Leaf & root by pooja

Leaf & root by pooja

• 1.
  LEAVES: FORM &FUNCTION • Defination • Function • External Anatomy • Internal Anatomy • Specialized Leaves
• 2.
  The Plant Body:Leaves • Defination: is green flatened outergrowth of the stem or branch developing from a node. • FUNCTION OF LEAVES – Photosynthesis – Gaseous exchange – Transpiration (excess water absorbed by root, evaporate that through lower surface of leaf) – Storage of food(flashy leaf : aloe) – Vegetative propogation (fern) – Protection(by stipules-Acacia) – Support(tendrils) – Polination (attracting insect by color)
• 3.
  Uses of leaves •As a source of food • As a source of fiber • As a fodder • As a dye • Ornamental purpose(house) • Purgative • Cardiotonic • expectorant • Fenugreek • Banana • Grasses • henna • Croton • Senna • Digitalis • Vasaka
• 4.
  EXTERNAL ANATOMY • Leavespossess 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. • Petiole: attaches leaf blade to stem • Petiolate(present) & sessile(absent)
• 5.
  Parts of leaves •Apex – Tip of leaf • Base – Attaches to petiole – if petiole is absent, attaches directly to stem • Margin – Edge of leaf • Epidermis – “Skin” of leaf - responsible for gas exchange • Stomata – Outside layer of leaf opening in epidermis where gas and water exchange • Mesophyll – Middle layer of leaf where photosynthesis occurs
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  EXTERNAL ANATOMY
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  Leaf types -Simple, compound, peltate and perfoliate • Simple leaf = undivided blade with a single auxiliary bud at the base of its petiole. • Compound leaf = blade divided into leaflets, leaflets lack an auxiliary bud but each compound leaf has a single bud at the base of its petiole – pinnately- Pinnately compound Leaves have the leaflets arranged along the main or mid-vein. Odd pinnate With a terminal leaflet; e.g., Fraxinus (ash).Even pinnate lacking a terminal leaflet; e.g., Swietenia (mahogany). – palmately-compound leaves: leaflets attached at the same point at the end of the petiole; like fingers of the palm of a hand. examples of plants with this leaf type include buckeye, horse chestnut, hemp or marijuana, and shamrock. • Perfoliate leaves = sessile leaves that surround and are pierced by stems; examples include yellow-wort and thoroughwort
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  • Bipinnately compoundLeaves are twice divided: the leaflets are arranged along a secondary vein that is one of several branching off the rachis. Each leaflet is called a "pinnule". The group of pinnules on each secondary vein forms a "pinna"; e.g., Albizia (silk tree). • Trifoliate (or trifoliolate)A pinnate leaf with just three leaflets; e.g., Trifolium (clover), Laburnum (laburnum) • Pinnatifid Pinnately dissected to the central vein, but with the leaflets not entirely separate; e.g., Polypodium, some Sorbus (whitebeams).
• 9.
  Leaf types –Pinnately & Palmately Compound Leaves
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  Peltate & PerfoliateLeaves Mayapple Yellow Wort Peltate leaves = petioles that are attached to the middle of the blade; e.g. include mayapple Perfoliate leaves = sessile leaves that surround and are pierced by stems; e.g. include yellow-wort and thoroughwort
• 15.
  Venation = arrangementof veins in a leaf • Netted-venation = one or a few prominent midveins from which smaller minor veins branch into a meshed network; common to dicots and some nonflowering plants. – Pinnately-veined leaves = main vein called midrib with secondary veins branching from it (e.g., elm). – Palmately-veined leaves = veins radiate out of base of blade (e.g., maple). • Parallel venation = characteristics of many monocots (e.g., grasses, cereal grains); veins are parallel to one another. • Dichotomous venation = no midrib or large veins; rather individual veins have a tendency to fork evenly from the base of the the blade to the opposite margin, creating a fan-shaped leaf (e.g., Gingko).
