390 POLiGONACE^. (buckwheat family.) 



§ 3. AvicnLAKiA. Flowers axillm-y, single or 2-3 together: stamens 8, rareli/ 

 fewer : stigmas 3, nearbj sessile : achenium 3-angled : cotyledons incumbent : albu- 

 men horny : sheaths scarious, 2 - 3-parted, lacerated : leaves small, 



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

 (J' long), oblong-linear or lanceolate, obtuse, longer than the 3-oleft sheaths ; 

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

 stamens mostly 5. — Waste places and along roads, common. — Var. erectum. 

 (P. erectum, L.) Stem stouter, erect or ascending, leaves larger {!'- 1^' long), 

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

 glaacum, Nutt.) Stem long (1°~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 rocks in the 

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



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

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

 acciunhent. 



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. IJ. — Plant 2° -4° high. Leaves 3' -5' long, 

 l^'-2j'wide. Spike 6'- 12' long. 



§ 5. EcHiNOC.vnLON. Flowers in terminal clusters: calyx i - 5-parted : stamens 

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

 Stems iveak, branching, armed on the angles, petioles, S^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, somewhat spiked ; stamens 6 ; styles 2 ; achenium len- 

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

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



14. P. sagittatum, L. Leaves small, sagittate, acute, short-petioled, 

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

 styles 3; achenium 3-angled. — Wet places, Florida, and northward. June- 

 Oct. ® — Stem 1 ° - 3° long. Leaves 1 ' - 2' long. 



5 6. TiNiARIA. Flowers in axillary clusters or racemes: calyx greenish white, 

 5-parted, the outer lobes keeled or winged on the back : stamens 8 : styles 3, very 

 short : achenium 3-angled : cotyledons accumbent. — Annuals, with twining stems 

 and cordate leaves. 



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

 small erect ; leaves long-petioled, sagittate-cordate, acuminate, the lobes acute or 



