Morphology of Flowering Plants Quiz

Morphology of Flowering Plants

• Morphology is the study of the external forms of organisms.
• Angiosperms (flowering plants) are characterized by the presence of roots, stems, leaves, flowers, and fruits.

Main Parts of Flowering Plants

• Root System (Underground parts):

  • Primary root: The initial root formed from the radicle of the embryo.
  • Lateral roots: Branches from the primary root, including secondary and tertiary roots.
  • Root hairs: Fine, delicate structures on the roots that absorb water and minerals from the soil.
  • Root cap: The covering at the apex of the root that protects the tender root tip.
  • Region of meristematic activity: The region just behind the root cap with actively dividing cells.
  • Region of elongation: The region just above the meristematic region, where cells grow and elongate.
  • Region of maturation: The region behind the region of elongation where cells differentiate and mature.

• Shoot System (Above the ground parts):

  • Stem: The ascending part of the axis that develops from the plumule of the embryo. It bears branches, leaves, flowers, fruits, terminal or axillary buds and internodes.
  • Leaves: Lateral, flattened structures borne on the stem from nodes.
  • Axillary buds: Buds in the angle between the leaf and stem that can develop into branches.
  • Apical bud (terminal bud): Bud at the tip of the stem.

The Root

• It is the underground part of the plant that develops from the radicle of the embryo.
• Tap root system: These roots have a primary root that is prominent and extends deep into the soil.
  • Seen in dicotyledons (plants with two seed leaves, like mustard plant).
  • The primary root is the elongated portion that develops from radicle.
• Fibrous root system: These roots have numerous thin roots of roughly equal size that originate from the base of the stem.
  • Seen in monocotyledons (plants with one seed leaf, like wheat).
• Adventitious root system: Roots that develop from parts other than the radicle, such as stems or leaves.
  • Seen in grass, Monstera, and banyan tree.

Regions of the Root (in detail)

• Root cap: Protects the tender apex of the root.
• Region of meristematic activity: Cells very tiny, thin walled with dense protoplasm. Divide rapidly.
• Region of elongation: Cells grow rapidly. Helps in the growth of the root.
• Region of maturation: Cells differentiate and mature; specialized transport cells develop (includes root hairs).

Modifications of the Root

• Swollen roots for food storage: Tap roots (like carrot, turnips) and adventitious roots (like sweet potato) store food.
• Prop roots: Supporting structures, like those of the banyan tree.
• Stilt roots: Roots from the lower nodes of the stem (like maize and sugarcane).
• Pneumatophores: Roots that grow vertically upwards to obtain oxygen in swampy areas (e.g. Rhizophora).

Functions of the Root

• Absorption of water and minerals from the soil
• Provide proper anchorage to plant parts
• Storage of reserve food materials
• Synthesis of plant growth regulators

The Stem

• The ascending part of the axis, developing from plumule. Bears leaves, branches, flowers, fruits, and buds. Has nodes and internodes.

Functions of the Stem

• Spreading branches bearing leaves, flowers, and fruits
• Conducts water, minerals, and photosynthates
• Helps in food storage, support, protection and vegetative propagation

Modifications of the Stem

• Food storage (e.g., potato tubers, ginger rhizomes, turmeric rhizomes, Colocasia, zaminkand).
• Stem tendrils (e.g., cucumber, pumpkin, watermelon, grapevines) help the plant climb.
• Thorns (e.g., Citrus, Bougainvillea) for protection.
• Phylloclades (e.g., Opuntia, Euphorbia): Leaf-like stems for photosynthesis in arid regions.
• Stolons (e.g., mint, jasmine): A horizontal stem that grows along the ground, and creates new plants.
• Offsets (e.g., Pistia, Eichhornia): Short internodes; vegetative propagation
• Suckers: Lateral branches that arise from the basal underground portions that grow horizontally beneath the soil giving rise to leafy shoots (e.g. banana, pineapple, chrysanthemum).
• Underground stems in certain species aid in the spread of the species to new locations and perennation.