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  Venation Types Netted orReticulate Venation
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  Image Term Description ArcuateSecondary arching toward the apex Dichotomous Veins splitting in two Longitudinal All veins aligned mostly with the midvein Palmate Veins coming from one point like fingers come from the palm of the hand Parallel All veins parallel and not intersecting Pinnate Secondary veins borne from midrib Reticulate All veins branching repeatedly, net veined Rotate Veins coming from the center of the leaf and radiating toward the edges Transverse Nervure tertiaire reliant les nervures secondaires
• 18.
  phyllotoxy • Different termsare usually used to describe the arrangement of leaves on the stem (phyllotaxis): • The leaves on this plant are arranged in pairs opposite one another, with successive pairs at right angles to each other (decussate) along the stem. Note the developing buds in the axils of these leaves. • AlternateLeaf (Spiral) attachments are singular at nodes, and leaves alternate direction, to a greater or lesser degree, along the stem. BasalArising from the base of the stem. Cauline Arising from the aerial stem. • Opposite Two structures, one on each opposite side of the stem, typically leaves, branches, or flower parts. (Decussate & superposed) • Whorled, or verticillate Three or more leaves attach at each point or node on the stem. As with opposite leaves, successive whorls may or may not be decussate, rotated by half the angle between the leaves in the whorl (i.e., successive whorls of three rotated 60°, whorls of four rotated 45°, etc.). Opposite leaves may appear whorled near the tip of the stem.
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  Phyllotaxy - Arrangementof leaves on a stem
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  LEAF – InternalAnatomy
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  Structures of theLeaf Photosynthesis Conserves water Transports water and sugar to stem and roots
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  Internal and ExternalViews
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  Deciduous Leaves &Leaf Abscission
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  Specialized or ModifiedLeaves • Cotyledons: embryonic or "seed" leaves. First leaves produced by a germinating seed, often contain a store of food (obtained from the endosperm) to help the seedling become established. • Tendrils - blade of leaves or leaflets are reduced in size, allows plant to climbing to other objects (e.g., sweet pea and garden peas. ) • Shade leaves = thinner, fewer hairs, larger to compensate for less light; often found in plants living in shaded areas. • Drought-resistant leaves = thick, sunken stomata, often reduced in size – In American cacti and African euphorbs, leaves are often reduced such that they serve as spine to discourage herbivory and reduce water loss; stems serve as the primary organ of photosynthesis. – In pine trees, the leaves are adapted to living in a dry environment too. Water is locked up as ice during significant portions of the year and therefore not available to the plant; pine leaves possess sunken stomata, thick cuticles, needle-like leaves, and a hypodermis, which is an extra cells just underneath the epidermis -
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  • Prickles andthorns: epidermal outgrowths on stems and leaves (e.g., holly, rose, and raspberries; Hypodermic trichomes on stinging nettles. • Storage leaves succulent leaves retain water in large vacuoles. • Reproductive leaves, (e.g., Kalanchöe plantlets arise on margins of leaves. • Insect-trapping leaves: For example: pitcher plants, sundews venus flytraps, and bladderworts have modified leaves for capturing insects; All these plants live under nutrient-poor conditions and digest insect bodies to obtain nitrogen and other essential nutrients. • Bracts: petal-like leaves. • Window Leaves: plant is buried in soil with transparent part exposed to light. Being buried reduces loss of war in arid environments. • Flower pot leaves: Structure to catch water and debris for nutrient collection - fairy-elephant's feet.
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  Cotyledons or “seedleaves”
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  Tendrils Garden Pea
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  Leaves as Needlesand Spines
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  Leaves as ColorfulBracts
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  Monocot vs dicotleaves
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  • Monocot Leaf •Symmetry: Isobilateral • Stomata distribution: Amphistomatic i.e., stomata equally distributed on both the surfaces. • Bulliform cells: Present on upper epidermis. • Mesophyll: Only spongy parenchyma is present which has very small intercellular spaces. • Bundle sheath: Made of parenchyma but just above and below the vascular bundles are found sclerenchymatous cells (upto epidermis) • Dicot Leaf • Symmetry: Dorsiventral • Stomata distribution: Hypostomatic i.e., stomata present on lower surface of leaf. • Bulliform cells: Usually absent. • Mesophyll: Made up of two types of tissues: Palisade parenchyma and spongy parenchyma with large intercellular spaces. • Bundle sheath: Made up of parenchyma. Just above and below the vascular bundle some parenchymatous cells or collenchymatous cells are present up to epidermis.
