BUCKWHEAT FAMILY 
57 
Leaves slightly undulate; fruiting sepals with a narrow wing 
bordering the callous grain. 3. R. conglomeratus. 
Leaves plane; fruiting sepals triangular, usually much larger 
than the callous grain.4 .R. salicifolius. 
Inner fruiting sepals with prominent slender teeth or bristles ; callous grains 
1 to 3.5. R. pule her. 
Flowers dioecious; roots red, scentless; pedicels not jointed. 6. R. acetosella. 
1. R. hymenosepalus Torr. Canaigre. Stem nearly simple, 3 to 5.8 
dm. high; leaves oblong or tapering to each end, somewhat wavy-mar- 
gined; sheathing stipules conspicuous; panicle dense; pedicels jointed 
near the middle, shorter than the fruit.—Dry sandy washes and sandy 
plains. 
2. R. crispus L. Curly Dock. Stoutish, about 5.8 dm. high; 
leaves elliptical to oblong-lanceolate, wavy-margined; flowering branches 
strict, with few leaves, the whorls dense and mostly crowded; pedicels 
twice as long as the fruit, jointed near the base, recurved (as also in the 
next) : inner sepals in fruit bearing (as also in nos. 3 to 5) callous-like 
grains or 1 or 2 naked.—Weed, nat. from Eur. 
3. R. conglomeratus Murr. Green Dock. Stems slender, 8.6 to 14 
dm. high; leaves ovate or mostly oblong, slightly undulate; flowering 
branches very long, naked or with a leaf subtending some or all of the 
remote whorls; pedicels as long as or shorter than the fruit; callous 
grains mostly 3 and smooth.—Valleys. • 
4. R. salicifolius Weinm. Willow Dock. Stems commonly tufted, 
about 5.8 dm. high; leaves plane, glaucous, lanceolate, acute at both ends; 
flowering branchlets short (4.8 cm. long), with dense crowded and leafless 
whorls, or 1 or 2 lower whorls remote and leafy; pedicels rather shorter 
than the fruit.—Valleys. 
5. R. pulcher L. Fiddle Dock. Stem slender but rigid, widely 
branched above, the branches zigzag; leaves oblong or fiddle-shaped; 
flowering branches simple, divaricate, sparsely leafy, the dense whorls 
remote; callous grain often solitary.—Wayside weed, nat. from Eur. 
6. R. acetosella L. Sheep Sorrel. Stems tufted: staminate and 
pistillate flowers on different plants.—Weed, nat. from Eur. 
4. RHEUM L. 
Perennial herbs. Leaves large, rounded, mostly basal. Flowers white, 
in long panicles. Stamens 9 or 6. Ovary 3-angled; styles 3; stigmas 
capitate or cuneate. (Greek rha, the ancient name.) 
1. R. rhaponticum L. Garden Rhurarb. The large fleshy stalks, 
filled with most excellent acid juice, are cooked in late winter and spring 
as a substitute for fruit.—Native of southern Siberia. 
5. PTEROSTEGIA F. & M. 
Slender weak diffuse annual with dichotomous stems and opposite 
leaves. Flowers solitary and sessile in the axil of a bract-like involucre. 
Involucre rounded and 2-lobed or -toothed, in fruit becoming enlarged 
and thin, loosely inclosing the achene and bearing 2 sac-like protuber¬ 
ances on the back. Calyx commonly 6-parted. Stamens 3 or 6. (Greek 
pteron, a wing, and stege, a covering, in reference to the bract.) 
1. P. drymarioides F. & M. Leaves roundish and notched at apex 
