68 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



1. Poa annua I,. Sp. PI. 68. 175:5. Annual butf.orass. 

 A low tufted, pale green annual with erect or ascending, somewhat flattened culms, 



5 to 30 cm. high, flat, thin, spreading leaves, and usually open, short-pyramidal pani- 

 cles 2 to 5 cm. long; spikelets 3 to 6-flowered, about 4 mm. long; glumes slightly 

 unequal, the second 3-nerved; lemmas obtuse, hairy on the nerves below and pilose 

 at the base, about 2 mm. long, distinctly 5-nerved. 



Fields and waste places, Aleutian Islands to southeastern Alaska, eastward to Lab- 

 rador and southward; also in Europe and Asia. 



2. Poa alpina L. Sp. PI. 67. 1753. Mountain bluegrass. 

 A densely cespitose, glabrous, erect perennial, 5 to 30 cm. high, with rather broad, 



flat, firm leaves and spreading, densely flowered, usually purplish, pyramidal panicles 

 3 to 9 cm. long; spikelets 5 to 6 mm. long, 3 to 6-flowered; glumes broad, aculeolate, 

 scabrous on the keels above, otherwise glabrous; lemmas about 4 mm. long, pilose on 

 the keel and nerves below, pubescent between the nerves near the base. 



Along cold mountain streams, open slopes, and canyons, Seward Peninsula to south- 

 eastern Alaska, eastward to Labrador, and southward in the mountains to Colorado; 

 also in Europe and Asia. 



2a. Poa alpina vivipara (Willd.) 



Poa vivipara Willd, Enum. PL 105. 1809. 



A form with many of the glumes developed into leaflets. Distinguished from Poa 

 stenantha vivipara by its very firm rigid leaves. 



Specimens examined: Hall Island, Trelease & Saunders 2964; St. Matthew Island, 

 Trelease <fc Saunders 2963, Coville & Kearney 2104; Kukak Bay, Coville. & Kearney 

 1500 bis; Popof Island, Kincaid in 1899; Yakutat Bay, Trelease & Saunders 2966, 

 2971; Hidden Glacier, Yakutat Bay, Coville tfc Kearney 972; Glacier Bay, Trelease & 

 Saunders 2965, Coville <fe Kearney 647; Juneau, Cooley in 1891. 



3. Poa arctica R. Br. Suppl. App. Parry's Voy. 288. 1824. 

 Poa williamsii Nash, Bull. N. Y. Bot. Gard. 2: 156. 1901. 



A slender, cespitose, glabrous, erect perennial 10 to 30 cm. high, with open, few- 

 flowered, purplish panicles and short, narrow leaves, those of the culm 2 to 3 cm. long; 

 panicles 3 to 6 cm. long, the glabrous branches mostly spreading, naked below, bear- 

 ing 2 or 3 spikelets toward the apex; spikelets ovate, 2 to 4-flowered, about 4 mm. 

 long; glumes subequal, slightly shorter than the lemmas, these silky-pubescent on 

 the keel and nerves below, webbed at the base, pubescent between the nerves toward 

 the base. 



Throughout Alaska and eastward to Labrador, south to British Columbia and (?) 

 Colorado; also in Siberia. 



This species is widely distributed in the arctic regions and has been confused with 

 Poa cenisia AIL, from which it differs in having the lemmas pubescent between the 

 nerves below; in P. eenlsia the lemma is pubescent only on the nerves. Our concep- 

 tion of P. arctica is based upon a portion of Robert Brown's type from Melville Island 

 (from British Museum), and from the grass described by Nash under the name of P. 

 williamsii, which is identical with Brown's specimen. 



4. Poa glacialis sp. no v. 



A densely cespitose, glabrous perennial 20 to 30 cm. high, with rather broad, thin, 

 flat leaves and open panicles of few, large, deep purple spikelets; sheaths overlapping; 

 ligule thin, hyaline, truncate, 2 mm. long; leaf blades glabrous throughout, ascend- 

 ing, pale green, 4 to 6 cm. long, 3 to 4 mm. wide, abruptly acute, those of the innova- 

 tions usually longer and narrower; panicles 5 to 9 cm. long, the flexuous branches 

 glabrous, naked below, bearing two or three spikelets above, the lower ones about 

 5 cm. long; spikelets about. 7 mm. long, 5-flowered, broadly lanceolate; glumes 

 unequal, broadly lanceolate, acute, the first 3 mm. long, the second 1 mm. longer, 



