Fabaceae
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This is a huge and very important family in the tropics, containing everything from aquatic plants to shrubs to emergent trees. The Fabaceae are traditionally divided into three subfamilies, which are sometimes treated individually at the family level: Caesalpinioideae, Mimosoideae, and Papilionoideae (=Faboideae). All Fabaceae have alternate leaves with stipules, and almost all the species are pinnately compound-leaved except for the bifid-leaved Bauhinia (Caesalpinioideae) and the unifoliolate Swartzia simplex (Papilionoideae). There is a distinctive green pea smell from the broken petiole of all Fabaceae.
Esta es una familia inmensa y muy importante en las zonas tropicales, que contiene plantas acuáticas, hierbas, arbustos y hasta árboles emergentes. Las Fabaceas tradicionalmente se dividen en tres subfamilias, que a veces se considera familias separadas: Caesalpinioideae, Mimosoideae, y Papilionoideae (=Faboideae). Todas las Fabaceas tienen hojas alternas con estípulas, y casi todas tienen hojas pinnaticompuestas. Algunas excepciones son el género Bauhinia (Caesalpinioideae) con hojas bífidas y Swartzia simplex (Papilionoideae) con hojas unifolioladas. El pecíolo roto de todas las Fabaceas tiene un olor distintivo a habichuela.
Three subfamilies are easily distinguished by their flowers and, to a lesser extent, by their fruits. Note: Subfamily names end in “oideae”. All members are united by their “pea pod” fruit known as a legume (technically a dehiscent dry fruit that splits along two seams).
Mimosoideae – most conspicuous parts of the flower are the stamens, inflorescence resembles a powderpuff.
Caesalpinioideae – petals are the conspicuous part of the flower, 5 petals more or less equal in size and shape. Fruit (legume) has seeds arranged transversely, somewhat like a roll of life-savrs.
Papilionoideae – “butterfly” or pea flowers, bilaterally symmetrical, 5 petals: upright banner, two lateral wings, a keel formed by two petals fused at tip and free at base, 9+1 arrangement of stamens, fruit sometimes flattened into wing-like pods.
QUICK KEY TO THE FABACEAE BASED ON LEAVES (prepared by Dr. Humberto Jimenez-Saa for his Tropical Dendrology course)
1. Leaves simple bilobed = Bauhinia (Caesalpinioideae)
2. Leaves bifoliate
- a. Hymenaea
- b. Cynometra
- c. Petogyne
- d. Macrolobium
3. Leaves paripinnate (even number of leaflets) with nectaries
- a. Inga (Mimosoideae)
- b. Senna (Caesalpinioideae)
- c. Cassia (Caesalpinioideae)
4. Leaves paripinnate (even number of leaflets) without nectaries = Caesalpinioideae
5. Leaves imparipinnate trifoliate with stipels and sometimes with spines = Erythrina (Papilionoideae)
6. Imparipinnate, petiolules thicker than rachis = Papilionoideae
7. Bipinnate with nectaries = Mimosoideae
8. Bipinnate without nectaries = Caesalpinioideae
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