LET’S part of the axis bearing branches, leaves, flowers

LET’S KNOW THE TERMS FIRSTAnatomy: The study of internal structure of plantsMorphology: The external structure of plants Cotyledon: Central portion of a seed embryo to which the epicotyl (immature shoot) and radicle (immature root) are attachedMonocotyledonous plants: Flowering plants (angiosperms) whose seeds typically contain only one embryonic leaf, or cotyledon Dicotyledonous plants: Angiosperms that have a pair of leaves, or cotyledons, in the embryo of the seedTissue: Collection of similar cells, with specific function.MORPHOLOGY OF PLANTSRoot System: The underground part of the plant that comprises rootsShoot System: The portion of the plant above the ground that comprises stem, leaves, fruits and flowersTHE ROOTUnderground part of the plant.Anchors the plant in the soil and absorbs water and minerals from the soil. Developed from Radicle of the embryo of a germinating seed.Types of roots:Tap root: originates from the radicle and is found in dicotyledonous plants, e.g. mustard, gram etc.Fibrous root: originates from the base of the stem and is found in monocotyledonous plants, e.g. wheatAdventitious roots: originates from parts  of the plant other than radicle, e.g. Banyan tree.Regions of the RootRoot cap: thimble-like structure covering the root apex; protects the tender apex of the root as it makes its way through the soil.Region of meristematic tissue: present a few millimeters above the root cap. Cells are very small, thin-walled and with dense protoplasm and divide repeatedly.Region of root elongation: cells of this region undergo rapid elongation and enlargement; responsible for the growth of the root in length.Region of maturation: cells of this zone gradually differentiate and mature. Root hairs formed from some of the epidermal cells; they are very fine and delicate, thread-like structures and absorb water and minerals from the soil.THE STEMAscending part of the axis bearing branches, leaves, flowers and fruits.Develops from the plumule of the embryo of a germinating seed.Bears nodes and internodes.     Bears buds, which may be terminal or axillary.Conducts water, minerals and photosynthates.Some stems perform the function of storage of food, support, protection and vegetative propagation.THE LEAFFlattened structure generally borne laterally on the stem.Develops at the node and bears axillary bud that develops into a branch later.Originate from shoot apical meristems Arranged in an acropetal (upwards from the base or point of attachment) order.Organs for photosynthesis.Parts of leafLeaf base: Attaches the leaf to the stem; may bear two lateral small leaf like structures called stipules.Petiole: Helps in holding the lamina towards light; Long thin flexible petioles allows the lamina to flutter in wind and helps in cooling the leaf Lamina: Also k/a leaf blade; green colored expanded part of the leaf with veins and veinlets; A prominent vein called midrib is present in the middle. Veins provide rigidity to the lamina and transport water and minerals.Venation: arrangement of veins and the veinlets on the lamina of leaf Reticulate venation: When the veinlets form a network. e.g., Dicots.Parallel venation: When the veins run parallel to each other within a lamina. e.g., Monocot.Reticulate and parallel venation   THE FLOWERReproductive unit of the plant and meant for sexual reproduction.Four different whorls are present that are arranged successively on the swollen end of the stalk or pedicel, called thalamus: calyx, corolla, androecium and gynoecium.Calyx and corolla: Accessory organsAndroecium and gynoecium : reproductive organs.  Parts of a FlowerCalyx (Sepals) Outermost whorl of the flower.Green leaf-like and protect the flower in bud stage.Sepals can be united (gamosepalous) or can be free (polysepalous).Corolla (Petals)Has varied shape and color in different plants.Brightly colored for attracting the insects for pollination.Corolla may be gamopetalous (free) or polypetalous (united).  Androecium (Stamens)Male reproductive partConsists of a stalk or a filament and an anther.Bilobed and each lobe has two chambers called pollen-sacs that produce pollen grainsGynoecium (Carpels/Pistils) –Female reproductive partConsists of 3 parts:Ovary:  enlarged basal partStyle: connects the ovary to the stigma.Stigma: tip of the style; receptive surface for pollen grains.Each ovary bears one or more ovules attached to a flattened, cushion-like placenta.Types of gynoecium:Monocarpellary:  when only one carpel is present.Multicarpellary: when more than one carpel is present.Apocarpous: when carpels are free. e.g., lotus Syncarpous: when carpels are fused. e.g., mustard After fertilization:  ovules develop into seeds; ovary matures into a fruit.AestivationArrangement of sepals or petals in floral bud with respect to the other members of the same whorl Valvate: When sepals or petals in a whorl just touch one another at the margin, without overlapping. Twisted:  When one margin of the appendage overlaps with that of the next one and so on. Imbricate: When the margins of sepals or petals overlap one another but not in any particular direction.Vaxillary: In this, there are five petals, the largest (standard) overlaps the two lateral petals (wings), which in turn overlap the two smallest anterior petals (keel).   THE FRUITCharacteristic feature of angiosperms, developed after fertilization from mature or ripened ovaryParthenocarpic fruit: formed without fertilization of the ovaryConsists of a wall or pericarp (can be dry and fleshy) and seeds.Thick and fleshy pericarp differentiates into the outer epicarp, the middle mesocarp and the inner endocarp.THE SEEDSeeds develop from ovules after fertilization. Consists of a seed coat and an embryo.Made up of a radicle, an embryonal axis and one or two cotyledons.ANATOMY OF PLANTSEvery plant consists of various tissues. They consist of either one or different types of cells. Meristematic TissuePerform mitosis and produce cellsConsists of small cells, thin-walled, no central vacuole and no specialized features.Located in the apical meristems at the growing points of roots and stems and the secondary meristems (lateral buds) at the nodes of stems (where branching occurs) Cells produced differentiate into one or another type.PeridermOutermost layer of stems and roots of woody plants Also called as barks.Replace epidermis in plants that undergo secondary growth..Include cork cellsProvides protection from injuries, pathogens and also from excessive water loss.EpidermisOutermost layer of the primary plant body covering roots, stems, leaves, floral parts, fruits and seeds.One layer thick with cuticle.Composed of unspecialized cells- parenchyma and sclerenchyma.ParenchymaGeneral cells of plantsCircular in shape with very thin wall.Present in all plant cells.Have very large vacuoles Found in all roots, stem, leaves and in fruitsParenchyma cells help in synthesizing and storage of synthesized food products.Controls plant’s metabolism like photosynthesis, respiration, protein synthesis.Help in wound healing and regeneration.CollenchymaSpecialized parenchyma tissue found in all green parts.Elongated cells with unevenly   thickened wallsControl the functions of young plants. Provides a support to plants by not restraining growth, which is caused due to their absence of secondary walls and hardening agent in their primary walls. SclerenchymaRigid, non-living cells.Have thick secondary walls and lack protoplasts at maturityProvide strength .XylemPresent in the veins.Dead cellsConsists of hollow cells having only cell wallTransport water and dissolved nutrients from the roots to all parts of a plant.Transport the nutrients from the root to the stem, leaves and flower.Also called as water-conducting tissue.PhloemLiving cells with no nucleus and organelles.Transport the nutrients from the leaves to the different parts of the plant.Also called as sugar-conducting tissue.