Question

What is true of the androecium of Fabaceae?
(a) Ten free
(b) 10 Monadelphous
(c) 10 diadelphous
(d) 10 polyadelphous

Answer 1

Hint: Fabaceae is the family of a number of legumes and pulses which increases the fertility of soil due to the presence of root nodules. Androecium or stamens represent the male reproductive organ of a flower.

Complete answer:
In the family of Fabaceae or Papilionaceae, the androecium is ten and usually diadelphous. It is a condition wherein the stamens are fused by their filaments while the anthers are free. In diadelphous condition, the fusion of filaments produces a group of two. The fused filaments may be in 1+9 condition where one group consists of only a single stamen while the rest 9 are fused in another group. E.g. Lathyrus. Another combination may be a 5+5 pattern wherein the two bundles of fused filaments is observed. E.g. Aeschynomene.

Additional Information: Some features of the Fabaceae family are:
-A wide variety of herbs e.g Melilotus, shrubs e.g. Tephrosia, climbers e.g. Lathyrus, twiners and trees e.g. Dalbergia are observed spread over mesophytic, xerophytic and halophytic conditions.
-A branched tap root system with nodules exhibiting symbiotic association with nitrogen-fixing bacteria Rhizobium is observed.
-The phyllotaxy is alternate and rarely whorled or opposite. Certain plants show the modification of leaves into tendrils like Pisum.
-Racemose inflorescence with bracteate or ebracteate flowers that may possess pedicel i.e pedicellate or not i.e sessile. The flowers are zygomorphic.
-The calyx is composed of five fused sepals with imbricate aestivation.
-The corolla consists of five free petals arranged in descending imbricate aestivation.
-A monocarpellary gynoecium with the superior unilocular ovary and marginal placentation is noted.
So, the correct answer is ‘10 Diadelphous.’

Note: Some important terms to remember:
-Phyllotaxy: The pattern and arrangement of leaves on a stem or its branch are known as phyllotaxy.
-Aestivation: It represents the composition of sepals and petals relative to one another. In imbricate aestivation, irregular overlapping of petals or sepals occurs over one another.
-Zygomorphic flower: When two halves of the flower can be observed from only one plane through its center.