Question

Pollinia occur in
A) Cruciferae
B) Asteraceae
C) Poaceae
D) Asclepiadaceae

Answer 1

Pollen grains are small and microscopic structures which represent and carry the male reproductive part of the plant. They are produced in another. When pollen grains are found in a sac-like structure, it is called pollinium.

Complete answer:
Asclepiadaceae is commonly known as the milkweed family.

Option A: Cruciferae or Brassicaceae is one of the important families of flowering plants. Their pollen grains are tricolpate. Their shape varies from prolate spheroidal, subprolate to prolate. The pollen grains are not found in a sac-like structure. Therefore, this is an incorrect option.

Option B: Asteraceae is one of the largest angiosperm families. The pollen grains belonging to this family are unique in being characteristically echinate. Therefore, this is an incorrect option.

Option C: Poaceae or Gramineae is a large family of monocotyledonous flowering plants known as grasses. Here, pollen grains are arranged as monads, with a single pore-type aperture. Therefore, this is an incorrect option.

Option D: Asclepiadaceae (milkweed) family is characterised by the presence of pollinia. All the pollen grains from each lobe of the anther are agglutinated to form a granular mass called pollinium. Pollinium from both the lobes forms pollinia. These are connected with each other via retinacula and corpusculum, together called translators. The pollen grains in the pollinia are pollinated as a single unit. Therefore, this is the correct option.

Hence the correct answer is option ‘D’.

Note: It is to be noted that the parts of the pollinia stick to visiting insect pollinators. These visitors then carry them to other flowers to facilitate cross-pollination which is one of the two types of pollination. The other type of pollination is self pollination.