46 



POACEAE 



2. Axis of spikelet jointed above the empty scales 



a. Flowering scale with more or less elongated awn 



(1) Awn short, less than 12 mm. long, not twisted 



(a) Awn about 10 mm. long, spikelets stalked, in a panicle Oryzopsis 



(b) Awn 1-5 mm. long, spikelets in a dense spike Alopecurus 



(2) Awn long, twisted, bent at the middle Stipa 



b. Flowering scale awnless 



(1) Spikelets in dense narrow panicles, 1-flowered Phalaris 



(2) Spikelets in loose panicles 



(a) Spikelets 3-flowered, the two lower staminate ; plants fragrant Hierochloe 



(b) Spikelets 1-flowered Milium 

 II. Spikelets with 2-many perfect flowers 



1. Flowering scale 1-3-nerved 



a. Spikelets 2-flowered, second empty scale broader than the flowering 



scale Sphcnopholis 



b. Spikelet 2-7-flowered, second empty scale not broader than the 



flowering scale Koeleria 



2. Flowering scale 5-many-nerved 



a. Flowering scale more or less strongly compressed and keeled, 



mostly webby at the base Poa 



b. Flowering scale rounded on the back, at least below, not webby 



(1) Spikelets solitary at each node 



(a) Stigmas at the apex of the ovary Fcstuca 



(b) Stisrmas below the apex of the ovary Bromus 



(2) Spikelets in pairs at the nodes AsprcUa 



Plate 20: A. Panicum, 1. part of panicle, 2. spikelet; B. Ory/.opsis asperifolia, 1, raceme, 2, 

 spikelet : C. Alopecurus pratensis, 1, spike, 2, spikelet ; 1). Stipa spartea. 1, spikelets, 2, 

 grain; E, Phalaris arundinacea, 1, part of panicle, 2, spikelet; F, Hierochloe odorata. 1. 

 panicle, 2, spikelet; G, Milium effusum, 1, part of panicle. 2. spikelet; H, Spenopholis 

 obtusata, 1, panicle, 2, spikelet; I, Koeleria cristata, 1, panicle, 2, spikelet; J, Poa pratensis, 

 1, part of panicle, 2, spikelet; K. Festuca octoflora, 1. spike, 2, spikelet; L, Bromus; M, 

 Asprella hystrix, 1. spike, 2, spikelet. 



Panicum — Panic Grass 



( L. panicum, panic grass) 

 PI. 20, fig. A : 1, 2 

 Annual or perennial grasses with small, 1 or 2-flowered spikelets, mostly in paniculate inflo- 

 rescence^; flowering scales generally firm and shiny. Many species, difficult of determination. 



( )ryzopsis — Mountain Rice 



(Gr. oryza, rice, opsis, look) 

 PI. 20, fig. B : 1, 2 

 Leaves crowded at the base, spikelets 6-8 mm. long 



Alopecurus — Foxtail ( rrass 



PI. 20, fig. C : 1, 2 

 Spikelets about 5 mm. long, in a dense spike-like panicle 



(). asperifolia 



. I. pratensis 



