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Subjects /Biology / Plant Morphology

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INTRODUCTION
20 Apr 2021

Morphology means the study of forms and features of different parts of plants like leaves, roots, flower etc.

In this article we will learn about

  • Roots
  • Stem
  • Flower
  • Fruits

Bryophyta

  • This group of plant lacks xylem and phloem.
  • They also lack roots, stem and leaves. Thus, water transportation takes place through parenchyma.

Petridophyta

  • This group of plants is found in wet places like forests and mountains.
  • Plants have stem, roots and leaves.
  • Examples: Ferns, Mosses

Phanerogamous Plant

  • Plants of this group are well developed.
  • They have roots, stem and leaves.
  • Xylem and phloem are also well developed.
  • It is further divided into two types:
    • Gymnosperm
      • Trees and bushes form this group.
      • Plants are woody, perennial and tall.
      • The plant has naked seeds.
    • Angiosperm
      • Roots, leaves, flowers and fruits are fully developed.
      • The seeds are found inside the fruits.
      • For example: Wheat, Lemon and potato etc.

Root System in Plants

  • The absorption of water occurs through roots by diffusion, osmosis and other processes.
  • The root develops from radicle.
  • Root Hair: Water is absorbed from the soil by the root hair. The hair system of the roots is unicellular outgrowth of roots.
  • The process by which these root hairs (hydrophilic substance) absorb water is called as imbibition.
  • It helps in absorbing nutrients, water and moisture from the soil. Click to read about transportation of water and nutrients in plants.

Two types of roots are:

1. Tap Root

  • The main root with minor side roots grow deep into the soil is called taproot.
  • It arises from the radicle of the plants.
  • It occurs in dicots plants.
  • For example: in Trees, shrubs and plants. Carrot, Reddish etc.

2. Adventitious Root

  • The fine, thick hair like structure of root that spread sideways in all the direction is called adventitious root.
  • It is also called fibrous root.
  • It grows from the stem and leaves and not from the radicle.
  • It occurs in monocots.
  • For example: in Grasses, Onion etc.

Flower

Flower is the reproductive part of the plant.

The following are the parts of flower:

  • Androecium
  • Gynoecium
  • Calyx
  • Corolla

Two types of reproduction take place through flowers:

  • Asexual Reproduction: Plant gives rise to new plant without seeds.
  • Sexual Reproduction: Seeds give rise to new plants.
    • Stamens are the male reproductive part of the plant.
    • Pistil is the female reproductive part of the plant.

There are two types of flowers based on presence of stamen and pistil:

  • Unisexual Flowers: Flowers which contain either only stamens or only pistil. For example, corn and papaya.
  • Bisexual Flowers: Flowers which contain both stamen and pistil. For example, mustard, rose and others.

Fertililsation

  • Male gametes: Anther contains pollen grains which produce male gamete.
  • Female gamete: Ovary contains one or more ovules. Female gamete is formed in an ovule.
  • The fusion of male gamete and the female gamete is called fertilisation.
  • Fertilised egg is called zygote. Zygote develops into embryo.

Pollination

  • The transfer of pollen from the anther to the stigma of a flower is called pollination.
  • Self-pollination: If the pollen lands on the stigma of the flower or another flower of the same plant.
  • Cross-pollination: When the pollen of a flower lands on the stigma of flower of different plant of same kind.

Fruit and Seed Formation

After fertilisation, the ovary grows into a fruit and other parts of the flower fall off.

The fruit is the ripened ovary. Fruit implies the edible part of the plant.

Four types of fruits on the arrangement are:

  • Simple fruit: It develops from single ovary of a single flower and may be fleshy or dry. For example, tomato, banana.
  • Aggregate fruit: It consist of a mass of small drupes each of which develop from separate ovary of a single flower. For example: raspberry and strawberry.
  • Composite fruit: It develops from the ovaries of many flowers growing in a cluster. For example, Jackfruit and Pineapple.
  • Accessory fruit: It contains tissue derived from plant parts other than the ovary. For example, Apple and pear.
The seed develops from the ovules.

The seed contains an embryo which is enclosed in a protective seed coat. Seed coat is the outer part of the seed. For example, mango seed has white colour seed coat, if you break it up, you will find seeds inside it.

Question?

Is almond a fruit of seed?

Seed dispersal

  • Seed dispersal is aided by wind, water and animals.
  • Seed dispersal help the plants to:
    • Prevent overcrowding
    • Avoid competition for sunlight, water and minerals.
    • Invade new habitats.

Stem

  • Stem is the growing part of the plant. It is erect, strong and grows away from the soil and towards the light.
  • Leaves and branches arise from nodes.
  • Stems are divided into different regions between the nodes.
  • Apical bud: It is the growing apex of the stem is covered by numerous, tiny, developing leaves.

Functions of Stem:

  • To support and hold leaves, flowers and fruits.
  • It conducts the water and minerals from roots to leaves and fruits.
  • It also helps in storing food.
  • It also helps in process of Photosynthesis.

Three types of Stem:

  • Underground Stem:
    • Stems remain in the ground.
    • They produce aerial shoots annually.
    • Some of the forms are:
    • Tuber – ex. Potato
    • Corm – ex. Saffron
    • Bulb – ex. Onion
    • Rhizome -- Ginger
  • Aerial Stem:
    • Some of the forms are:
    • Stem tendril – ex. Passiflora
    • Pylloclade – ex. Duranta
  • Sub-aerial Stem:
    • Some of the forms are:
    • Runner – ex. Doob grass
    • Stolon – ex. Jasmine

Leaf

  • It is green outgrowth from the stem.
  • It is the primary site for photosynthesis i.e. prepare food for the plant.
  • Leaf are initiated in the apical bud (growing tip of a stem).
  • Leaf of Aloe vera has liquid inside them.
  • Leaves of cactus are modified into spines.