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  MONOCOTS DICOTS Embryo withsingle cotyledon Embryo with two cotyledons Pollen with single furrow or pore Pollen with three furrows or pores Flower parts in multiples of three Flower parts in multiples of four or five Major leaf veins parallel Major leaf veins reticulated Stem vacular bundles scattered Stem vascular bundles in a ring Roots are adventitious Roots develop from radicle Secondary growth absent Secondary growth often present
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  R00T • Roots absorbwater, minerals, and nutrients from the soil, and they anchor the plant to the ground or other substrate. • They often lack coloration, but sometimes they may be highly colored (carrots for example). • They lack leaves, nodes, and internodes. • Roots are often found at the very bottom of the plant, below the soil level. However, they can also emerge from stem tissue - often at nodes (think of the ivy plants that you see around town - their roots anchor their climbing stems to the walls of fences or houses).
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  TYPES OF ROOTSYSTEMS G TAP ROOTS FIBROUS ROOTS ADVENTIOUS ROOTS •Prominent in dicot •Prominent in monocots •They develop from organs •Primary roots grow & becomes stout. •Roots develop from lower nodes Of shoot system •Secondary & tertiary grow from primary root •They have same length & diameter
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  Roots Taproot System Primary rootsgrow down from the stem with some secondary roots forming Image found at: http://www.arboretum.fullerton.edu
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  Roots Fibrous Root System Small lateral roots that spreadout just below the soil surface Image found at: www.wildmanstevebrill.com
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  Root Functions • Absorptionof water and nutrients – performed by root hairs • Transportation of water and nutrients to stem • Anchor plant to maintain stability • Store food and water Roots have 4 primary functions
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  Parts of theRoot • Epidermis – Outermost layer of cells, like the skin of the root • Cortex – Tissue inside epidermis that stores starch and other substances for the growth of the root
• 41.
  Parts of theRoot 1) Root Cap: covered over the apex by cap. • Absent in aquatic plant • Provides protection for the root tip 2) Region of cell division: • Growing apex of root, just beyond root cap 3) Region of elongation: • Lies above the meristmatic region & extend to a length of few mm. 4)Root Hairs • Site of absorption (water & mineral salt) 5)Vascular Tissue • Within cortex, contains cells that transport water, nutrients, and minerals to all parts of the plant
• 42.
  THE ROOT LOCATION- grows underground TYPESOF ROOTS- 1) Primary- formed directly from axis of embryo plant. 2) Lateral- arises from primary.
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  STORAGE ROOTS SWOLLEN TAProots • FUSIFORM-eg:raddish • NAPIFORM-eg:beetroot • CONICAL -eg;carrot SWOLLEN ADVENTIOUS ROOTS FASICULATED-eg asparagus NODULATED -eg: ginger MONILIFORM-eg: grasses Sweet potato
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  PROP ROOTS IN BANYAN TREE, Branches giveoff roots that grow into the soil & support the branches
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  STILT ROOTS IN SCREWPINEshort roots grow obliquely downward from near base of stem
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  CLIMBING ROOTS IN climberslike PEPPER & BETEL NUT, adventitious roots are formed at nodes which help in climbing.
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  EPIPHYTIC ROOTS IN VANDA,Base of tissue grows spongy tissue termed velamen that absorbs moisture from the air
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  CONTRACTILE ROOTS IN COLACASIA, Theyposses roots that contract so underground roots are kept at proper levels.
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  FLOATING ROOTS IN JUSSIAEA roots are white, spongy filledwith air. Help plants to float
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  BREATHING ROOTS IN AVICENNIA, Roots grow intovertical branches that have openings called Pneumetapho res for root aeration.
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  REORODUCTIVE ROOTS Exposed rootsof MURRAYA Have adventitious buds which grow into new plants.
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  PARASITIC ROOTS IN CUSCUTA,Haustoria Penetrate into host stem & enter vascular bundles which absorb materials.
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  ASSIMILATORY ROOTS IN TRAPA, Adventious roots with chlorophyllous tissuecapable of photosynthesis.
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  FOLIAR ROOTS IN BRYOPHYLLUM Roots arisefrom lamina, petiole,veins
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  TUBERCULAR ROOTS IN SWEETPOTATO, Lateral roots are swollen & Without definite shape.
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  Functions of the Stem•Transport water and nutrients from roots to leaves • Supports leaves, fruit, and flowers • Food storage Image found at: www.karencarr.com
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  Parts of the Stem •Node – Areas where side branches and leaves develop • Internode – Area between nodes • Xylem – Carries nutrients up • Phloem – Carries nutrients down • Pith – Stores food Image found at: www.ext.colostate.edu