390 rOLYGOXACE.E. (buckwheat family.) 



§ 3. Avictlaria. Floicers axillary, single or 2-3 together: stamens 8, rarely 

 fewer: stigmas 8, nearly 'sessile : ackenium 3-angled : cotyledons incumbent: albu- 

 min horny: sheaths scarious, 2 - 3-parted, lacerated: harts small. 



10. P. aviculare, L. Stem prostrate, diffuse, short-jointed ; leaves sessile 

 (£' long), oblong-Knew or lanceolate, obtuse, longer than the 3-clcft sheaths; 

 flowers clustered, Dearly sessile, greenish-white, longer than the dull achenium; 

 stamens mostly 5. — Waste places and along roads, common. — Var. eki:< i i m. 

 (P. irectuin, L.) Stem stouter, erect or ascending, leaves larger (1'- l£' long), 

 oblong, — With the preceding. — Var. littorale. (P. maritimum, L. P. 

 glaucutn, Nutt.) Stem -long (l°-2°), prostrate, rigid, short-jointed; leaves 

 small (4'*-6"), oblong-linear, glaucous; the uppermost imbricated and scarcely 

 longer than the more conspicuous silvery sheaths ; calyx reddish-white, shorter 

 than the smooth achenium. — Sea-coast sands, Georgia, and northward. 



11. P. tenue, Michx. Smooth; stem erect, branched, sharply angled, 

 slender; leaves scattered, linear, acute ; sheaths small, fringed ; flowers mostly 

 solitary, greenish-white; achenium smooth and shining. — Dry ro< ks in tho 

 upper districts. July - Sept. fjf) — Stem 6' - 8' high. Leaves 6" -12" long. 



§ 4. Tovakia. Flowers scattered in a long and slender spike: calyx 4-parted: 

 stamens 5, included: styles 2, exserted, persistent : achenium lenticular: cotyhdons 

 accumbt ut. 



12. P. Virginianum, L. Stem erect, smooth below ; the upper portion, 

 like the leaves and spikes, more or less hairy ; leaves large, ovate or ovate-lance- 

 olate, acute at each end ; sheaths cylindrical, hairy, fringed ; flowers greenish, 

 curved; styles at length hooked at the apex. — Dry rich soil, Florida, and 

 northward. Aug. and Sept. 1J. — Plant 2° - 4° high. Leaves 3' - 5' long, 

 l£'-2£' wide. . Spike G'- 12' long. 



§ 5. Echinocal'lon'. Flowers in terminal clusters: calyx 4 — 5-parted : stamens 

 6 or 8 : styles 2-3: achenium lenticular or 3-angled: cotyledons accumbent. — 

 Stems weak, branching, annul on the angles, petioles, §-c. with recurved prickles, 



13. P. arifolium, L. Leaves hastate, acuminate, membranaceous, mi- 

 nutely dotted and hairy, long-petioled, the lobes acute ; peduncles rather short, 

 bristly; flowers white, Bomewhat spiked; stamens 6; styles 2; achenium len- 

 ticular. — Pice fields and wet places, South Carolina, and northward. June- 

 Oct © — Stems 2° -3° long. Leaves 3'- 4' long. Calyx often 4-parted. 



1 I. P. sagittatum, L. Leaves small, sagittate, acute, short -pctioled, 

 smooth ; peduncles elongated, smooth ; flowers white, capitate ; stamens 8 ; 

 styles •'! ; achenium S-ahgled. — Wet places, Florida, and northward. Juno- 

 Oct. ® — Stem l°-3° long. Leaves l'-2' long. 



(j G. i'im\im\. Flowers in axillary dusters or racemes: calyx greenish white, 

 ^parted, the outer lobes keeled or winged on tl« back: stamens 8 : styles •'!, very 

 short: achenium Wangled: cotyledons accumbent. — Annuals, with twining sttws 

 .< cordati A oi 



15. P. Convolvulus, L. Stem roughish, prostrate or twining, or when 



small civet ; leaves long-petioli d, Bag ittale-cordate, acuminate, the lobes acute or 



