152 - i'UACEAl-; 



raanv-flowercd, ovate to oval when mature, 12-2") nun. long, the flowering scales 8-10 mm. 

 long and hispidulons on the keel. 



In sands along the seacoast, Virginia to Florida and Texas. Also in the ^Vest Indies and South 

 America. Fall. Sea Oats. 



109. DISTICHLIS Raf. 



Perennial dioecious grasses, with rigid creeping or decumbent stems concealed by the 

 overlapping leaf-sheaths, stiff flat or convolute leaf-blades, and contracted panicles. 

 Spikelets many-flowered, unisexnal, more nnmerous in the staminate tlian in the pistillate 

 panicles, the rachilla continuous in the staminate, articulated in the i)istillate spikelets. 

 Scales many, acute, keeled, the 2 lower empty, narrow, the flowering scales longer and 

 broader, firm-membranons or nearly coriaceous ; jialet compressed, 2-keeIed, the keels 

 sometimes narrowly winged. Stamens 3. Styles thickened at the contiguous but distinct 

 bases, moderately long. Stigmas plumose. 



1. Distichlis spicata ( L. ) Greene. Stems 1-6 dm. long, erect, or often decumbent 

 at the base, from a long rootstock : leaf-sheaths overlapping and often crowded ; blades 

 1-15 cm. long, 2-4 mm. wide, flat or involute : panicle dense and spike-like, 2-6 cm. long, 

 its branches erect : spikelets 8-lS mm. long, 6-16-flowered, pale green, the flowering scales 

 3-5 mm. long, acute or acuminate. \_D. maritlma Kaf. ] 



On salt meadows along the Atlantic coast from Maine to Florida and Texas, on the Pacific Coast, 

 and in saline soil throughout the interior. Summer. Spike (;kass. 



110. DACTYLIS L. 



Perennial usually tall grasses, with flat leaf-blades and open or contracted panicles. 

 Spikelets in head-like clusters which are unilaterally arranged and crowded at the ends of 

 the branches, 3-5-flowered, the flowers perfect or tlie npper ones staminate. Scales 5-7, 

 keeled, the 2 lower empty, unefjual, mucronate, the second the larger, the flowering scales 

 larger, more rigid, tlie keel ciliate and excurrent as a niucro or short awn ; palet nearly 

 as long as the scale, 2-keeled. Stamens 3. Styles distinct. Stigmas plumose. 



1. DactylLs glomerata L. Stems 6-12 dm. tall, tufted, erect: leaf-sheaths smooth 

 or rough ; blades 7-23 cm. long, 2-6 mm. wide, flat, rough : panicle 7-20 cm. long, its 

 branches spreading or ascending in flower, erect in fruit : spikelets in dense capitate clusters, 

 3-5-flowered, the flowering scales 4-6 mm. long, rough, pointed or short-awned, ciliate on 

 the keel. 



In fields, meadows and waste places, New Brunswick to Manitoba, Georgia and Colorado. Natu" 

 ralized from Europe. Summer. Okchard Grass. 



111. POA L. 



Annual or perennial grasses, rarely dioecious, with flat leaf-blades and open sometimes 

 contracted panicles, the branches often drooping. Spikelets 2-6-flowered, the flowers per- 

 fect, or rarely nnisexual, the glabrous or rarelv somewhat pilose rachilla articulated between 

 the flowers. Scales 4-8, membranous, keeled, acute or obtuse, awnless, the 2 lower empty, 

 persistent, the flowering scales usually longer, frequently pubescent on the callus and the 

 midnerve and marginal nerves, the hairs often long and curled ; palet shorter than the 

 scale, 2-nerved or 2-keeled. Stamens 3. Styles short, distinct. Stigmas plumose. Meadow 

 Grass. Spear Grass. Blue Grass. 



Annuals or biennials : stems densely tufted, low, usually less than 3 dm. long. 



Flowering scales distinctly .5-nerved, not webby at the base. 1. P. annua. 



Flowering scales ill-nerved or sometimes with a pair of obscure additional 



nerves, webby at the base. -• P. Cliapmaniana. 



Perennials : stems usually exceeding 3 dm. in height. 

 A. Plants green, with no long rootstocks. 



a. Flowering scales with lotig crimped hairs at the base. 

 Flowering scales with only the midnerve pubescent. 



Flowering scales 2.5 mm. long, the midnerve sparsely pubescent : plant 



yellowish green. 3. P. tririalis. 



Flowering scales 3.5 mm. long, the midnerve densely pubescent : plant 



green. 4. P. alsodes. 



Flowering scales with the midnerve and lateral nerves pubescent. 

 * Panicle open, its branches spreading : spikelets not crowded. 



Midnerve of the flowering scale pubescent only below the middle. 

 Flowering scales about 3 mm. long : basal leaves usually rela- 

 tively short. 5. P. pratensis. 

 Flowering scales 4-5 mm. long: basal leaves verj' long, often 



equalling the stem in length or nearly as long. 6. P. hrevifoUa. 



