Rumex. POLYGONACE^E. 7 



TRIBE I. POLYGONEjE. Flowers without involucre. Perianth 3-6-parted. Stamens 

 mostly 4-8. Styles 2 or 3. Herbs with alternate leaves and scarious sheathing stipules ; 

 juice usually acid, acrid or pungent. 



1. Oxyria. Sepals 4, the outer smaller and spreading. Stigmas 2, tufted. Akene orbicular- 



winged. Leaves reniform. 



2. Rumex. Sepals 6, the outer spreading, the inner enlarging and appressed to the triangular 



akene. Stigmas 3, tufted. 



3. Polygonum. Sepals 4 to 6, equal, appressed to the triangular or lenticular akene. Styles 



2 or 3 ; stigmas capitate. 



TKIBE II. ERIOGONE^E. Flowers involucrate (except in Lastarricea). Perianth 3- 6-parted, 

 -cleft or -toothed. Stamens 3 to 9. Styles 3, with capitate stigmas. Herbs or woody at 

 base, with alternate or verticillate leaves (opposite and sometimes toothed in Pterostegia), 

 without stipules ; juice nearly tasteless. 



* Involucre unchanged in fruit or wanting : leaves entire. 

 +- Flowers capitate, subtended by distinct herbaceous bracts. 



4. Nemacaulis. Stamens 3. Akene ovoid. Annual, prostrate, with radical leaves. 



+- +- Involucre tubular or campanulate : perianth corolla-like, 6-cleft or -parted. 



5. Eriogoiium. Involucre several-flowered, with 4 to 8 pointless teeth. Flowers exserted. 



Stamens 9. Akene mostly 3-angled. Annuals or perennials. 



6. Oxytheca. Involucre few-flowered, herbaceous, with 3 to 5 straight, acute or usually awned 



lobes. Flowers on exserted pedicels, pubescent. Stamens 9. Akene lenticular. Bracts 

 ternate. Annuals. 



7. Chorizanthe Involucre 1- (rarely 2 -3-) flowered, coriaceous or chartaceous, 3-6-angled, 



with 3 to 6 cuspidate often hooked teeth and sometimes as many cuspidate divaricate spurs 

 at base. Flowers usually included. Stamens 3, 6 or 9. Akene 3-angled. Annuals. 



++-*- Involucre none : flowers somewhat axillary. Low annuals. 



8. Lastarriaea. Perianth tubular, subcoriaceous, cuspidately 6-toothed. Stamens 3. 



9. Hollisteria. Perianth campanulate, 6-cleft, white-woolly. Stamens 9. See page 481. 



* * Involucre bract-like, enlarged in fruit, 2-lobed, 1 -flowered, 2-saccate on the back. 



10. Pterostegia. Flower sessile, included. Leaves opposite, toothed or lobed. Slender annual. 



1. OXYRIA, Hill. MOUNTAIN SORREL. 



Flowers perfect. Perianth herbaceous, of 4 distinct sepals ; the 2 inner erect, 

 appressed and unchanged in fruit, the outer smaller and spreading. Stamens 6. 

 Stigmas 2, sessile, tufted. Akene compressed and thin, broadly 2-winged. Seed 

 flat. Embryo axile in the mealy albumen, slender. Perennial alpine and arctic 

 herbs, erect, with long-petioled round-reniform mostly radical leaves, and small ob- 

 liquely truncate scarious sheaths ; flowers small and greenish, in narrowly panicled 

 racemes. Meisner, DC. Prodr. xiv. 37. 



Only one species is known, in the mountains of Central Asia, besides the following. 



1. O. digyna, Campdera. Eather stout and fleshy, 3 to 18 inches high, gla- 

 brous : leaves an inch or two broad : flowers in scarious-bracted fascicles, on short 

 capillary pedicels : sepals often reddish, spatulate, thin, the outer half as long as 

 the inner ones, narrower and carinate : akene exceeding the sepals, 1| lines in diam- 

 eter, entire or emarginate at each end. 0. reniformis, Hook. 



At high altitudes in the Sierra Nevada, in cold wet places among rocks, and in like localities 

 throughout the northern hemisphere, northward to the Arctic Ocean. 



2. RUMEX, Linn. DOCK. SORREL. 



Flowers perfect or polygamous or dioecious. Perianth of 6 sepals, distinct or 

 nearly so, the outer 3 herbaceous, spreading or reflexed, the inner larger and some- 



