42 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 
12. Panicum molle Swartz. 
Panicum molle Swartz, Prodr. Veg. Ind. Occ. 22. 1788. ‘‘ India occidentalis.’’ The 
type, in the Swartz Herbarium, has already been discussed.2 The sterile lemma 
bears in its axis a well-developed palea. There is some uncertainty as to the original 
locality of the type specimen of P. molle. It is said by Swartz to come from the West 
Indies, but we have seen no other specimens of this species from that region. 
Panicum velutinosum Nees; Trin. Gram. Pan. 144. 1826. This is given as a syn- 
onym of Panicum petiverit Trin. 8. Trinius’s specimen was from “‘Brasil,’”? commu- 
nicated by “N. as Esens.”’ This is in the Trinius Herbarium and is the original of 
the plate? of P. velutinosum in the Icones. The spikelets differ from those of the type 
of P. molle in that the palea of the sterile lemma is wanting. Nees¢ later described 
P. velutinosum, giving the locality as follows: ‘‘ Habitat in sylvaticis prope Villa da 
Cachoeira, provinciae Bahiensis.”’ [Brazil]. His specimen, of which Trinius’s is evi- 
dently a duplicate, is in the Munich Herbarium. There are six plants on the sheet, 
all much smaller than Swartz’s plant, and having shorter, broader blades. The 
Argentine specimens, which have been referred to P. velutinosum, have a well- 
developed palea in the sterile floret. Doell@ recognized the two species as distinct 
chiefly because of this character. More material is needed definitely to determine 
whether or not these two forms should be segregated. 
In Kunth’s Enumeratioé the name is misprinted P. velutinum Nees. 
DESCRIPTION. 
Plants ascending or spreading from a decumbent base, usually branching; culms 
30 to 70 cm. high, softly pubescent, at least below the pubescent nodes; sheaths usu- 
ally shorter than the internodes, loose, 
softly pubescent between the nerves, 
sometimes obscurely so, densely ciliate; 
ligule a dense ring of hairs about 1 mm. 
long; blades ascending or spreading, 4 to 
15 cm. long, rarely longer, 7 to 15 mm. 
wide, rounded at the base, finely and 
softly pubescent on both surfaces or 
nearly glabrous on the upper; panicles 
short-exserted or, especially those of the 
branches, included at base, 6 to 15 cm. 
long, the several to many subracemose 
branches ascending, rarely widely spread- 
ing at maturity, the main axis and those 
of the branches densely softly pubescent and also beset with stiff, spreading hairs 
about | mm. long, the short pedicels of the somewhat crowded spikelets similarly 
hirsute; spikelets 3.4 to 3.8 mm. long, 1.5 to 1.7 mm. wide, obovate, turgid, abruptly 
pointed, short-attenuate at base, a distinct internode of the rachilla between the 
first and second glumes; first glume clasping, half as long as the spikelet or more, 
acute, 5-nerved, the nerves usually anastomosing toward the apex, pilose; second 
glume and sterile lemma pointed beyond the fruit, 5-nerved, obscurely reticulated 
between the nerves, pilose, often densely so; fruit 2.6 to 3 mm. long, 1.5 to 1.6 mm. 
wide, elliptic, apiculate. 
The Argentine specimens are less velvety and approach in appearance the large 
forms of P. arizonicum, but these as well as the Mexican specimens lack the papillae 
commonly present on the sheaths of P. arizonicum. 
Fig. 23.—P, molle. From type specimen. 
@ See footnote ¢, p. 36. ¢ Agrost. Bras. 121. 1829. 
6 Trin. Gram. Icon. 2: pl. 180. 1829. @d Mart. Fl. Bras. 2*: 187. 1877. 
¢ Enum. Pl. 1: 92. 1833. 
