TlllANDElA. DIGYNIA. 57 



S»ECiES. 1. P. setnceian. 2. debile. 3 ciUatifolUtm. 4. 

 dasiiphyllinn, Ki,. 5 prcecox. 6 Icevc 7 Floridaiuim. 6. pli- 

 catuhiin. 9.purpu7'ascens, r], \Q. distichum. 11. va^iiiat'im-— 

 §11. Spikes in racemes.— 12 membnmaceinn. 13- stolonife- 

 riim. In New-Jersey, Pursh. Near Xew Orleans abundant. 

 I Suspect these 2 last marked as --peoies, are varieties of 

 the same plant. This species, orig-inally discovered in 

 Peru, has been g-reatly recommended to agriculturists. 

 In warm, maritime situations, it continues growing^ and 

 flowering- throug-hout the year, and is ui.doubtedly pro- 

 ductive and important in south America; but in Kurope 

 it is entirely desu-oyed by the ea'licst frosts of the au- 

 tumn, being- quite a tropica! annual 



This genns, w.th the exceptKm of the above species, is 

 confined to the West I idies and the tropical portions of 

 the American continent; tliere is at the same lime, 1 spe- 

 cies in Japan, 2 in Inda, 1 -n Surinam (Africa), and ano- 

 ther in China The P. conjugatiim is common both to Ja- 

 maica and Surinam. There are also a few species in 

 Kew Holland. Europe produces no species of this ge- 

 nus. 



S5. ARISTIDA. Z. 



CaZia^ 2-Talved, 1 -flowered. Corolla 1-valved, 

 terminated by 3 awns. 



Culm paniculate; panicle sometimes contracted like a 

 dense spike, or elongated into a compound raceme, in 

 others spreading- or divaricate, in some species tricho- 

 tomous, in oth.ers dichotomous. Flowers commonly- 

 approximating by pairs; calix as in Avena and Siipa, 

 longer or shorter than the corolla. Corolla genei-ally de- 

 scribed as cons's'ing of a s'ngle glume; Mr. F.lliott de- 

 tects the rudiments of a minute inner glume in .?. spici- 

 formis and A lanosa- The corolla of all the species is 

 terminated by 3 awns, sometimes of very unequal length, 

 scabrous or plumose, inclined in various directions, the 

 central awn often horizontal, sometimes all equal and 

 then divaricate, the awns very rarely contorted. 



Species. 1. A. spiciformis. El. 2. stricta. 3. Imioso, El. 

 4. gracilis, E. 5. oliguntha. 6. dichotoniUr (the larger con- 

 torted awn of this species is hygrometric.) 7. pallens, (in 

 depressed situations, near Fort Mandanon the Missouri.) 



8. *tuberculosa Culm rigidly erect, dichotomous, with 

 tumid articulations and small tubercles or callosities in 

 the axillae of all the branches; panicle rigid, rather short, 

 ramuli approximating towards the summit of the culm. 



