Botanical Description Of Legumes
PLANT BIOLOGY AND BIOTECHNOLOGY UNIT
DEPARTMENT OF NUTURAL SCIENCE
The word legume is derived from the Latin verb ‘legere’ which means ‘to gather’.
The term pulse has a more direct lineage. It derives from puls or porridge, a cooked bean dish which the ancient Romans were fond of eating.
Legumes mainly called pulses are flowering plants in the family Leguminosae.
This family is also known as Fabaceae, and both terms can be used interchangeably to indicate some 690 genera and 18,000 species therein.
The Leguminosae family is classified into three sub-families:
Each sub-family is identified by its flowers. Edible legume crops are mainly found in the sub-family Papilionoideae.
This includes; soybean, chickpea, bean, and pea, among others. Other lesser known members of the legume family include clover, licorice, lentils, and the peanut.
The peanut is in fact, biologically though not culinary, defined as a woody, indehiscent legume.
Unique to Fabaceae are the flowers and fruit. Like many flowers, those found on legume plants are hermaphroditic, containing both the stamen and pistil.
This makes the plants self-fertile, meaning that an individual plant is able to reproduce by itself which can have the effect of limiting genetic diversity.
However, hybridization occurs frequently in nature due to this characteristic, as any plant can pollinate another due to the hermaphroditic properties therein.
This creates difficulty in clearly defining the differences that enter between subspecies.
The flower typically has five petals and an ovary with one carpel, cavity, and style.
The distinctive nature of the flowers is not in the parts but in the shape of the parts.
The general pattern of legume flowers follows that of the pea blossom.
The result of this arrangement is that of a papilionaceous design, which means butterfly like.
The petals of the legume plant are shaped into a cup. One large petal (the banner or standard) folds over the rest for protection.
In front of this petal are two narrower petals called wings between which two other petals unite.
Due to their shape these petals are referred to as the keel.
Within that fold are the stamens and pistil.
The interesting part is that after pollination the flower will die and reveal the growing ovary which becomes the pod.