TRIANDRIA. DIOYNIA. 6'1 



frequently sheathed by c}mbif()rm acute or acuminated 

 leaves, in some species so closely as not to admit the ex- 

 pans on of the spikes; flowers alternate and sessile, with 

 lateral abortive pedicellae florets, someiimes mere bar- 

 ren pedicells, arising- near their base. In the American 

 species, the involucrate villus is often short, sometimes 

 inconspicuous- 



Species. 1. ^1. wttans. 2. avennceum. 3. ciliaUim, El. 

 A. melanocarpnSy t'-L. 5. scoparium. &. macroumm. 7.terna' 

 riiiin 8. virghiicum 9. bicorne. 10. argente'cm^ Eu. 11. 

 dhsitifioriim 12. vaginatum, El. 13. tetrastachyum^ El. 

 \4:. fnrcatnm. 



In India there are 11 species of this g-enus, 2 of which, 

 the A- J\'ar(kis and Jl. mnricatum^ are every where culti- 

 vated for their aroma* ic odour. There are also 3 species 

 in Japan, 5 in the sojirh of Europe, most o/' which aie also 

 indi.e^enous to Harbaiy, 1 spcc;ts pr^culiarto that country, 

 and 1 at the (Jape of Good Hope, 2 in the West India-^ 

 islands, and now 14 species enumerated in the United 

 States, of wh'.ch, several are also com uon to the tropical 

 reg'icns of the American continent. Excepting- the con- 

 tinent of India, there appears not to exist a sii'^gle genu- 

 ine species of Andropogon, wilhin the southern hemis- 

 phere. 



§ Ti. Calices ^-flow2red, dispersed. 



89. TRISETUM. Persooiu (Tliree-awned Oat- 

 grass.) 



Calix 2 to 3-flowered, acuminate and cari- 

 nate. Corolla, (outer valve) terminated by 2 

 shorter, almost tooth like awns (or the apex of 

 the .^lume setareously hi lid,) and 1 longer 

 straight dorsal awn, not contorted. 



Sjjecies of Ave n a of other authors, distinguished chief- 

 ly by a deeply elf ft acuminate and carinate dorsal valve, 

 a central struicfht awn, wiih compressed pale coloured 

 spikelets, and flosculi which are generally smooth. 



Species. 1 T pratense, {Avena favescens, L.) The rest 

 of this genus is chiefly confined to the ijouth of Europe, 

 Barbary, and the Cape of Good Hope. 



90. AIRA. Z. (Hair-grass.) 



Calix shining, 2-valved, 2 flowered. Corolla, 

 awnlcs.s, or awned from the base, 2-vaIvetU 



G 



