BUCKWHEAT FAMILY 211 



Flowers in several racemes or panicles; rootstocks not tuberous-thick- 

 ened. 

 Racemes in terminal corymbs; plants smooth. 



Embryo in the center of the endosperm; leaves sagittate or 



cordate. 12. FAGOPYRUM. 



Embryo at one side of the endosperm; leaves neither sagittate 



nor cordate. 13. ACONOGONUM. 



Racemes not in terminal corymbs; plant prickly; embryo at one 



side of the endosperm. 14. TRACAULON. 



Herbaceous vines, with twining stems; sepals winged or keeled. 



15. BlLDERDYKIA. 



1. ERIOGONCTM Michx. UMBRELLA PLANT. 



Annual or perennial herbs or shrubby plants, with basal or cauline, alternate, 

 opposite, or whorled leaves and no stipules. Blades entire. Flowers perfect or 

 polygamo-monoecious, in involucrate clusters variously disposed. Involucres 

 turbinate or campanulate, rarely nearly cylindric, 4-8-lobed. Perianth more or 

 less colored, jointed to a short pedicel. Segments 6, in two series. Stamens 9; 

 filaments filiform, often hairy at the base. Ovary 1-celled, 3-angled or 3-winged; 

 styles 3. 



Achenes 3-winged; perianth not accrescent; perennials with a thick taproot and short 



crown. I. ALATA. 



Achenes merely 3-angled; perianth accrescent in fruit. 



Perianth with a stipe-like base; bracts verticillate, leaf-like. 



Involucres in branching cymes ; perennials with a branched woody caudex ; flower- 

 ing branches scapiform. II. ERIANTHA. 

 Involucres in simple or compound umbel-like or head-like clusters. 

 Perianth pubescent. 



Perianth yellow; leaf-blades spatulate or oblanceolate. 



Involucres undulate-dentate, tomentose, many, umbellate; embryo 



straight; perennials with a cespitose caudex. III. FLAVA. 

 Involucres deeply lobed, solitary, or 2 or 3 together; embryo curved; 



perennials, subacaulescent or suffruticose. IV. CAESPITOSA. 



Perianth white; leaf-blades ovate or elliptic; cespitose subacaulescent 

 perennials. V. PYROLAEFOLIA. 



Perianth glabrous; perennials with a cespitose caudex, with the leaves clustered 



at the ends of the branches. VI. UMBELLATA. 



Perianth without stipe-like base. 



Ovaries and fruit pubescent; involucres few, capitate or subcymose; perennials 



with scapiform stems. VII. LACHNOGYNA. 



Ovaries and fruit glabrous or nearly so. 



Involucres in head-like or umbellate clusters. 



Perianth-lobes very unequal; perennials with a pulvinate-cespitose woody 

 caudex. VIII. HETEROSEPALA. 



Perianth-lobes equal or nearly so. 



Heads solitary or, if more than one, proliferous-umbellate, with the 



central head sessile; cespitose perennials. IX. CAPITATA. 



Heads several, paniculate, corymbose or cymose-umbellate. 



Herbs with perennial caudices; heads paniculate, almost ebracteate; 



perennials with a stout roqtstock. X. ELATA. 



Leafy undershrubs, with fascicled leaves; heads cymose-umbellate ; 



suffruticose perennials. XI. FASCICULATA. 



Involucres in open cymes. 

 Bracts scale-like. 



Involucres, except those of the forks of the inflorescence, sessile, the 



uppermost conglomerate. 



Cymes repeatedly dichotomous or trichotomous. 

 Perianth-lobes very dissimilar; perennials. 



XII. DlCHOTOMA. 



Perianth-segments not very dissimilar. 



Perennials, shrubby at least at the base. 



XIII. CORYMBOSA. 



Annuals, with a strict herbaceous stem. 



XIV. ANNUA. 

 Cymes with more or less raceme-like branches. 



Perennials. XV. RACEMOSA. 



Annuals. XVI. VIRGATA. 



Involucres all peduncled, never conglomerate; scapose annuals (except 

 E. tenellum); leaves basal, petioled. XVII. PEDUNCULATA. 



Bracts leaf-like. 



Primary stem-leaves scale-like, with a pair or a fascicle of secondary 

 well-developed leaves in their axils; caulescent annuals. 



XVIII. DlVARICATA. 



Primary stem-leaves well-developed, also often with secondary leaves 



in their axils. 



Perianth petaloid, not closely investing the achenes; invo 

 toothed or lobed. 



