STUDIES OF TROPICAL CAN PHANEROGAMS— 
JL 
By Pavut C. STANDLEY. 
INTRODUCTION. 
The present paper introduces a series which is intended to include 
notes upon plants of tropical and subtropical North and South 
America and descriptions of miscellaneous new species, as also tax- 
onomic reviews of some of the smaller genera. The plants discussed 
in the first installment are some which were studied by the writer 
while preparing a report upon certain families for a proposed flora 
of Panama. They belong to the Cyperaceae, Gentianaceae, Rubia- 
ceae, and the families formerly associated as the Leguminosae. The 
determination of the Panaman species of Sommera, Watsonamra, 
and Cobaea has necessitated a revision of these genera, the results of 
which are here published. Most of the new species are from the large 
collections made by Mr. H. Pittier in Colombia and in Central 
America, especially in Costa Rica. 
Unless otherwise indicated, all specimens cited are in the United 
States National Herbarium. 
TWO NEW SPECIES OF DICHROMENA. 
Dichromena is one of the smaller genera of the Cyperaceae, but 
several of its species have a wide distribution in tropical America. 
The two species described here are apparently of limited distribution. 
Dichromena pittieri Standley, sp. nov. 
Perennial from a cluster of fibrous roots; leaves very numerous, flat, 8 to 15 
cm. long, 2 to 4 mm. wide, attenuate, not dilated at the base, pale grayish green, 
densely velvety-pubescent on both surfaces with short, very fine hairs; culms 
numerous, obtusely angled, slender, slightly surpassing the leaves, 16 to 21 cm. 
high, densely pubescent; bracts of the inflorescence about 6, 2 to 10 cm. long, 
often with a few very short additional ones, about as wide as the leaves, 
slightly discolored at the base and ciliate, elsewhere finely and densely pubes- 
cent; spikelets numerous, 8 to 12, 4.5 to 5 mm. long, densely capitate, the whole 
head about 1 cm. in diameter; scales white, glabrous, oblong, ovate, or lanceo- 
late, acute, thick and firm, prominently keeled but without other evident nerves ; 
style linear, the branches much elongated; achene about 1 mm. long, broadly 
obovoid, brownish white, shining, very finely and rather obscurely transversely 
undulate; beak broadly pyramidal, about one-fourth as long as the achene. 
427 
