43 



Type collected by Rol)ert Combs, No. 583, for whom the species is named, in damp, 



fertile flat woods at Chipley, Washington County, Florida, August 20, 1898. A 



specimen, No. 571, collected August 19, in water of a cypress pond is referred 



here. 

 P. comlmi belongs to the group including P. agrostoidrs INIuhl. and P. longifolium 



Torr., but is separated from these by its low tufted habit, shorter, narrow leaves, 



long, slender spikelets, and elongated lower glume. 

 ARISTIDA COMBSIIsp. nov. (Fig. 17.) 



A tall, strict, leafy perennial, 8 to 12 dm. high, with long, rigid leaves and large com- 

 pound panicles. Culms 



simple, terete, smooth. 



Sheaths longer than the 



internodes, smooth, 



striate, 1 to 1.5 dm. long, 



lower mostl y purple; 



ligule a very short ring; 



leaf-blades linear, rigid, 



erect, attenuate into a 



long subulate point, 3 to 



6 dm. long, 2 to 4 mm. 



wide, fiat or semi-invo- 

 lute, smooth below, sca- 

 brous and somewhat 



glaucous above. Panicle 



large, 4 to 6 dm. long, 



strict or somewhat flex- 



uous; rachis scabrous; 



branches long, ascending 



or suberect, straight or 



flexuous, compound, sca- 

 brous, single or in pairs, 



one short and ft vv-flow- 



ered, the lower longer 



ones 1 to 2.5 dm. in 



length, naked at the 



base for one-fourth their 



length. Spikelets in 



pairs, one almost sessile, 



the other on a pedicel 



one-half as long as the 



spikelet; empty glumes 



lanceolate, one -nerved, 



9 to 10 mm. long, inclu- 

 ding awns, subequal or Fig. \1.—Aristida combsii Scribii. it Ball: a, spikelet; 6, palea. 



the upper usually 0.5 to 



1 mm. longer, scabrous on the keels or the lower all over, tipped with an awn 



0.5 to 1 mm. long, longest on the lower glume; flowering glume 7 to 8 mm. 



long, slightly scabrous toward the apex; callus barbate, 1 mm. long; awns 



nearly equal, scabrous, spreading, middle awn 18 to 22 mm. long, lateral awns 



16 to 20 mm. long. 

 Type specimen collected by Robert Combs and C. H. Baker, No. 1069, at ( Jrasmere, 



Florida, September 21, 1898. 

 A species with the habit and in part the appearance of A. palustris (Chapm. ) Vasey, 



but with a very distinct type of inflorescence. 



