PULSE FAMILY LEGUMINOSAE 
PURPLE PRAIRIE CLOVER 
Petalostemum purpureum (Vent.) Rydb. 
The structure of these flowers differs markedly from 
that of any other genus in the family. The calyx is nearly 
equally 5-toothed and somewhat hairy. There are only 5 
stamens and their filaments are 
united to form a sheath which is 
cleft down 1 side. Four of the 
white petals are nearly alike and 
are borne at the top of the stamen 
sheath, whereas the fifth is nearly 
round or heart shaped and in- 
serted in the base of the calyx. 
The genus name Petalostemum 
comes from the combination of 
two Greek words meaning petal 
and stamen, and refers to the 
peculiar union of these parts. 
This smooth herb inhabits dry 
prairies from Indiana and Louisiana 
to the Rocky mountains and Mani- 
toba. It grows 1-3 feet high, gener- 
ally in small clumps and frequently 
along with its relative White Prairie 
Clover, page 167. It is abundant 
along railroads. 
The numerous small leaves, often 
so thickly clustered as to conceal the 
stiff and slender stems, have 5-9 
very narrow leaflets about one-half inch long and sharp tipped. 
The flowers are in dense cylindric spikes one-half inch thick 
and up to 2 inches long. The calyx has § ovate, pointed sepals, 
and is silky hairy. The corolla is purple, slightly more than 
one-eighth inch long; the standard is heart shaped, and wings 
and the keel are oblong. 
CLOVER 
Little masters, hat in hand, Tell me—for I long to know— 
Let me in your presence stand, How, in darkness there below, 
Till your silence solve for me Was your fairy fabric spun, 
This your threefold mystery. Spread and fashioned, three in one. 
166 
