208 POLYGONACEAE 
smaller more gradually narrowed fruit. Sandy shores, Maine and north- 
ward. Aug.-Sept. 
19. P. erectum, L. (Fig. 5, pl. 34.) Erect Knotweep. Plant 
4 to 2 ft. high. Leaves oval or oblong, apex acute or somewhat obtuse; 
joints large with 1 or 2 greenish flowers in the leaf axils. Mostly in 
rich soil. 
20. P. exsertum, Small. (Fig. 4, pl. 34.) Lona Fruirep KNOTWEED. 
Plant about 2 ft. high, slender but erect; leaves similar to P. aviculare, 
ete. The sheaths at the nodes divided into long silvery points. The 
3-angled seed projects much beyond the hull, hence the name. Brackish 
marshes, Maine to New York. 
B. Leaves of extremity of stem reduced and transformed to bracts. 
Plants mostly erect 
21. P. ramosissimum, Michx. Busny Knotweep. Plant erect, often 
3 or 4 ft. high, yellowish-green. Leaves similar to preceding species, 
inter-nodes usually shorter than leaves. Collaret fringed in long coarse 
points which arise from lacerations, Saline soil, coast from Maine to 
New Jersey. 
22. P. tenue, Michx. (Fig. 2, pl. 34.) SLENDER KNoTwEeEpD. Stem 
slender, angled, $ to 1 ft. high, smooth; leaves linear, from + to 1 in. 
long with a lateral impression or fold on either side of the mid-vein. 
Flowers green in axils of leaves, pointing upward. Dry soil; generally 
distributed. 
23. P. Douglasii, Green. Dovucias’s Knotweep. Similar to No. 20, 
but leaves broader and without the folds. The flowers at the leaf axils 
point downward. Northern New York and Vermont. 
C. Leaves arrow-shaped, egg-shaped or halberd-shaped. All heart-shaped 
at base. Plants climbers or trailers 
24. P. convolvulus,L. (Fig. 8, pl. 34.) Brack Binpweep. Stem 
somewhat angular; leaves egg-shaped or arrow-head-shaped, upper ones 
lance-shaped, tapering at apex. The angles of the seed hull either with- 
out wings or very slightly winged. Flowers in pendulous spreading 
clusters at leaf axils, green. The plant trailing or twining. Common in 
waste grounds, 
25. P. cilinode, Michx. (Fig. 12, pl. 34.) Frrneczp BiLack Brnp- 
WEED. Leaves broad egg-shaped or spear head-shaped; collarets fringed 
with depressed bristles, not at border but near the base. Clusters of 
flowers on stems only slightly spreading or branching. Plant generally 
twining or trailing over stone fences, ete. 
Var. erectum, Peck. Rocky places; generally distributed. 
26. P. scandens, L. (Fig. 6, pl. 34.) Crimpine FaLtsE BucKWHEAT. 
Vine, sometimes 20 ft. high, smooth. Leaves egg-shaped, heart-shaped 
at base, sharp pointed. Seed hull conspicuously winged at the angles, 
the wings with entire borders. Fruiting calyx about 4 in. long. Woods 
and thickets. Common. The form P. dumetorum, L., fruiting calyx about 
} in. long, occasional in our region and very similar to P. scandens. 
27. P. dumetorum, L. (Fig. 9, pl. 34.) Crestep Fase Buck- 
WHEAT. (VP. cristatum, Engelm. and Gray.) Vine similar to No, 24, 
