390 roLiGoxACE^E. (buckwheat family.) 



§ 3. Avicui.AKiA. Flowers axillary, single or 2-3 together: stamens 8, rarehj 

 fewer: stigmas 3, nearly sessile: achenium 3-angled : cotyledons imiumbent : albu- 

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



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

 {^' long), oblong-linear or lanceolate, obtuse, longer than the 3-ck'ft sheaths ; 

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

 stamens tnostly 5. — Waste places and along roads, common. — Var. erkctcm. 

 (P. crectum, L.) Stem stouter, erect or ascending, Ic.ives larger (1'- 1|^' long), 

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

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

 small (4"-G"), 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 angleil, 

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

 solitary-, greenish-white ; achenium smooth and shining. — Diy rocks in the 

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



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

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

 accumhent. 



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 ^ept. 1]. — Plant 2° - 4° high. Leaves 3' - 5' long, 

 1 i' - 2i' wide. Spike 6' - 1 2' long. 



§ 5. EcHiNOCiVL'LOK. Flowers in terminal clusters: calyx 4 - 5-parted : stametis 

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

 Stems weak, branching, aimed on the angles, petioles, Sfc. 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 wliite, 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. 



§ 6. TiNiARiA. Flowers in axillary clusters or racemes: calyx greenish white, 



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



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



and cordate leaves. 



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



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



