(Leguminosae) Legume or Pea family
- Herbs,shrubs, or trees; extremely versatile in morphology
and ecology; roots often with nitrogen-fixing bacterial nodules (Rhizobium
- Leaves mostly alternate;
pinnately or bipinnately compound; sometimes palmately compound; sometimes
simple by suppression of leaflets (Acacia), reduced to one phyllode.
flattened leaf-like petiole (with no blade) that functions a s leaf, as the primary photosynthetic surface.
enlargement of the petiole of petiolule base at its point of attachment
to the stem, or of the petiole apex at its point of attachment to the
blade. Turgor pressure in adaxial and abaxial surfaces cause the petiole
to collapse or remain outstretched. This is associated with leaf movement.
Leaflets of many legumes open in the day and close at night; in some
spp., like Mimosa, leaflets fold up in response to touch.
(well-defined at base of petiole). Stipules of some species of Acacia, Prosopis (mesquite), Robinia
(locust) develop into spines.
- Flowers zygomorphic or
actinomorphic (Mimosoideae), usually perfect, complete.
5 sepals fused.
5 petals, either distinct or 2 or more petals may be fused.
usually 10 stamens, filaments may be distinct or all united into a tube
(Monadelphous), or 9 united into a strap with one filament free
1 pistil, simple, 1 carpel, ovary superior, usually 1-locular; ovules
- Fruit legume; dehiscent
or not dehiscent (mesquite); sometimes a loment breaking transversely into
1-seeded segments. It may be that the primitive pod (legume) type was one
that dehisced explosively when ripe, scattering seeds (beans) away from
the parent plant. In riparian species, the ejected seeds are buoyant and
further dispersed by streams or river currents. There are many variants of
the basic legume pod inflated buoyant pods, pods that disarticulate in
1-seede segments, pods that adhere to animals. The effectiveness of these
adaptations is evident from the wide ranges of many legume genera, which
span different continents and remote islands.
- Seeds often with
hard seed coats (testa) and capable of long dormancy in soil. Germination
often requires some sort of scarification, either physical nicking when
tumbling down a wash, or chemical erosion while passing thru the
alimentary canal (digestive tract) of various animals. Some sees are
bright red to attract birds; others are enclosed within tasty and
nutritious pods (carob bean, and mesquite). Legumes are uniquely adapted
to colonize infertile soil by their special relationship with Rhizobium bacteria, which inhabit
root nodules and convert abundant, inert atmospheric nitrogen to compounds
plants can absorb (ammonia). Lavish use of nitrogenous compounds is especially
obvious in legume seeds. These usually lack endosperm, but have rich
stores of protein in the cotyledons. This is precious food for herbivores.
Legume seeds are also commonly loaded with alkaloids and other toxic
nitrogenous compounds (Astragalus,
cosmopolitan. Fabaceae is the 3rd largest family of flowering
plants, behind the Asteracea and Orchidaceae.
- Economic plants
Second only to Poaceae (grass family) in economic importance. It is
valuable for its restoration or maintenance of soil fertility; rotation of
leguminous plants with crops that deplete the soil of nitrogen reserves is
an alternative to expensive chemical fertilizers in many regions.
k. Glycine max (soybean)
m. Phaseolus spp. (bean)
n. Pisum sativum (pea)
o. Glycyrrhiza sp. (the source of
p. Pachyrrhizus sp. (jicama)
k. Trifolium (clover)Vicia (vetch)
(locoweed) toxic levels of selenium
Cassia and Senna (alkaloids)
insecticide Rotenone comes from Derris
k. Robinia (locust)
is a large, heterogeneous taxon which is traditionally separated into 3
sub-families: Papilionideae, Caesalpinoideae, Mimosoideae.
- Papilionoideae (or Faboideae)
the largest of the sub-families.
the perianth is composed of 4
zygomorphic corolla, with the
banner enclosing the other petals in bud (aestivation).
k. leaves are pinnately compound, trifoliate, occasionally
reduced to a single leaflet.
androecium of 10 distinct or
fused or diadelphous stamens.
Corolla of 5 parts, slightly zygomorphic, but uppermost
petal (banner) is enclosed with the lateral wings in bud.
Leaves are pinnately, sometimes bipinnately compound.
of 10 stamens or less.
Primarily tropical, with few temperate species.
generally large with conspicuous corollas.
flowers actinomorphic and
Leaves usually bipinnately compound.
of 10-many stamens, often exserted well-beyond the
The unifying feature of
the family is the unicarpellate gynoecium (which develops into a legume) with a
double row of ovules