Leguminosae, or Fabaceae - legume family
Belong to rosids (Rosidae). Up to 17,000 species, third largest angiosperm family after Compositae (aster family) and Orchidaceae (orchids). Widely distributed throughout the world, but preferably in tropics. Have root nodules with nitrogen-fixing bacteria. Leaves alternate, pinnately compound (once or twice), with stipules.
Three subfamilies (Caesalpinioideae, Mimosoideae, Papilionoideae) often treated as separate families. Sepals 5, united. Petals 5, in Papilionoideae they are free, unequal and have special names: banner, keel and wing (Fig. 8.19), in Mimosoideae they fuse and form tube. Stamens often 10 with 9 fused and one free stamen; in Mimosoideae, stamens are numerous. Singe pistil with single carpel. Flower formula of Mimosoideae is
Papilionoid legumes have formula like
Fruit is a legume (pod): dehiscent with one camera. Mature seeds without endosperm.
Representatives of Leguminosae:
• Mimosoideae: stamens numerous, petals connected
– Acacia—dominant tree of African and Australian savannas, often withphyllodes
– Mimosa—sensitive plant
• Papilionoideae: stamens 9+1, petals free; this subfamily contains many extremely important food plants with high protein value
– Arachis—peanut with self-buried fruits
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