The Leaf

• A lateral, flattened structure borne on the stem. Forms at the nodes.
• Axillary bud develops into a branch.
• Leaves develop from shoot apical meristems and have an acropetal order
• Parts of Leaf:
  • Leaf base
  • Petiole
  • Lamina (blade)
• Venation: The arrangement of veins and veinlets in the leaf lamina.
  • Reticulate (network) venation: seen in dicots
  • Parallel (parallel lines) venation: seen in monocots
• Types of Leaf:
  • Simple leaf: A single leaf blade that isn't divided into leaflets.
  • Compound leaf: A leaf blade that is divided into leaflets.
    • Pinnately compound: Leaflets arranged on either side of a central axis, called the rachis. e.g. Neem
    • Palmately compound: Leaflets radiating from a common point at the end of the petiole (e.g., silk cotton tree).

Phyllotaxy

• The arrangement of leaves on the stem or branch.
• Alternate: One leaf per node, alternating around the stem.
• Opposite: Two leaves per node, directly across from each other.
• Whorled: Three or more leaves per node arranged in a circle/whorl.

Modification of Leaves

• Tendrils (climbing)
• Spines (protection)
• Fleshy leaves (food storage).

The Flower and Inflorescence

• A flower is a modified shoot wherein the shoot apical meristem changes to floral meristem.
• Internodes do not elongate. The axis gets condensed.
• The apex produces various floral appendages laterally at successive nodes instead of leaves.
• A shoot tip transforms to a flower; it's solitary.
• Inflorescence: Arrangement of clusters of flowers on the floral axis, based on whether the apex gets converted into a flower or continues to grow. Two types:
  • Racemose: The main axis continues to grow, and flowers develop laterally in an acropetal order.
  • Cymose: The main axis terminates with a flower and growth stops, so flowers develop in a basipetal order (youngest flower at the bottom).

Parts of a Flower

• Calyx: Outermost whorl made of sepals (typically green; protect bud).
• Corolla: Inner whorl made of petals (usually colored to attract pollinators).
  • Gamopetalous: Petals fused.
  • Polypetalous: Petals free.
• Androecium: Male reproductive part; consisting of stamens (filament & anther).
  • Epipetalous: Stamens attached to petals
  • Epiphyllous: Stamens attached to perianth.
  • Polyandrous: Stamens free
  • Synandrous: Stamens fused
    • Monadelphous: Stamens united into a single bundle.
    • Diadelphous: Stamens united into two bundles
    • Polyadelphous: Stamens united into many bundles
• Gynoecium: Female reproductive part; consisting of carpels/pistil (stigma, style, ovary).
  • Polycarpellary (many carpels)
    • Apocarpous: Carpels free
    • Syncarpous: Carpels fused together.
• Placentation: Arrangement of ovules within the ovary.
  • Marginal
  • Axile
  • Parietal
  • Free central
  • Basal

The Fruit

• A ripened ovary.
• Develops after fertilization.
• A characteristic feature of flowering plants.
  • Types of fruits:
    • Drupe: One seed develops from a monocarpellary superior ovary (e.g., mango, coconut).
    • Other types: Parthenocarpic fruit (without fertilization).
• Pericarp: Fruit wall (may be dry or fleshy) with layers:
  • Exocarp (outer layer)
  • Mesocarp (middle layer)
  • Endocarp (inner layer/around the seed)

The Seed

• Mature ovule following fertilization.
  • Seed Coat (outer testa and inner tegmen)
  • Embryo
    • Embryonal axis
    • Cotyledons (one in monocots, two in dicots)
    • Radicle (embryonic root)
    • Plumule (embryonic shoot)

Structure of Seed (dicot)

• The outermost covering of the seed is the seed coat.
• The seed coat has two layers: outer testa and inner tegmen.
• On the seed coat, there is a scar called the hilum.
• Above the hilum is a small pore called the micropyle.

Structure of Seed (monocot)

• The embryo is small and situated in a groove at one end of the endosperm. Embryo consists of one large cotyledon (scutellum); a short axis; plumule; radicle.
• The plumule is protected in a sheath called coleoptile and the radicle is protected in a sheath called coleorhiza.

Semi-Technical Description of a Typical Flowering Plant

• Describes plant: habit, vegetative characters, floral characters, floral diagram, and floral formula.
• Uses symbols (e.g., K, C, A, G, floral formula of mustard).

Test your knowledge on the morphology of flowering plants, focusing on their root and shoot systems. This quiz covers key structures such as roots, stems, leaves, flowers, and fruits, as well as the different regions of the root. Identify and understand the various parts vital for angiosperms.