(GRASS FAMILY.) 645 



2. P. Walterianum, Schultes. Perennial; leaves linear; short; spikes 

 3-7, the lowest partly included in the sheath of the uppermost leaf, the rhachis 

 blunt; spikelets glabrous. (P. vaginatum, Ell.) Low or wet grounds, New 

 Jersey (Cape May, Nuttall), Delaware (Tatnall, Canby), and southward. 



* * Spikes with a narrow wingless rhachis : perennials, or mostly so. 

 H- Spikelets very obtuse, orbicular : spikes one terminal and often 1-5 lateral. 



3. P. setaceum, Michx. Culm ascending or decumbent (1- 2 long), 

 slender; leaves (2" wide, flat) and sheaths clothed with soft spreading hairs; 

 spikes very slender (2' -4' long), smooth, mostly solitary on a long peduncle, and 

 usually one from the sheaths of each of the upper leaves on short peduncles or included ; 

 spikelets (%" wide) narrowly 2-rowed. (Also P. decile and P. ciliatifolium, Michx.) 

 Sandy fields : common from E. Mass, to Illinois, southward. Aug. 



4. P. laeve, Michx. Culm upright, rather stout (1- 5 high) ; the pretty 

 large and long leaves with their flattened sheaths smooth or somewhat hairy ; 

 spikes 2-6, the lateral ones somewhat approximated near the summit of an elon- 

 gated naked peduncle, spreading (2' -4' long), smooth, except a bearded tuft at 

 their base; spikelets broadly 2-rowed (over 1" wide). Moist soil, S. New Eng- 

 land to Kentucky, and southward. Aug. Either glabrous or sometimes the 

 lower sheaths, &c. very hairy. As here received this perhaps comprises two or 

 more species. 



- *- Spikelets acute : spikes always a pair at the summit of the naked peduncle. 



5. P. distichum, L. (JOINT-GRASS.) Nearly glabrous, rather glaucous ; 

 culms ascending (about 1 high) from a long creeping base; leaves linear-lan- 

 ceolate (2' -3' long); spikes short and closely-flowered (9" -2' long), one short- 

 pedunded, the other sessile ; rhachis flat on the back ; spikelets ovate, slightly pointed 

 (barely 1^" long). Wet fields, Virginia and southward. July -Sept. 



6. P. Digitaria, Poir. Culms ascending (l-2high) from a creeping 

 base ; leaves lanceolate (3' 6' long, 4" 6" wide) ; spikes sender, rather sparsely 

 flowered (l'-4' long), both sessile at the apex of the slender peduncle; spikelets 

 ovate-lanceolate (2" long). (Miliuin paspalodes, Ell.) Virginia and southward. 



60. PANICUM, L.. PANIC-GRASS. (PI. 13.) 



Spikelets panicled, racemed, or sometimes spiked, not involucrate, l- 2-flow- 

 ered. Glumes 2, but the lower one usually short or minute (rarely even want- 

 ing), membranaceo-herbaceous ; the upper as long as the fertile flower. Lower 

 flower either neutral or staminate, of one palet which closely resembles the upper 

 glume, and sometimes with a second thin one. Upper flower perfect, closed, 

 coriaceous or cartilaginous, usually flattish parallel with the glumes, awnless 

 (except in 3), enclosing the free and grooveless grain. Stamens 3. Stigmas 

 plumose, usually purple. (An ancient Latin name of the Italian Millet, P. 

 Italicum (now Setaria Italica), thought to come frompanis, bread ; some species 

 furnishing a kind of bread-corn.) 



1. DIGIT ARIA, Scop. Spikelets crowded 2-3 together in simple and mostly 

 l-sided clustered spikes or spike-like racemes, wholly awnless and pointless : lower 

 flower neutral, of a single palet: lower glume minute, sometimes obsolete or want- 

 ing : root annual : plant oflen purplish. 



