأ الي عدد من‬ ‫متقابلتين‬ ‫محورها‬ ‫الوريقات الثانوية‬ 65 1- Pinnately compound leaf:  Having two rows of leaflets on opposite sides of a central axis.  In this type of leaf, the mid rib is known as rachis. Leaflets are arranged on both sides of rachis.  Each leaflet is known as a pinna.  It is of following types:- a) Imparipinnate (odd pinnate): When the pinnate leaf terminates with a single leaflet. b) Paripinnate (even pinnate): Is a pinnately leaf with pair terminal leaflets c) Bipinnate: If the leaflets are themselves divided, the secondary divisions are known as pinnules and the leaf is known as bipinnate leaf. 66 33  8/13/2024 67 68 34  8/13/2024 2- Palmately compound:  In this type incision of leaf are directed from leaf margin to apex of petiole  Consisting of leaflets all radiating from one point. 69 70 35  8/13/2024 71 ‫الساق‬ ‫انواع ترت ب اﻷوراق ع‬ 1) Alternate: ‫أوراق مت ادلة‬ Single leaf arising at each node. eg. Eucalyptus 72 36  8/13/2024 2) Opposite: ‫أوراق متقا لة‬ Leaves occurring in pairs at the node, they may be:- A) Superposed ‫ متقا ل متوازي‬: Successive pairs of leaves stand directly over a pair in the same plane eg. Psidium (guava) B) Decussate ‫متقا ل متعامد‬: Leaves stands at the right angle to next upper or lower pair eg. Calotropis, Mentha 73 3) Whorled ‫أوراق مح ط ة أو سوار ة‬ Whorled – More than two leaves at each node eg. Nerium 74 37  8/13/2024 75 76 38  8/13/2024 Entire leaf margin 77 Serrate margin Leaf margins where the teeth are like those of a saw, continuous and forward pointing 78 39  8/13/2024 Dentate margin Have continuous teeth which point outwards 79 Crenate margin 80 40  8/13/2024 ‫حافة شوكية‬ 81 The picture can't be display ed. 82 41  8/13/2024 Quercus ‫البلوط‬ 83 84 42  8/13/2024 1) Acute: Sharp; usually referring to the apex of a leaf in which the two sides are straight and, when they meet, form an angle that is always less than 90°. 85 3) Acuminate: Gradually tapering to an acute apex with the sides being concave. 4) Caudate: attenuate with a slender tail-like appendage at the tip. 86 43  8/13/2024 5) Obtuse: blunt with margins form an angle form an angle greater than 90°. 6) Emarginate: Markedly notched, with a shallow depression at the apex. 87 88 44  8/13/2024 1) Leaf scale: These are undeveloped leaves that arise at the stem nodes. Leaves become thin, dry and form a membrane or paper like structure and serve to protect axillary buds as. 2) Leaf tendril: Leaf tendrils are found in a great number of climbing plants, the modification to tendril for climbing involves either the whole leaf or only part of it. 3) Leaf Spines: Leaves or any part of leaflet are modified into pointed spine. In Acacia and Euophorbia the stipules are modified into spines. 89 Spiny leaves 90 45  8/13/2024 4) Fleshy (Storage) Leaves: in onion, the leaf bases store food and become fleshy. In succulent plants, water storage in leave may occur as in the desert plant Zygophyllum coccineum. It has compound stipulates leaves each composed of petiole carrying two leaflets forming Y shaped structure. 91 5) Insectivorous Plants: In these plants, the leaves develop into some kind of traps with certain peculiarities to adapt them for trapping and digesting insects as in Nepenthes, Drosera, and Dionea. 92 46  8/13/2024 (i) Leaf pitcher – Leaves of some plants are modified to pitcher shape. eg. Nepenthes 93 (iii) Sticky leaf of Drosera (sundew) Sundews produce carnivorous leaves covered in tasty smelling, but very sticky mucilage nectar glands. When an insect, such as an ant, wanders across these leaves they get instantly stuck. Sensitive tentacles topped with red mucilage-secreting glands roll up around the struggling insect and the plant begins secreting digestive enzymes. 94 47  8/13/2024 (iv) Dionaea leaves The leaves of the Venus flytrap snap shut and trap prey within milliseconds by turning physical signals into electrical signals. Carnivorous plants, such as the Venus flytrap (Dionaea), rely on nutrients from small prey animals when growing in nutrient-poor soil 95 ‫اﻷسماء العلمية المقررة على الطﻼب‬  Allium cepa ‫( البصل‬Onion)  Allium sativum ‫( الثوم‬Garlic)  Zea mays ‫( الذرة‬Maize)  Cynodon dactylon ‫( النجيل‬Nageel)  Vicia faba ‫( الفول‬Broad bean)  Ricinus communis‫( الخروع‬Castor bean)  Acacia ‫( السنط‬acacias) 96 48  8/13/2024 Plant Morphology MCQs 1. Water is absorbed by 5. Sweet potato is a modification of 1.Root cap 1.Leaf 2.Root apex 2.Primary root 3.Root hairs 3.Adventitious root 4.Root 4.Underground root 2. Roots that develop from plant parts 6. Phyllotaxy is other than the radicle are 1.Folding leaf in the bud 1. Epicaulous 2.Arrangement of leaves on the stem 2. Fibrous 3.Both (1) and (2) 3. Adventitious 4.None 4. Epiphyllous 7. ————– is the characteristic of 3. Pneumatophores occur in plants of monocot plants 1.Marshy soil 1.Stilt roots 2.Saline soil 2.Taproots 3.Water 3.Fibrous roots 4.Sandy soil 4.Annulated roots 4. Food present in bulbil occurs in 1.Root 2.Petiole 3.Leaf base 4.Stem 97 8. Which root modification does not store 11. Velamen takes part in food? 1.Exchange of gases 1.Stilt 2.Transpiration 2.Conical 3.Absorption of moisture from the air 3.Napiform 4.Absorption of water from the soil 4.Tuberous 12. Leaves are attached to the stem at 9. Bulbils participate in 1.Internode 1.Vegetative reproduction 2.Nodes 2.Sexual reproduction 3.Apical meristem 3.Respiration 4.Axillary meristem 4.Transpiration 13. The outer covering of the epiphytic 10. Nodulated roots enrich the plant with root is 1.Proteins 1.Rhizophore 2.Fats 2.Osmophore 3.Carbohydrates 3.Pneumatophore 4.Food 4.Velamen 98 49  8/13/2024 Frequently Asked Questions Q1 What do you mean by the morphology of leaves? Morphology is the study of science that deals with the form and structure of an organism. Q2 What are the different types of leaves? There are two different types of leaves – simple and compound leaves. Simple leaves are lobed or divided but do not form distinct leaflets. Whereas, in a compound leaf the leaves are divided into distinct leaflets and each leaflet has a small petiole. Q3 What are the different shapes of the leaves? There are various types of leaves, each with its own shapes. These shapes range from oval, elliptical and linear, to truncate and lanceolate. Q4 What is the different modification of leaves? Leaves can be modified in the form of spines that reduce water loss and also act as a defence. Some are modified into tendrils to provide support to the plant. Some leaves are thick that help in water storage. Some are modified to catch and digest insects. 99 With my best wishes….. ً‫فإن لكل يوم عمﻼ‬....‫ﻻ تؤجل عمل اليوم إلى الغـد‬ 100 50