586 OEDER CXLII. GRAMINACE^. 



Genus XXIII. —SPARTI'NA. 



(From sjmriine, a cord, from the toughness of the leaves.) 



Flowers in 1 -sided spikes, imbricate, in 2 rows. Glumes 2, 

 unequal, keeled. Paleoe 2, unequal, without awns. 



1. S. jun'cea, (Willd.) >S<(??n glabrous, columnar, ieaves linear, con- 

 volute when old ; sheaths glabrous, ciliate at the throat ; spikes few, 

 pedunculate ; exterior glume small, the interior one long, keeled ; ex- 

 terior palea shortest, the interior compressed, as long as the glume. — ?f . 

 Through the summer. Sea-coast. 2 — 3 feet. 



2. S. POLYSTA'cin'A. Stem glabrous, columnar. Leaves broad, very- 

 long, scabrous on the upper surface ; sheath longer than the joints, 

 with the throat hairy ; spikes numerous, 10 — 12, expanding, alternate. 

 — If. Sept, On the sea-coast. 3 — 10 feet. 



3. S. gla'bra, (Muhl.) {S. Icevigata, Link.) Stem glabrous, fistular. 

 Leaves long, glabrous, concave ; spikes erect, appressed, 5 — 8. Glumes 

 and paleas ciliate on the keels. — If. August—Sept. On the sea-coast. 

 2—4 feet. 



Genus XXIV.— GYMIS^OPO'GOX. Beauv. 



(From gumnos, naked, onApogon, a beard.) 



Glumes 2, carinate, nearly equal, longer than the floret. 

 Palece shorter than the glumes, equal ; the exterior one 3- 

 nerved, terminated by a straight awn. Spike pauicled. 



1, G. RACEMo'sus, (Beauv.) Stem erect and decumbent, glabrous, 

 short joints. Leaves distichous, cordate, lanceolate, nerved, short, gla- 

 brous ; sheaths hairy at the throat. Panicle terminal, expanding, some- 

 what verticillate. — U- Sept. — Oct. Dry soils. 1 — 2 feet. 



Tribe VII.— AVENA'CEtE. 



Spikelets 2 — many-flowered, panic! ed ; the lower palea bear- 

 ing a twisted or bent awn on the back. 



Genus XXV.— AI'RA. L. [Hair-grass.) 

 " (An ancient Greek name for Darnel.) 



Glumes 2, 2 — 3-flowered. Palem 2, equal, inclosing the 

 seed, exterior one usually awned. Panicle comjjound. 



1. A. FLExuo'sA, (L.) Stem erect, terete, glabrous. Leaves setaceous. 

 Panicle diffuse, with the branches somewhat verticillate. Glumes un- 

 equal. Palece equal, the exterior one yjubescent at the base, bearing 

 an awn at the base. — %. August — Sept. Shady woods. 1 — 2 feet. 



2. A. capilla'cea, (L.) Ste7n erect, sma'l. Leaves short, glabrous, 

 narrow. Flowers in capillary panicles, diffuse, large for the size of the 

 plant. Glumes acute, with the keel rough. Palece unawned, larger 

 than the glumes. — ©. July — Aug. Sandy soils. 8 — 10 inches, 



3. A. triflo'ra, (Ell.) [Graphephorimi Elliottii, Kunth.) Stem erecti 

 glabrous, slender. Leaves short, flat, scabrous on the under surface 



