156 



POACEAE 



29. GASTRIDIUM Beauv. Ess. Agrost. 21. pi 6. f. 6. 1812. 



Spikelets 1-flowered, the rachilla disarticulating above the glumes, prolonged behind the 

 palea as a minute bristle; glumes unequal, somewhat enlarged or swollen at the base; lemma 

 much shorter than the glumes, hyaline, broad, truncate, awned or awnless ; palea about as 

 long as the lemma. Annual grasses with flat blades and pale shining spikelike panicles. 

 [Greek, belly, referring to the saccate glumes.] 



Species 2, in the ^Mediterranean region, one introduced into the United States. Type species, ]\Iilinm 

 lendigernm L. 



1. Gastridium ventricosum (Gouan) 

 Schinz & Thell. 



Nit-grass. 



Fig. 348. 



Agrostis ventricosa Gouan, Hort. Monsp. 39. p!. 1. f. 2. 1762. 



Milium lendigerum L. Sp. PI. ed. 2. 91. 1762. 



Gastridium australe Beauv. Ess. Agrost. 21, 164. 1812. 



Gastridium lendigerum Desv. Obs. Angers. 48. 1918. 



Gastridium ventricosum Schinz & Thell. Mitt. Bot. Mus. Uniy 

 Zurich 58: 59. 1913. 



Culms about 30 cm. tall, smooth ; panicle 5-8 cm. 

 long, dense and spikelike ; glumes 3 mm. long, grad- 

 ually narrowed into an awn-point ; lemma much 

 shorter than the glumes, globular, pubescent, the awn 

 5 mm. long, geniculate. 



Open ground and waste places. Transition Zone; mostly in 

 the Coast Ranges, at moderate altitudes. Oregon to California 

 and Texas; introduced from Europe. May-July. Type lo- 

 cality, European. 



30. CALAMAGROSTIS Adans. Fam. PI. 2: 31. 530. 1763. 



Spikelets 1 -flowered, tlie rachilla disarticulating above the glumes, usually prolonged 

 behind the palea as a short usually hairy bristle ; glumes about equal, acute or acuminate ; 

 lemma shorter than the glumes, usually more delicate than these, glabrous in our native 

 species, surrounded at base with a tuft of hairs, these usually copious, often as long as the 

 lemma, awned from the back, usually below the middle, the awn delicate and straight, or 

 stouter and exserted, bent and soinctimes twisted ; palea shorter than the lemma. Perennial, 

 usually moderately tall or robust grasses with small spikelets in open or usually narrow 

 sometimes spikelike panicles. [Greek, reed-agrostis.] 



Species about 100 in the cool and temperate regions of both hemispheres. Type species, Ariindo calama- 

 grostis L. 



Awn longer than the glumes, geniculate. 



Panicle open, the branches spreading, naked below. 



Blades scattered, broad, flat; plant mostly over 1 meter tall. 



Blades mostly basal, narrow, mostly not over 2 mm. wide, often involute. 



Awn about 1 cm. long, much longer than the glumes; blades nearly or quite as long as the 



flowering culms. 2. C. howellii. 



Awn only a little e.xceeding the glumes; blades much shorter than the culms, capillary. 



3. C. breweri. 

 Panicle compact, the branches appressed, floriferous from the base. 

 ' Blades scattered, broad, flat, 6-10 mm. wide. 4. C. tweedyi. 



Blades mostly basal, firm, narrow, becoming involute. 



Glumes about 1 cm. long, gradually long-acuminate; awn about 1 cm. long above the bend. 



5. C. foliosa. 

 Glumes about 5 mm. long, abruptly acute or acuminate; awn usually less than 5 mm. above the bend. 

 Marcescent lower sheaths prominent, extending up the culm for several centimeters; panicle 

 compact. 6. C". purpurascens. 



Marcescent sheaths inconspicuous; panicle rather loose, interrupted below. 



7. C. 7'aseyi. 

 Awn included or scarcely longer than the glumes, straight or geniculate. 



Awn geniculate, protruding sidewise from the glumes; callus hairs sparse, shorter than the lemma. 

 Sheaths glabrous on the collar. 



Panicle loose, the branches spreading or ascending; plants tall, in large bunches; blades as much 



1. C. bolanderi. 



as 1 cm. wide. 

 Panicle compact. 



Culms stout, mostly over 1 meter tall. 

 Culms slender, mostly less than 1 meter tall. 

 Sheaths pubescent on the collar. 

 Awn straight, included; callus hairs usually not much shorter than the glumes. 

 Panicle rather loose and open. 



Callus hairs about half as long as the lemma. 

 Callus hairs about as long as the lemma. 

 Spikelets about 2 mm. long. 

 Spikelets 3-5 mm. long. 

 Panicle contracted or spikelike. 



Blades short, as much as 5 mm. wide, nearly smooth. 

 Blades elongate, firm and rather rigid, scabrous. 



8. C. niitkaensis. 



9. C. densa. 



10. C. koelerioides. 



11. C. rubescens. 



12. C. calif omica. 



13. C. macouniana. 



14. C. canadensis. 



15. C. crassighDtiis. 



16. C. inexpansa. 



