Piper— Andropogon halepensis and Andropogon sorghum. 41 



7 mm. long; awn 13 mm. long; sterile very narrowly lanceolate, and 

 without trace of stamens. 



Hackel refers to aethiopicus, a specimen collected in Darfur by Dr. 

 Pfund. This specimen is a panicle only with broadly lanceolate spikelets 

 hairy only near the margin, shiny on the back and at maturity black. 

 Awns 12 to 15 mm. long. It seems impossible to include it in cordofanus, 

 but it is more nearly allied there than to other forms. It may be a 

 cultivated plant or a hybrid with such. 



Still more doubtful is a specimen from Damaraland collected by 

 Marloth near the hot springs called Barmen. This plant has the same 

 pale herbage as cordofanus, but the leaves are narrower and longer and 

 the culms apparently more slender. The spikelets are narrower than 

 those of cordofanus, dark purple covered with a purplish pubescence, 

 except a small area on the back. x\wns 16 mm. long. Additional 

 material will probably show this to be distinct. 



Andropogon sorghum hewisoni n. subsp. 



Culms stout, several to many from the same roots, erect, 1-3 cm. in 

 diameter, 3-3.5 meters tall, somewhat waxy coated; nodes 13 to 19; leaf 

 blades 70-100 cm. long, flat, 4 to 8 cm. broad, the sheaths mostly longer 

 than the internodes; panicle barely exserted from the uppermost sheath, 

 very compact, somewhat fusiform, thickest in the middle, 10-15 cm. 

 long, 3-4 cm. thick, the longest branches about one-third as long as the 

 panicle; spikelets moderately persistent ; lower glume of fertile spikelet 

 broadly ovate or oval, 6.5 mm. long, 3 mm. broad, 9-11-nerved, densely 

 covered with white hairs, green except the chestnut-red base; awns 11 

 mm. long, smooth to the elbow, scabrous above; lateral spikelets nar- 

 rowly lanceolate, hairy, without stamens; caryopsis brownish-yellow, 

 obovoid, compressed, 3.5 mm. long. 



Grown in the greenhouse from seed collected by R. Hewison, Esq., in 

 Sennaar Province, Sudan, "obtained from wild plants." 



At Arlington Farm, Virginia, the plants grew to a height of 2 to 2% 

 meters but did not bloom by the time of killing frosts. It is therefore 

 decidedly a long season plant. 



This subspecies strongly suggests cordofanus but the heads are much 

 more dense, the awns smaller and the lateral spikelets without stamens. 

 It is even more closely allied to the specimen collected by Brown in Sudan 

 referred to under cordofanus but that has loose panicles, and spikelets that 

 drop very readily. The dense heads suggest the possibility of its being a 

 cross with a cultivated variety of durra, but it does not seem that this is 

 probable. 



Hewisoni may be the wild original of the durras as the pubescence in 

 the spikelets suggests. This origin would be consistent with the restric- 

 tion of the true durras in Africa to Egypt and Sudan and with their 

 absence from other parts of that continent. 



Andropogon sorghum niloticus Stapf in herb. n. subsp. 

 Culms tall, stout, 4 mm. thick at base of panicle; leaf blades fiat, the 



