COLOMUIAN EUPATOHIUMS. 269 



in Engl. Bot. Jahrb. xix. 45 (1S94), xxi. 329-333 (1895), xxix. 5-15 

 (1900), xxviii. 564-576 (1901), xl. 369-389 (1908); Heering in 

 Fuhrmann & Mayor, Mem. Soc. neuchat. Sci. Nat. v. 418-421 (1913). 

 For extended synonymy, see Dalla Torre & Harms, Gen. Siphonog, 

 527 (1905). — ]Mostly perennial herbs or erect shrubs, a few annuals, 

 a few arborescent or even arboreous, a few shrubby climbers (leaning 

 rather than twining). Leaves chiefly opposite, rarely alternate, 

 sometimes scattered, in a few species verticellatc or perfoliate, in 

 contour ranging from filiform to orbicular, in texture from delicately 

 membranaceous to coriaceous or rarely to fleshy. Florets clear white, 

 pink, purple, or blue, rarely greenish- or yellowish-white. 



A huge genus, most copiously distributed, both as to individuals and 

 species in the warmer parts of America, from Mexico to Brazil, also 

 well representefl in temperate North America and extra-tropical South 

 America, and sparingly so in Eurasia, but nearly absent from Africa 

 and lacking in Australia. 



Key to Sections. 



a. Receptacle glabrous b. 



b. Receptacle flat or nearly so c. 



c. Involucre cylindrical (2-) 3-5 times as long as thick; 

 scales closely imbricate in several regularly graduated 

 series, at maturity readily deciduous or sometimes cadu- 

 cous, firm in texture, somewhat scarious except toward 

 the usually obtuse or rounded and commonly subherba- 



ceous tip Sect. I. Cylindrocephala (p. 270). 



c. Involucre campanulate or turbinate (rarely cylindrical 

 but then with scales in fewer series and less closely im- 

 bricated than in the preceding section), seldom more than 

 twice as liigh as thick; scales persisting imtil after the 

 fall of the achenes d. 

 d. Scales very unequal, the outer gradually shorter in 3- 



several series Sect. II. Subimbricata (p. 281). 



d. Scales subequal in 1-2 scarcely imbricated series, but 

 often 1-3 of the outermost scales considerably smaller 



Sect. III. Eximbricata (p. 303). 

 b. Receptacle strongly convex, hemispherical or conical e. 

 e. Scales imbricated in several series, readily d'eciduous or 

 caducous at maturity, commonly falling away before the 

 achenes. Heads few, separate, long-peduncled. Annual 



herbs Sect IV. Praxelis (p. 318). 



e. Scales persistent, at least until after the fall of the achenes. 



Chiefly perennial herbs or shrubs /. 



/. Heads small (usually 4-7 mm. high), mostly 1.5-30- 



flowered. Scales 2-5-ribbed, usually graduated in 



3-4 series, mostly attenuate to a subulate or at least 



acute tip Sect. V. Conoclinium (p. 320). 



/. Heads large (1 cm. or more in height), 40-120-flowered. 

 Scales subequal in length, finely nerved or many-striate 

 rather than strongly ribbed. .Sect. VI. Campuloclinium (p. 325). 

 a. Receptacle hairy, convex Sect. VII. Hebeclinium (p. 327). 



