GRAMIKE&. 



315 



Order XCI. GR AMINES (Grass Family). 



Perennial herbs with fibrous roots, rarely arising from bulbs, 

 sometimes annual or biennial. Culms cylindrical, usually fistular, 

 closed at the nodes, sometimes solid. Leaves entire, usually 

 narrow, alternate, with the sheath split from one node down to the 

 next, usually with a membranous ligule between the base of the 

 leaf and sheath. Flowers in spikes, racemes, or panicles, usually 

 perfect, in I to many-flowered spikelets, composed of glume- 

 like bracts in 2 rows. Outer bracts (glumes) 2, rarely i, often 

 unequal ; the inner 2 immediately inclosing each flower (paletz), 

 alternate. Perianth none, or consisting of very small, membranous 

 scales (squamulce). Stamens 1-6, commonly 3, Anthers versatile. 

 Ovary i -celled. Styles 2. Stigmas 2, feathery. Fruit a caryopsis. 



i. Spikelets i-flowered, with 2 glumes and 2 paleae, or less. , 



* GLUMES ABSENT, OR BOTH VERY MINUTE. PALEAE 2. Leersia. 



* * SPIKELETS IN PANICLES, OFTEN CONTRACTED, AND APPARENTLY RACEMOSE. 

 + Palece awnless or with inconspicuous awns. 



Glumes equal, or the lower somewhat longer. Paleae thin, not coriaceous, ob- 

 tuse, upper smaller ; one often minute or wanting. Agrostis. 



Lower glume smaller, often minute, usually shorter. Paleae surrounded by 

 short hairs at base ; lower 3-nerved, usually mucronate. Stamens 3. Muhlen- 

 bergia. 



Spikelets with a rudimentary, plumose pedicel. Glumes mostly nearly equal, 

 longer than the flower. Paleae surrounded at base by a tuft of white bristles ; lower 

 paleae awnless, or with inconspicuous awn attached to the back. Stamens 3. Cala- 

 magrostis. 



Spikelets with 2 rudiments of abortive flowers, i on each side of the perfect 

 flower. Paleae shorter than the equal glumes. Phalaris. 



+ + Paletz with a conspicuous awn. 



Lower glume smaller than the upper, sometimes minute. Paleae 2, herbaceous. 

 Awn of the lower palea single, not jointed on its apex. Muklenbergia. 



Glumes not equal, often mucronate. Lower palea with 3 awns at tip, much larger 

 than the upper. A ristida. 



* * * FLOWERS ARRANGED IN SIMPLE OR NEARLY SIMPLE SPIKES. 

 t Spike terminal, 



Spike simple, dense, cylindrical. Glumes mucronate or awned. Paleae both 

 present, awnless. Phleum. 



Spikelets in threes at each joint of the rachis. Glumes side by side, mucronate, 

 awned. Lower palea awned at apex. Hordeum. 



t \ Spikes more than one. 



Spikelets loosely arranged in 2-4 rows, on one side of the flattened rachis. Spikes 

 few. Paspalum. 



Flowers oblong, crowded in clusters of 2-3, in i-sided, approximate, slender 

 cpikes. Panicum. 



