Question

in entomophilous plant exine of pollen grain are spiny​

Answer 1

Explanation:

Some plants produce echinate pollen, i.e. pollen grains with spines. Spiny pollen grains are known from many species of the Malvaceae, some species of the Convolvulaceae, Cucurbitaceae and Asteraceae.

Answer 2

Explanation:

$\tt\pink{\underline{Exine}}$

→ It age outer layer of pollen grain and very hard.

→ It age made up of sporopollenin in which is most resistance organic material present in nature .

→Sporopollenin is Resistance to high temperatures stronger acids and alkaline and also to enzyme .