384 POLYGONACEAE 



Refs. POLYGONUM BIDWELLIAE Wats. Proc. Am. Acad. 14: 294 (1879), type loc. Chico, 

 Mrs. John Bidwell; Small, Monog. N. Am. Polygonum, 146, pi. 60, fig. 2 (1895). 



24. P. convolvulus L. BLACK BINDWEED. Twining or trailing annual, the 

 stems 1 to several feet long ; herbage glabrous, pale green ; leaves 1 to 2 inches 

 long, ovate, sagittate at base, acuminate at apex; flowers in axillary clusters 

 or disposed in a raceme ; calyx 5-cleft, in fruit minutely scurfy, closely invest- 

 ing the black achene. 



Naturalized from Europe: Sisson; Ft. Bidwell; Yosemite; San Francisco. 



Eefs. POLYGONUM CONVOLVULUS L. Sp. PI. 364 (1753), type European; Small, Monog. 

 N. Am. Polygonum, 148, pi. 61 (1895). 



2. RUMEX L. 



Weed-like herbs, ours perennial except one. Leaves mostly basal, those on 

 the stem alternate, the petioles with somewhat sheathing stipules. Flowers 

 mostly greenish, sometimes reddish or yellowish, pediceled and borne in 

 usually crowded whorls along the branches of the panicle. Calyx of 6 

 nearly distinct sepals, the 3 outer spreading or reflexed, the 3 inner larger, 

 continuing to grow after flowering and hugging the achene, 1 or more of them 

 in many of our species bearing a wart or callous grain on the back. Fruits, 

 therefore, more conspicuous than the flowers. Stamens 6. Styles 3, short; 

 stigmas tufted (wind-pollinated) and maturing before the stamens. Achene 

 triangular. About 110 species, all continents but mainly north temperate. 

 (Old Latin name used by Pliny.) 



Flowers perfect or some staminate on the same plant; inner sepals commonly reticulated, in 

 fruit becoming much longer than the achene; pedicels jointed; roots yellow, scented, 

 bitter. LAPATHUM DC. (Docks). 

 Inner fruiting sepals entire (or nearly so) and 



Without callous grains; pedicels not very prominently jointed. 

 Leaves rounded to acute at base. 



Inner fruiting sepals broader than long 1. B. venosus. 



Inner fruiting sepals longer than broad 2. B. Jiymenosepalus. 



Leaves cordate at base 3. It. occidentalis. 



With callous grains (or 1 or 2 of the sepals naked), 1 to 2y 2 lines long; pedicels 



prominently jointed near the base. 

 Leaves strongly undulate, elliptical to oblong-lanceolate; fruiting sepals with a 



broad wing bordering the callous grain 4. B. crispus. 



Leaves slightly undulate; callous grain nearly covering fruiting sepals, leaving 



only a narrow wing. 



Leaves linear, spatulate or oblong; callous grain toothed.. 5. B. berlandieri. 



Leaves oblong or ovate; callous grain not toothed. .. .6. B. conglomerate. 



Leaves plane, mostly lanceolate; fruiting sepals triangular, usually much larger 



than the callous grain 7. B. salicifolius. 



Inner fruiting sepals with very prominent slender teeth or bristles; callous grains 1 to 3. 

 Perennial; flowering branches elongated and 



Spreading at wide angles; pedicels jointed near the middle 8. B. pulcher. 



Suberect; pedicels jointed near the base 9. B. obtusifolius. 



Annual; flowering branches usually short, the whorls mostly spicate-crowded ; pedicels 



jointed near the base 10. B. persicarioides. 



Flowers dioecious; callous grains none or minute; roots red, scentless. ACETOSA DC. (Sorrels). 



Leaves not lobed; sepals longer than achene; pedicels jointed 11. B. paucifolius. 



Leaves hastate; sepals shorter than achene; pedicels not jointed 12. B. acetosella. 



1. R. venosus Pursh. Stems erect, % to 1% feet high, from a running 

 rootstock; leaves ovate or lanceolate, 2^ to 4 (or 6) lines long,- on short 

 petioles, with conspicuous dilated stipules; panicle nearly sessile, short, dense 

 in fruit ; inner fruiting sepals entire, without grains, round-cordate, 6 to 8 lines 

 long and 8 to 14 lines broad. 



Dry sandy valleys: Honey Lake Valley, Lassen Co., not otherwise known 

 in California. Nevada north to "Washington and east to Missouri. 



Eefs. EUMEX VENOSUS Pursh, Fl. 2: 733 (1814), type from the Missouri Eiver region; 

 Trel. Eep. Mo. Bot. Gard. 3: 79, pi. 17 (1892). 



2. R. hymenosepalus Torr. CANAIGRE. Stem 1 to 2 feet high, nearly 

 simple, arising from a cluster of 2 to 12 tuberous or dahlia-like roots and end- 



