58 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



9. PODAGROSTIS (Griseb.). 



Agrostis section Podagrostis Griseb. in Ledeb. Fl. Ross. 4: 436. 1853. 



Spikelets 1-flowered, rachilla prolonged behind the palea into a minutely pubescent 

 rudiment which is a little less than half the length of the palea; callus naked; glumes 

 2, equal, as long as the floret; lemma usually with a minute awn which is attached 

 near the apex; palea nearly equaling the lemma, less firm in texture and nearly 

 hyaline. 



A genus intermediate between Agrostis and Calamagrostis, differing from the former 

 in having the glumes and lemma equal and the rachilla prolonged; from the latter in 

 its minute terminal awn, equal glumes and lemma, and the absence of callus hairs. 



1. Podagrostis aequivalvis (Trin.) 



Agrostis canina aequivalvis Trin. in Bong. Mem. Acad. St. Petersb. VI. Math. Phys. 

 Nat. 2: 171. 1832. 



A slender, erect, glabrous perennial 15 to 50 cm. high, with linear, plane leaves and 

 exserted open, few-flowered, purplish panicles 5 to 10 cm. long; spikelets 3 to 3.5 mm. 

 long, glabrous, ovate, acute; glumes equal; lemma equaling the glumes, acute, 

 glabrous, sometimes with a very short awn near the apex; callus with a few short hairs; 

 prolongation of the rachilla pilose, about two-thirds as long as the lemma. 



In marshes and swamps, Unalaska to Yakutat Bay and southeastern Alaska, thence 

 southward to the mountains of Oregon. 



Alaska specimens: Sitka, Mertens (specimen from the type collection from Herb. 

 Acad. St. Petersb.), Wright 1579, Piper 4620; Helm Bay, Cleveland Peninsula, Fletl 

 2015; Yes Bay, Howell 1712, Gorman 92; Latouche, Piper 4621. 



A species readily recognized by its slender habit, by its lemma equaling the glabrous 

 glumes, and by the pilose prolongation of the rachilla, in which character it approaches 

 the genus Calamagrostis. 



A specimen from Unalaska with the lemma one-third shorter than the glumes, was 

 called Agrostis aequivalvis obliqua by Grisebach a but we have seen no specimens 

 representing this variety. 



10. CALAMAGROSTIS Adans. 



Calamagrostis Adans. Fam. PI. 2: 31. 1763. 



Spikelets 1-flowered; rachilla produced above the floret into a short, usually hairy 

 pedicel or bristle; glumes subequal, awnless and usually exceeding the lemma, this 

 surrounded at the base with copious hairs and awned on the back, usually from below 

 the middle. Tall, often reed-like, perennial grasses with small spikelets in many- 

 flowered terminal panicles. 



Awn strongly geniculate, exserted ; callus hairs shorter than the , 



lemma. 

 Low grasses, not exceeding 30 cm. in height; leaves glabrous. 



Panicle densely flowered, 2 to 3 cm. long 2. C. arctira. 



Panicle open, pyramidal, 4 to 9 cm. long 1. C. desehampsioides . 



Tall stout grasses 30 to 140 cm. high; leaves scabrous. 



Plant 60 cm, high or less; leaf blades involute or plane, 



5 mm. wide or less; awn long-exserted 3. C. purpurascens. 



Plant robust, exceeding 60 cm. in height, leaf blades 



6 to 12 mm. wide; awn but slightly exserted 4. C. aleutica. 



Awn straight or nearly so, not exserted; callus Imirs mostly 



equaling the lemma. 



a Ledeb. Fl. Ross. 4: 436. 1853. 



