576 POLYGONACEjE pterostegia 



polygonum 



forming irregular whorls at the lower joints: involucres in the lower axils 

 few, without scarious margins, the upper in condensed capitate heads, with 

 equal broadly expanded scarious winged divisions, reflexed, rotate and 

 tipped with a slender uncinate awn, the tube ribbed and protuberant below 

 flowers 2-3, one with long pedicel partly exserted, the others undeveloped: 

 flowers short tubular, hairy outside, the segments oblong, equal : stamens, 

 at the base. On rocky foothills southern Oregon to California. 



C. Watsoni T. & G. Proc. Am. Acad, viii, 199. Canescently pubescent 

 throughout: stem erect or ascending, 1-4 inches long, branching from the 

 base : radical leaves narrowly oblanceolate to spatulate, 6-10 lines long, 

 narrowed to a petiole with dilated base, the margins revolute, densely 

 tomentose beneath ; lower cauline similar, but smaller and uncinately 

 awned, passing above into opposite uncinate-tipped bracts : involucres 

 clustered on the upper branches, narrow, inconspicuously costate, unequ- 

 ally 5-lobed, one 3-4 times as long as the others, all uncinate tipped: 

 flowers solitary, slender-pedicelled, included or partly exserted. the seg- 

 ments oblong, acute, pubescent outside: stamens inserted on the throat of 

 the calyx: achenes oblong-triangular. On desert districts, southeastern 

 Oregon to Nevada and California. 



4 PTEROSTEGIA F. & M. Ind. Sem. Petr. ii, 48. 



Very slender and weak diffusely and dichotomously branched 

 annuals with opposite entire or 2-lobed leaves and small flowers 

 solitary in foliaceous sessile involucres in the forks of the bran- 

 ches. Involucre of a single bract, subtending and shorter than 

 the sessile flower, rounded and more or less 2-lobed, at length be- 

 coming enlarged, scarious and reticulated, loosely enveloping the 

 achene, and gibbously 2-saccate on the back. Calyx 5-6-parted, 

 the segments equal. Stamens inserted at the base of the seg- 

 ments, as many or fewer. Achene triangular, glabrous. Cotyle- 

 dons rounded, accumbent upon the radicle. 



P. dryinarioides F. & M. 1. c. Sparingly hirsute: stems decumbent, 

 often 1-2 feet long: lower leaves petioled, 2-(5 lines broad, fan-shaped, 2- 

 lobed, the lobes crenately toothed or again lobed ; upper leaves obovate to 

 spatulate, entire or toothed : bracts similar, aline long: involucres very 

 small, becoming 1-1K lines long in fruit, somewhat 2-lobed, the margins 

 toothed or laciniate : flowers yellowish the segments oblong-lanceolate. 

 Hillsides and dry places, 'from the Columbia river to Lower California, i 



Tribe % Polygonacex Endl. Gen. 301. Herbs ivith alternate 

 leaves and scarious sheathing stipules. Flowers without involucre. 

 3-6-parted. Stamens mostly 4-8. Styles 2 or 3. Juice usually 

 pungent, acrid or acid. 



5 POLYGONUM L. Sp. 359. 



Annual or perennial plants with jointed stems, alternate leaves 

 scarious sheathing stipules, called ocrese, and small normally 

 perfect flowers in spikes, racemes or panicles. Calyx 4-6-parted. 

 or 4-()-cleft, the outer sepals or segments somewhat longer than 

 the inner. Stamens 8-9, included or exserted; filaments filiform, 

 or dilated at base, glabrous. Style 2-3-cleft or 2-3-parted, with 

 capitate stigmas. Achenes lenticular or 3-angled, rarely 4-angled, 

 invested by or exceeding the persistent calyx. Embryo near the 



