CUPPLANT INDIANCUP RAGGED CUP ROSINPLANT
(Silphium perfoliatum) Thistle family
Plower-heads - Yellow, nearly flat; 2 to 3 in. across; 20 to 30
narrow, pistillate ray florets, about 1 in. long, overlapping in
2 or 3 series around the perfect but sterile disk florets. Stem:
4 to 8 ft.
tall, square, smooth, usually branched above.
Leaves: Opposite, ovate, upper ones united by their bases to form
a cup; lower ones large, coarsely toothed, and narrowed into
margined petioles; all filled with resinous juice.
Preferred Habitat - Moist soil, low ground near streams.
Flowering Season - July-September.
Distribution - Ontario, New York, and Georgia, westward to
Minnesota, Nebraska, and Louisiana.
It behooves a species related to the wonderful compass-plant
(q.v.) to do something unusual with its leaves; hence this one
makes cups to catch rain by uniting its upper pairs. Darwin's
experiments with infinitesimal doses of ammonia in stimulating
leaf activity may throw some light on this singular arrangement.
So many plants provide traps to catch rain, although fourteen
gallons of it contain only one grain of ammonia, that we must
believe there is a wise physiological reason for calling upon the
leaves to assist the roots in absorbing it, A native of Western
prairies, the cup-plant has now become naturalized so far east as
the neighborhood 6f New York City.
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