Morphology of Flowering Plants

Stem:

  • Bears branches, leaves, flowers, and fruits
  • Conducts water and minerals to all parts of the plant body
  • Bears nodes and internodes

Stem modifications:

  • For storage- Example: Potato, ginger, turmeric.
  • For support- Tendrils in cucumber, pumpkins, watermelon.
  • For protection- thorns in Citrus, Bougainvillea.
  • For vegetative propagation- Tubers and rhizomes in potato and ginger respectively.

Leaf:

  • Performs the function of photosynthesis
  • Consists of leaf base, petiole, and lamina
  • Veins help in the transport of water to all leaf parts.
  • Arrangement of veins is known as venation.
  • Parallel venation is found in monocots. Example: Banana
  • Reticulate venation is found in dicots. Example: Mango
  • Leaves may be simple or compound.
  • Pattern of arrangement of leaves on the stem is known as phyllotaxy. It may be alternate as in china rose, opposite as in Calotropis or whorled as in Alstonia.

Leaf modifications:

  • Tendrils- Example: Peas
  • Spines- Example: Cactus
  • Fleshy leaves for storage- Example: Onion and garlic

Nflorescence:

  • Arrangement of flowers on the floral axis is termed as inflorescence.
  • Racemose- In this, main axis continuous to grow and flowers are borne laterally.
  • Cymose- In this, main axis terminates in a flower.

Flower:

  • Flower is the reproductive unit in angiosperms.
  • Bisexual flower has both androecium and gynoecium.
  • Unisexual flower has either androecium or gynoecium.
  • Actinomorphic flower has radial symmetry. Example: Datura and mustard
  • Zygomorphic flower has bilateral symmetry. Example: Pea and bean
  • Asymmetric flower cannot divided into similar halves by any vertical plane. Example: Canna

Parts of flower:

  • Calyx is outermost whorl of a flower composed of sepals. It may be gamosepalous united sepals or polysepalus free sepals.
  • Corolla is composed of petals. Petals are brightly coloured to attract pollinators. It may be gamopetalous united petals or polypetalous free petals.
  • Androecium is the male reproductive part of a flower, composed of stamens.
  • Based on attachment of anther with floral parts, it can be epiphyllous attached with perianth or epipetalus attached with petals.
  • Spamens can be monoadelphous united in one bundle, diadelphous united in two bundles, and polyadelphous united with petals.
  • Stamens can be monoadelphous united in one bundle, diadelphous united in two bundles, and polyadelphous united in many bundles.
  • A sterile stamen is called a staminode.
  • Gynoecium is the female reproductive part of a flower, composed of pistil.
  • Based on position of ovary, a flower can be hypogynous ovary is  superior, perigynous or epigynous ovary is inferior.

Whorls of a Flower:

When carpels are fused, ovary is syncarpous; when carpels are free, ovary is apocarous.

  • Aestivation is the arrangement of sepals and petals in a flower bud. It may be
  • Valvate- Example: Calotropis
  • Twisted- Example: China rose
  • Imbricate- Example: Cassia
  • Vexillary- Example: Pea
  • Placentation is arrangement of ovules within the ovary. It can be
  • Marginal – Example: Pea
  • Axile – Example: Tomato
  • Parietal – Example: Mustard
  • Free central – Example: Dianthus
  • Basal – Example: Sunflower

Floral Formulae:

Floral formulae are represented by symbols. Some of them are:-

Br

Bracteate

K

Calyx

C

Corolla

P

Perianth

A

Androecium

G

Gynoecium

G

Superior ovary

`G

Inferior ovary

Male

Female

Bisexual

Å

Actinomorphic

%

Zygomorphic

Enclosing figure within brackets

Fusion

Line drawn symbols of floral parts

Adhesion

 

  • Fruit is the matured ovary developed after fertilization. Parthenocarpic fruits: Fruits formed without fertilization on ovary. Parts of fruits:

  • On the basis of origin, fruits are classified as: True fruits
  • False fruits based on floral arrangements true fruits are further classified as:

 

Seed Germination:

  • It is the process of the seed develops into an individual plant utilizing the reserve nutrients present in the cotyledons.

Conditions necessary for germination:

  • Water
  • Oxygen
  • Favourable temperature

Process of germination:

  1. The seed takes up water and swells.
  2. The embryonic radicle and plumule start growing and force the seed coat to rupture.
  3. The radicle comes out first and form the root followed by the plumule which develops into the shoot.

Types of germination:

  1. Epigeal germination: In this method the  cotyledons are lifted above the ground and they act as the first leaves as a result of the rapid elongation of the hypocotyls. It takes place in seeds like Caster, cotton, sunflower etc.
  2. Hypogeal germination: In this germination the cotyledons remain inside the soil and the epicotyls elongates and pushes the plumule above. It takes place in seeds like pea, maize, mango etc.

Family Solanacesa:

  • Floral characters include:

Inflorescence : Solitary, axillary or cymose

Flower : Bisexual and actinomorphic

Calyx : Five sepals, gamosepalous, valvate aestivation

Corolla : Five petals, gamopetalous, valvate aestivation

Androecium : Five stamens, epipetalous

Gynoecium : Bicarpellary, syncarpous, superior ovary, bilocular, many ovules

Fruit : Berry or capsule

Floral diagram

Family Fabaceae:

  • Floral characters include:

Inflorescence : Racemose

Keels 2

Vexillary aestivation.

Androecium : Ten, diadelphous, anther dithecous

Floral formula :

Floral diagram:

Family Liliaceae:

  • Floral characters include:

Inflorescence : Solitary, cymose

Axile placentation

Floral formula:

Related Keywords
11    PMT    Biology    Morphology of Flowering Plants    Short Notes