''Stylosanthes biflora'', known by the common names pencil flower,
sidebeak pencilflower,
and endbeak pencilflower,
is a species of
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
in the
(legume) family. It is native to the
Southeastern United States
The Southeastern United States, also referred to as the American Southeast or simply the Southeast, is a geographical region of the United States. It is located broadly on the eastern portion of the southern United States and the southern por ...
where it is widespread in open areas of native vegetation. It produces yellow-orange flowers in the summer and fall.
This species is highly variable throughout its range, and numerous species had previously been segregated out of it. However, their morphological differences have been found to be so overlapping that the former segregates are now considered the same species.
Description
''S. biflora'' is a branching
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
that grows tall. The stems are wiry, round, hairy, and light to medium green. Each compound leaf has three leaflets (
trifoliate
The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...
) and are alternate on the stems. The leaflets measure long and are elliptic in shape. They have smooth margins. A pair of partly joined
bracts
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...
, or
stipules
In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...
, tapering to a beak, surrounds the base of each
petiole and part of the adjacent stem.
The flowers are orange to yellow and are similar to others in the pea family. The
petals
Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually ...
consist of large standard top) petal and smaller wings and keel, subtended by bracts.
The flowers are nearly circular in shape.
Distribution and habitat
The species is native in the United States from Texas to the west, Illinois to the north, New York to the east, and Florida to the south. It is also present in Arizona.
Its habitats include sunny and dry areas, such as glades, prairies, savannas, dry upland forests, tops of bluffs, and riverbanks.
Ecology
The flowers bloom May to September and are visited by bees and butterflies. It is a host plant for the barred yellow butterfly (
Eurema daira
''Eurema daira'', the fairy yellow, barred yellow or barred sulphur, is a butterfly
Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large ...
).
References
{{Taxonbar, from=Q15542860
biflora
Flora of the Southeastern United States