_Senna Leaves_; F. _Feuilles de Séné_; G. _Sennesblätter_.
=Botanical Origin=—The Senna Leaves of commerce are afforded by two
species of _Cassia_[833] belonging to that section of the genus which
is distinguished by having leaves without glands, axillary racemes
elongating as inflorescence advances, membranaceous bracts which in the
young raceme conceal the flower buds but drop off during flowering, and
a short, broad, flat legume.
The senna plants are low perennial bushy shrubs, 2 to 4 feet high,
having pari-pinnate leaves with leaflets unequal at the base, and
yellow flowers. The pods contain 6 or more seeds in each, suspended
on alternate valves by long capillary funicles. These run towards the
pointed end of the seed, but are curved at their attachment to the
hilum just below. The seeds are compressed and of an obovate-cuneate or
oblong form, beaked at the narrower end.[834]