A delicate-looking plant with Mimosa-like leaves that quickly colonizes
recently disturbed or burned areas. These were growing in Schenley Park,
in a section of former lawn that is being allowed to grow into a meadow
for better water retention. The cheery yellow flowers can keep coming for
months; these were blooming in the middle of September.
Gray, like most older references, puts this species in the genus Cassia.
Here is his description:
CASSIA [Tourn.] L. SENNA. Sepals 5, scarcely united at base. Petals 5,
little unequal, spreading. Stamens 5-10, unequal, and some of them often
imperfect, spreading; anthers opening by 2 pores or chinks at the apex.
Pod many-seeded, often with croes partitions. — Herbs (in the United
States), with simply and abruptly pinnate leaves, and mostly yellow
flowers. (An ancient name of obscure derivation.)
Leaflets small, somewhat sensitive to the touch; stipules striate,
persistent; a cup-shaped gland beneath the lowest pair of leaflets;
anthers all perfect; flowers in small clusters above the axils; pods flat.
C. Chamaecrista L. (PARTRIDGE PEA.) Annual, suberect; branches
usually simple, ascending; pubescence subappressed, usually scanty;
leaflets 10-15 pairs, linear-oblong, oblique at the base; flowers (large)
on slender pedicels, 2 or 3 of the showy yellow petals often with a purple
spot at base; anthers 10, elongated, unequal (4 of them yellow, the others
purple); style slender. — Sandy fields, Mass. to Minn., and southw.,
except in the upland regions. July-Sept.
