GRAMINEAE 11 



2. Philotria angustifolia Muhl. Si<ender Water- \^ eed. (Man. p. 

 60; I. F. f. 20J.) In shallow water, northeastern N. A. — Pennsylvania : 

 Bucks, Pt. Pleasant. 



2. VALLISNERIA L. 



1. Vallisneria spiralis L. Tape-GRAss. Eel-Grass. (Man. p. 60; 

 I. F.y. 20S.) In quiet waters, N. B. to Minn., Fla. and Tex. — Pennsyl- 

 vania: Northampton; Delaware; Chester; Lancaster; Dau- 

 phin ; Franklin ; Huntingdon ; Allegheny ; Erie. 



Orders. GRAMINALES. 



Leaves 2-ranked, their sheaths with ununited margins : stems mostly hollow : 

 fruit a caryopsis. Fam. i. Gramineae. 



Leaves 3-ranked, their sheaths with united margins : stems mostly solid : fruit 

 an achene. Fam. 2. Cyperaceae. 



Family i. GRAMINEAE Juss. Grass Family. 



I. Spikelets falling from the pedicel entire (see also nos. 25, 27, 33, and 41 



of section B), naked, or enclosed in bristles or a bur-like involucre, or im- 

 mersed in the internodes of a readily disarticulating rachis, i -flowered, or if 

 2-flowered the lower flower staminate ; no upper empty scales : rachilla 

 not extending beyond the uppermost scale. 

 Spikelets terete or somewhat dorsally compressed ; empty scales manifest : 

 hilum punctiform. 

 Flowering scale and palet hyaline, thin, much more delicate in structure 

 than the thick-membranous to coriaceous empty scales. 

 Spikelets unisexual, the pistillate borne in the lower, the staminate in 



the upper, part of the same spike. Tribe I. MAYDEAE. 

 Spikelets in pairs, one sessile, the other pedicellate, the former perfect, 

 the latter sometimes perfect, more commonly with a staminate flower, 

 often emptj' or reduced to one or two scales, or occasionally wanting. 



Tribe II. ANDROPOGONEAE. 

 Flowering scale, at least that of the perfect flower, similar in texture to 

 the empty scales, or frequently thicker and firmer, never hyaline and 

 thin. 

 Flowering scale and palet membranous. 



Tribe III. ZOYSIEAE. 

 Flowering scale and palet chartaceous, cartilaginous, or coriaceous, very 

 different in color and appearance from the other scales. 



Tribe IV. PANICEAE. 

 Spikelets much compressed laterally ; empty scales none or rudimentary : 

 hilum linear. Tribe V. ORYZEAE. 



II. Spikelets with the empty scales persistent, the rachilla hence articulated 

 above them (below them in nos. 25, 27, 33, and 41 and the spikelet fall- 

 ing entire), i-many-flowered : frequently the upper scales are empty: 

 rachilla often produced beyond the uppermost scale. 



A. Spikelets borne in open or spike-like panicles or racemes, usually upon 

 distinct and often long pedicels, 

 a. Spikelets i-flowered. 

 Empty scales 4 : palet i-nerved. Tribe VI. PHALARIDEAE. 



Empty scales 2 (rarely i) : palet 2-nerved. 



Tribe VII. AGROSTIDEAE. 



