1. Elaeagnus L. (oleaster)
Plants shrubs or
small trees, with a dense covering of silvery or rusty, peltate or stellate,
scales or hairs on leaves, twigs, and buds. Leaves alternate, short-petiolate.
Stipules absent. Leaf blades simple, the margins entire. Inflorescences small
clusters of flowers or solitary flowers in the leaf axils. Flowers perfect but
sometimes functionally unisexual, deeply perigynous, the receptacle elongated
into a tubular or funnelform hypanthium with a pronounced constriction just
above the ovary (which thus appears inferior), the nongreen portion above the
ovary shed before fruiting. Sepals (3)4(–6), petaloid, spreading, similar in
texture to the hypanthium, with stellate hairs at the tips. Stamens 4, attached
near the tip of the hypanthium alternating with the sepals, the filaments very
short. Petals absent. Ovary superior, 1-locular, with 1 ovule. Style 1, linear,
with the stigma a linear area along the side toward the tip. Fruits achenes,
but appearing drupelike or berrylike, the achene enclosed by (but not fused
with) the expanded fleshy receptacle. About 40 species, North America, Europe,
Asia.
The flowers of Elaeagnus
have a strong, sweet fragrance and are unusual in that the hypanthium changes
color and texture above the ovary, appearing confusingly similar to a corolla
tube with four lobes at the tip. The fruits are similarly confusing, as the
base of the hypanthium turns fleshy and berrylike. Roots of most species of Elaeagnus
can form symbiotic relationships with soilborne bacteria of the genus Rhizobium,
which have the ability to fix atmospheric nitrogen into nitrates that are
absorbed as nutrients by plants, and they thus act to enrich the soil