ISC-12>PRACTICAL>OBSERVATION>PLANT MORPHOLOGY

I. STUDY OF INFLORESCENCE

AIM:Identification, drawing and comments on inflorescence
A. RACEMOSE INFLORESCENCE
   Comments :
  1. The main axis continues to grow.
  2. Growing point does not end in flower
  3. The flowers are borne laterally in an acropetal succession.  
(Acropetal succession means that older flowers are at the base and younger flowers are near the apex)
EXAMPLES OF RACEMOSE
Picture
GLADIOLI
B. CYMOSE INFLORESCENCE
  1. The main axis terminates and lateral branches arise.
  2. The main axis terminates in a flower. 
  3. Older flowers are at the apex and younger flowers are near the base. (Basipetal succession)
EXAMPLES OF CYMOSE
C. CAPITULUM
  1. In capitulum inflorescence, the growth of peduncle is retarded and it become broad, flattened concave or convex. 
  2. On it small flowers are found. These flowers are called floret. If all the flower of capitulum are same , then it is called homogamous. 
  3. If two different type of floret, ray floret and disc floret are present in same inflorescence than it is known as heterogamous. In this type of inflorescence florets may be unisexual, bisexual and sterile. 
  4. This inflorescence is surrounded by one or more involucre. It is most advanced type of inflorescence. eg. Sunflower, Zinnia, Marigold, Cosmos.

II. ADAPTATION TO POLLINATION

AIM: To study the flowers adapted to pollination by different agencies.
  • Flowers adapted to pollination by different agencies.
  • Students should be able to identify the type of pollination of the given flower, draw the diagram of the flower and give two reasons for the type of pollination.
A) Insect pollinated flower :
Identification
Diagram
Comments :
  1. Petals: Present, often large, coloured and scented.
  2. Nectar: Produced by nectaries to attract insects
  3. Stamen: Present inside the flower
  4. Pollen: Smaller amount , often round, sticky or have projection to attach to furry bodies of insects.
  5. Stigma: Small surface area, inside the flower
  6. Examples: Rose, sunflower etc
B) Wind pollinated flower :
Male and female inflorescence
Comments
  1. Flowers inconspicuous, non showy and not brightly coloured.
  2. Flowers are devoid of scent and nectar.
  3. Stamens are pendulous and also hang outside the flower.
  4. Anthers are versatile i.e. they are attached at the midpoint, so they will swing freely in the wind.
  5. Pollen are produced in large number.
  6. Stigmas are large, branched and feathery – and held outside the flower