Morphology of Plants

Morphology of Plants

The study of forms and features of different parts of plants, like roots, stems, leaves, flowers, fruits, etc., is called morphology.

Root

The root is the descending part of the plant which develops from the radicle. Root hairs arise from the epidermis. A root generally grows in the soil away from light.

Types of Roots

Roots are of two types –

1. Taproot

2. Adventitious root

Modification of Tap Roots

1. Conical – like a carrot

2. Napiform – like Turnip, beet, etc.

3. Fusiform – like a radish

A rootless plant is a lemma.

Stem

This is the part of a plant which grows towards light. So, they are usually positively phototrophic. It develops from the plumule.

Functions of Stem

• The stem of the plant helps in distributing food to all parts of the plant.

• Besides this, it also helps in the storing of food.

• Shaping the plant, respiration, and photosynthesis.

Modifications of Stems (Underground)

1. Tuber – like potato.

2. Corm – like Colocasia, saffron, etc.

3. Bulb – like Onion, garlic, etc.

4. Rhizome – like Turmeric, ginger, etc.

Leaf

It is green. Its main function is synthesis of food through photosynthesis.

• In cacti, leaves are modified into spines.

• Cacti are referred to as xerophytes.

• Phyllotaxy refers to the pattern of arrangement of leaves.

Flower

Clove is obtained from flower buds. The flower is the reproductive part of the plant.

In a flower, the calyx, corolla, androecium, and gynoecium are found.

• The androecium is the male sex organ.

• The gynoecium is the female sex organ.

Androecium

• The unit of the androecium is the stamen.

• There are one or more stamens in the androecium.

• Pollen grains are found in anthers.

Gynoecium

• The unit of the gynoecium is the carpel or pistil.

Parts of Carpel

1. Ovary

2. Style

3. Stigma

• A flower having both stamen and carpel is called a bisexual flower.

Pollination

After maturation of the anther, the process of transfer of pollen grains to the stigma is called pollination.

Types of Pollination

1. Self-pollination

2. Cross-pollination

Fertilization

Fusion of male and female gametes forming a zygote is called fertilisation in living organisms.

• In the case of flowering plants, a unique event, double fertilisation, takes place.

• In this process, after germination of the pollen grain, the pollen tube reaches into the embryosac, releasing two male gametes.

• One male gamete fuses with the egg cell (i.e., female gamete) to form a zygote, whereas the other gamete fuses with polar nuclei to form endosperm (triple fusion).

• This complete process is called double fertilisation.

Syngamy

• Fusion of gametes resulting in the formation of a diploid zygote is called syngamy.

Parthenocarpy

• In some plants, fruits are developed from the ovary without fertilisation. This type of fruit is called parthenocarpy. Normally these types of fruits are seedless.

  • Example – Banana, Papaya, Orange, grapes, pineapple, etc.

• In the majority of flowering plants, out of four megaspores, the ratio of functional and degenerate megaspores is 1 : 3.

• Parthenogenesis, apogamy, and sporophytic budding are irregular modes of reproduction resulting in the development of an embryo without fertilisation.

• A bulbil takes part in vegetative reproduction.

• The inflorescence of wheat is a spike.

• Photoperiodism affects the flowering of plants.

• Pollination in maize takes place by air.

• The male part of the flower is the stamen, whereas the female part of the flower is the pistil.

• The relationship between a flower and a honeybee will help the flower in pollination.

• A node is the part of the stem where a leaf arises.

• Pollination by wind is known as anemophily.

Importance of Flowers

• Currently, there is increased demand for fresh and good-quality flowers for human consumption worldwide due to –

  • Flowers are endowed with natural antioxidants and scavenging of reactive oxygen radicals.

  • Flowers are a rich source of anthocyanins.

  • Flowers are an important source of vitamins and minerals.

• The plants of papaya have unisexual flowers.

Formation of Fruits

Fruit is a matured or ripened ovary developed after fertilisation.

• Formation of fruit takes place from the ovary.

Types of Fruits

1. Simple fruits – like Banana, guavas, etc.

2. Aggregate fruit – Strawberry, Custard apple, etc.

3. Composite fruit – Jackfruit, Mulberry etc.

• In the development of some fruits, the calyx, corolla, and thalamus take part.

• These types of fruits are called false fruits. Example – Apple, Jackfruit, Pear etc.

Some Fruits and Their Edible Parts

• The presence of more than one embryo in a seed is called polyembryony.

• The best example of polyembryony is citrus fruit.

• Water of coconut is liquid nucellus.

• The medicinal plant used in the preparation of skincare is aloe vera.

• In the seed of neem, major pesticidal properties are present.

• The alkaloid naturally found in coffee, cocoa, and kola nut is caffeine.

• Hot peppers are hot due to the presence of capsaicin.

• A clone is a group of genetically identical individuals obtained through micropropagation.

• The place of origin of maize is America.

• Seedless fruits are of no use in coconut and pomegranate.

• Papaya is the source of papain.

• Vivipary germination is found in mangrove plants.

• Morphine is a narcotic analgesic drug.

Final Thoughts

Morphology is the study of the structure and form of different plant parts such as roots, stems, leaves, flowers, and fruits. Roots can be tap or adventitious and may be modified into forms like carrot (conical) or turnip (napiform). Stems grow towards light, support the plant, store food, and can develop into tubers, bulbs, or rhizomes.

Leaves are mainly green for photosynthesis, while flowers serve as reproductive organs, with the androecium as the male and the gynoecium as the female part. Pollination transfers pollen to the stigma, leading to fertilisation, often involving double fertilisation.

Fruits develop from the ovary, and modifications like parthenocarpy result in seedless fruits such as bananas and papayas.