POLYGONACBAE (BUCKWHEAT FAMILY) 147 



2. Comandra pallida A. DC. Prodr. 14: 636. 1857. Stems 1-2 dm. high, 

 arising at somewnat regular intervaJs from the horizontal rootstock, usually 

 simple: leaves glaucous, from oblong to nearly linear, usually acute, often 

 cuspidate: cymes corymbosely clustered, several-flowered; the perianth 

 greenish- white or purplish: fruit ovoid, 6-8 mm. high, sessile or on short stout 

 pedicels. — ^Frequent on dry sandy slopes and banks; widely distributed. 



36. POLYGONACEAE Lindl. Buckwheat Family 



Herbs (ours), trees, or shrubs with alternate or sometimes opposite or 

 verticillate entire leaves, and stipules in the form of sheaths above the swollen 

 joints of the stems, or none. Flowers rather small, mostly perfect, with a more 

 or less persistent calyx (perianth), coiisisting of 3-6 segments, the inner ones 

 or often all petaloid. Petals wanting. Stamens 4r-9. Ovary 1-celled, bearing 

 2 or 3 styles or stigmas. Fruit an achene, with a single erect seed. 



Flowers subtended by aa involucre; sheaths none 1. Erigonuiu, 



Flowers without involucre; sheaths present 

 Stigmas tufted. 



Sepals 4; stigmas 2; achene orbicular-winged 2. Oxyria. 



Sepals 6; stigmas 3; achene triangular 3. Rumex, 



Stigmas capitate, 2 or 3; achene lenticular or triangular . . .4. Polygonum. 



1. ERIOGONUM Michx. 



Annuals, or herbaceous or somewhat woody perennials, with radical or 

 alternate or verticillate leaves. Flowers small, fascicled, cymose, umbellate or 

 capitate, subtended by 5-8-toothed oblong, turbinate, or campanulate in- 

 volucres Perianth 6-parted, usually colored; its segments equal or unequal. 

 Stamens 9. Styles 3, with capitate stigmas. Achene mostly 3-angled. 



annuals. 



Stem leafy. 



Flowers white 1. E. annuum. 



Flowers yellow 2. E. salsuginosum. 



Leaves basal. 



One or more nodes of the stem inflated . . . . 3. E. inflatum. 

 The whole stem normal. 



Flowers erect 4. E. Gordonii. 



Flowers nodding 5. E. cemuum. 



PERENNIALS. 



BRACTS SEVERAL. FOLIACEOUS; LEAVES BASAL. 



Achenes membranously winged 6. E. alatum. 



Achenes not winged. 

 Flowers glabrous, umbellate at sunmiit.of the scape-like 

 pedimcle. 

 Peduncle with a medial whorl of leaves . . . 7. E. heracleoidea. 

 Peduncle naked. 



Flowers distinctly yellow. 



Leaves glabrate, at least above . . . , 8. E. umbellatum. 

 Leaves tomentose on both sides . . , . 9. E. Rydbergii. 

 Flowers ochroleucous. 



Calyx 8^0 mm. long 10. E. latum. 



Calyx 4-5 mm. long 11. E. subalpinum. 



Flowers pubescent, tunbellate on long scapes, or (in 

 No. 1 7) depressed-acaulescent. 

 Umbel irregularly proliferous. 



Flowers yellow 12. E. Bakeri. 



Flowers white 13. E, Jamesii. 



Umbel regular. 



Bracts conspicuous, 1-3 cm, long. 



Leaves thick; perianth narrowed abruptly at base. 



Crowns of caudex enlarged but not woolly . 14. E, flavum. 

 Crowns of caudex enlarged and woolly . . IS. E. crassifolium 

 Leaves thinner; perianth narrowed to a stipe- 

 like base 16. E. Fiperi. 



Bracts inconspicuous, less than 1 cm. long. 



Depressed-acaulescent . . . . . 17. E. acaule. 

 Subcaespitose with long slender scapes . . 18, E. Usbnogynum. 



