POLYGON ACE AE (BUCKWHEAT FAMILY) 155 



about 2 mm. long. Introduced everywhere in the east, and to some extent 

 in our range. 



11. Rumex persicarioides L. 1. c. Annual, simple, or diffusely branched, 

 the low stems erect or procumbent, minutely pubescent: leaves linear- 

 lanceolate, usually truncate or cordate at base, 3-10 cm. long, mostly on 

 short petioles, somewhat wavy-margined: flowers in numerous dense verticils 

 along the slender branches: valves ovate-lanceolate, with 2 or 3 long-awned 

 teeth on each side, all grain-bearing. R. maritima. Mostly in saline soils; 

 transcontinental. 



12. Rumex densiflorus Osterh. Erythea 6: 13. 1898. Stout erect glabrous 

 scarcely branched perennial, from thick horizontal rootstocks; stems clustered, 

 grooved, 5-10 dm. high: lower leaves very large, 1.5-3 dm. long, 10-15 cm. 

 wide, usually very obtuse, long-petioled ; upper leaves gradually reduced: 

 flowers in dense clusters, terminating the stem and its branches, polygamous 

 or dioecious: calyx usually red; the anthers brown: valves naked; the wings 

 broadly ovate, shorter than the pedicels: achene ash-color. Stream banks at 

 high elevations; Colorado and Wyoming. 



13. Rumex polyrrhizus Greene, Pitt. 4: 305. 1901. Slender sparingly leafy 

 perennial, 5-10 dm. high: stem solitary from a short vertical crown surmount- 

 ing a small fascicle of fleshy roots, usually a whorl of fibrous roots near summit 

 of crown: leaves from lanceolate to linear, 12-20 cm. long, on petioles usually 

 shorter than the blade, flat or crisped near the base: panicle strict but rather 

 loose; pedicels slightly enlarged upward, jointed well above the base: valves 

 thin, venulose, the margin obscurely crenate-dentate. (R. Bakeri Greene, PI. 

 Baker. 3: 15. 1901; R. praecox Rydb. Bull. Torr. Bot. Club 33: 137. 1906.) 

 Wet mountain meadows; Colorado and Montana. 



14. Rumex occidentalis Wats. Proc. Am. Acad. 12: 253. 1876. Mostly 

 6-9 dm. high, rather stout, subsimple: leaves somewhat fleshy, glabrous, 

 glossy, bluish-green, wavy margined, the lower very largf, ovate or mostly 

 oblong-ovate, truncately cordate, the apex rounded to subacute: panicle strict, 

 dense and rosy in fruit, naked or with a few small leaves below; whorls some- 

 what remote but overlapping; pedicels 2 to 3 times as long as the fruit : valves 

 sometimes rosy, 5-6 mm. long, deltoid-ovate, often only slightly cordate, re- 

 motely erose or denticulate, rounded or obtuse at apex, without callosities. 

 [R. subalpina Jones, Proc. Cal. Acad. II. 5: 720. 1895.] Texas to Ontario 

 and California. 



4. POLYGONUM L. KNOT-WEED 



Terrestrial, amphibious, or aquatic herbaceous (ours) annuals or perennials 

 with fibrous roots, or tuberous or thickened rootstocks. Stem simple or 

 branched, more or less swollen at the numerous nodes, erect, prostrate or 

 climbing. Leaves alternate and entire ; sheaths truncate or oblique at sum- 

 mit, lobed, lacerate, or fringed. Flowers axillary-racemose or spicate; pedi- 

 cels jointed. Calyx mostly 5-parted, the divisions often petal-like, all erect 

 in fruit, persistent. Stamens 4-9. Styles or stigmas 2 or 3; achene accord- 

 ingly lenticulate or 3-angular. 



Key to the Sections 



Flowers in terminal spikes, with scarious bracts; fila- 

 ments filiform. 



Roots tuberous, or fleshy rhizomes .... I. BISTORTA. 



Roots fibrous ! II. PERSICARIA. 



Flowers axillary, or racemose with foliar bracts. 



Stems not climbing . III. AVICULARIA. 



Stems climbing ....... IV. BILDERDYKIA (TINIARIA). 



BISTORTA. Perennials of northern or subalpine distribution. 



Rootstock elongated; spike floriferous throughout . . 1. P. bistortoides. 



Rootstock corm-like; spike bearing bulblets .... 2. P. viviparum. 

 PERSICARIA. Annuals or perennials, mostly of southern and 

 of middle to lower altitudes. 



