?20 



GEAMINEAE (GRASS FAMILY) 



1. Z. palustris L. (Indian Rice, "Water Oats.) Annaal ; culms 2-3 m. 

 bigh ; leaves flat, 5-10 dm. long, 1.5-4c m. wide. (Z. aquatica of auth. not L.) — 

 Swampy borders of streams and in shallow water; common, 

 especially northwestw. July, Aug. (Asia.) Fig. 73. 



2. Z. aquitica L. Culms about 1 m. high ; leaves nar- 

 rower (less than 1 cm. wide) ; pistillate portion of panicle 

 more appressed. — Me. to Minn., and northw. 



17. ZIZANI6pSIS Doll & Asoh. 



Spikelets unisexual, the pistillate above, the staminate below 



on each branch of the panicle, much alike in appearance, 



laterally compressed ; glumes subequal, membranaceous, the 



first glume of the pistillate spikelet with a short terminal awn, 



the lemma acute, palea none ; glumes and lemma of staminate 



spikelet acute, nerveless, palea none ; stamens 6 ; grain ovoid, 



with a chartaceous easily separable pericarp, loosely inclosed 



in the glumes.- — A tall aquatic grass with long leaves and 



long narrow terminal panicles. (Name from Zizania and 



Si//!!, appearance, from likeness to the preceding genus.) 



1. Z. miliUcea (Miohx.) Doll & Asch. Perennial by a creeping rootstock; 



culms 1-4 111. high, geniculate at the lower nodes; leaves flat, 3-10 dm. long, 



1-3 cm. wide. {Zizania Michx.) — Swamps, Va., O., and southw. May. 



73. Z. aquatica x 1. 

 rf spikelet. 

 $ spikelet. 

 Pistil with scales. 



18. LE^RSIA Sw. Cnx-GKASS. White Grass 



Spikelets 1-flowered, flattened laterally, perfect, but those in the open panicles 

 usually sterile, those inclosed in the sheaths cleistogamous and fruitful ; glumes 

 none, lemma boatshaped, somewhat indurated, awnless, 

 clasping the palea by a pair of strong marginal nerves ; palea 

 of like texture, much narrower, 1-nerved; stamens 1-6. — 

 Perennials of moist ground, with rough leaves and short 

 racemes of imbricated spikelets arranged in open panicles. 

 (Named after Johann Daniel Leers, a German botanist of 

 the 18th century.) Hoiialocenchrus Mieg. 



* Spikelets narrowly oblong, rather loosely crowded. 



1. L. virglnica Willd. (White Grass.) Culms weak, 

 branched, ascending, with clustered scaly rootstocks ; panicle 

 simple, the slender branches stiiHy spread- 

 ing ; spikelets 2.5-3 mm. long, closely ap- 

 pressed ; lemma hispid on the keel ; stamens 

 2. — Wet woods. Me. to Ont., and southw. 

 Aug. Fig. 74. 



2. L. oryzoides (L.) Sw. (Rice Cut-grass.) Culms rather 

 stout, branched, ascending from a dectimhent base with (^lender 

 creeping rootstocks; leaves very rough; panicle diffusely 

 branched, lax ; spikelets 4-5 mm! long ; lemma hispid, strongly 

 bristly ciliate on the keel. — Swamps or stream borders, ditches, 

 etc., Nfd. to Ont., and southw. Aug., Sept. (R. A., Eurasia.) 

 Fig. 75. 



74. L. virffinica. 

 A bit of Inflorescence 



x3. 

 Spikelet X 5. 



VS. L. oryzoides. 

 Inflorescence x Vb- 

 A bit of same x %. 

 Open spikelet x 2. 



* Spikelets broadly oval, imbricntehj covering each other. 



ciliate. 



3. L. lenticul^ris Michx. (Catcii-fly Grass.) Culms 

 nearly simple, erect or decumbent at base, with scaly root- 

 stocks ; sheaths and blades sometimes nearly smooth ; panicle 

 nearly simple ; spikelets very flat, 5 mm. long, strongly bristly- 

 liOW grounds, Va, to Minn., and southw. 



