#*** Twining or climbing : petioled leaves cordate or sagittate: flowers in loose panicles or 
racemes or in terminal or axillary clusters: calyx green, with colored margins, 6 (rarely 
4)-parted: stamens mostly 8: styles or stigmas 3 (2 in No. 20). 
+ Annuals, somewhat climbing by reflexed prickles on the angles of stems and petioles: 
sepals (pale rose or white) not keeled: bracts chaff-like. 
90. P. arifolium L. (HALBERD-LEAVED TKAR-THUMB.) Stem grooved-angled: leaves 
halberd-shaped, taper-pointed, long-petioled: flowers somewhat racemed (few): pe- 
duncles glandular-bristly : calyx often 4-parted; stamens 6: styles 2, very short: 
achene lenticular (large).—Low grounds, sparingly introduced, 
21, P. sagittatum L. (ARROW-LEAVED TEAR-THUMB.) Stem slender, 4-angled, 
smooth (except angles): leaves sagittate, short-petioled: flowers capitate: pedun- 
cles smooth: stamens mostly 8: styles 3, slender: achene sharply 3-angled.—Wet 
places, more common than the last. 
+ Stems not prickly: calyx with the 3 outer divisions keeled, at least in fruit: flowers in 
loose corymbose or panicled racemes: bracts short-sheathing. 
29. P.Convolvulus L, (BLACK BINDWEED. ) Annual, twining or procumbent, low, 
roughish, the joints naked: leaves halberd-heart-shaped, pointed: flowers in small 
interrupted corymbose racemes: outer calyx-lobes keeled: achenes smoothish.—Cul- 
tivated and waste grounds, throughout the United States and Mexico. 
23. P. scandens L. (CLIMBING FALSE BUCKWHEAT.) Perennial, smooth: sheaths 
naked: leaves cordate or slightly halberd-shaped, pointed: racemes interrupted, 
leafy: the outer calyx-lobes strongly keeled and winged in fiuit, the wings somewhat 
crenate, but often one or all three wanting: achene over 3 mm. long, smooth and shin- 
ing. (P. dumetorum, var, scandens Gray.)—Moist thickets, extending from the 
Atlantic States into Texas. 
24. P. cristatum Engelm. & Gray. Leaves subcordate or truncate at base, trian- 
gular, acuminate, with scabrous margin: flowers glomerate in the axils of leaves or 
loosely disposed in leaty spikes; otter calyx-lobes winged in fruit, the wings cre- 
nately incised: achene small (2:mm.) and shining.—Near Industry (Lindheimer) ; aiso 
collected in South Carolina by Ravenel. 
3. OXYRIA Hill. (MouNTAIN SORREL. ) 
Low alpine perennial, with round-reniform and long-petioled leaves 
chiefly from the root, obliquely trun ‘ate sheaths, small greenish flow- 
ers clustered in panicled racemes on a slender scape, herbaceous calyx 
of 4 sepals unchanged in fruit, the outer smaller and spreading, but 
the inner broader and erect, 6 stamens, 2 sessile and tufted stigmas, and 
the thin lenticular achene (surrounded by a broad veiny wing) flattened 
contrary to the wing. 
1. O. digyna Hill. Rather stout and fleshy, 1 to 4.5 dm, high, glabrous: leaves 
notched at the end: flowers in scarious-bracted fascicles, on short capillary pedicels : 
sepals often reddish: fruit orbicular,—At high altitudes, in cold and wet places 
among the rocks, 
4. RUMEX L. (Dock.) 
Coarse herbs, with small and homely (mostly green) flowers crowded 
and commonly whorled in paniculate racemes, somewhat sheathing 
petioles, 3 outer sepals herbaceous and spreading in fruit, 3 inner ones 
somewhat colored and becoming reticulated (forming the valves) in fruit, 
6 stamens, and 3 tufted stigmas. 
