Neptunia lutea

Yellow-puff
Flower, flower bud, and foliage
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Fabales
Family:	Fabaceae
Subfamily:	Mimosoideae
Genus:	Neptunia
Species:	N. lutea
Binomial name
Neptunia lutea (Leavenworth) Benth.

Neptunia lutea, the yellow-puff, is a trailing, vine-like perennial plant of the legume family Fabaeceae. Its stems are covered with soft spines, but is not nearly as prickly as its cousin, the sensitive brier (Mimosa nuttallii).

The sprawling stems of this plant branch frequently, with each branch growing as long as 5 ft. Leaves are alternate and stalked, bipinnate, looking much like tiny fern fronds. The flowers are tiny and arranged in a slightly elongated, congested bundle (inflorescence) containing 30-60 flowers each. The unopened bud clusters look much like green bramble fruits. Each individual flower has five minute pedals and ten stamens. When the flowers open, the inflorescence looks like a puffy yellow ball, with usually only the long yellow stamens visible. The inflorescence rests solitary at the end of a slender stalk.

This plant grows best in full sun to partial shade. It inhabits the various soils of forest margins, the openings of thickets, roadsides, prairies and pastures.

Like the related sensitive plant and sensitive brier, the leaves of this plant exhibit rapid plant movement. They will close upon touch, as well as at night and during periods of cloudy weather.

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Wikipedia