166 MR. NUTTALL'S DESCRIPTIONS OF NEW 



length, almost disposed in a simple series; the achenium is also lanuginous, and the 

 seed presents, as in E. tomentosum, a concentric embryo. For E. longifolium I 

 would therefore propose the name of Trachytheca, excluding every other species. 

 It is the first species of the section Eriantha of Bentham, which name, in not being 

 exclusive, and too near Erianthus, cannot properly be employed for the present plant. 

 It is very peculiar in its solitary leaves and alternate branches. 



In all the rest of this numerous genus, the outer segments of the perianth, which 

 increase a little in size, are either larger and erect, or all nearly equal. In these, 

 some of which have the embryo excentric and others concentric, the subgeneric name 

 of Olygogonum may be applied, but whether any other subdivision may be made by 

 the condition of the embryo is at present uncertain. In E. flavum I believe the 

 embryo is excentric, but how far that species connects itself to any others of similar 

 form, remains to be examined. 



*EUCYCLA.t 



Perianth membranaceous, coloured, petaloid, dimorphous, the three outer divisions 

 orbicular, concave ; the three inner linear-oblong, emarginate, connivent into a 

 cylinder. Stamens nine; with short filaments, membranous at base. Styles three, 

 of moderate length, with small, capitate stigmas. Achenium attenuated, triangular. 

 Embryo excentric ; radicle superior ; cotyledons flat. 



E. *ovALiFOLiA. — Leaves all radical, short and roundish-ovate, whitely tomentose ; capitulum made up of 

 several sessile, whitely tomentose involucres ; outer segments of the yellow perianth rather narrower 

 at base, the inner emarginate segments exserted. 



Erigonum ovalifolium. Nutt. Journ. Acad. Nat. Sci., Philad. 

 Hab. Sources of the Missouri. Flowers bright yellow. 



E. *PURPUREA. Leaves all radical, short and roundish ovate, whitely tomentose ; capitulum made up of 

 several sessile, smoothish, tomentosely margined involucres; outer segments of the purple perianth 

 orbicular, sometimes emarginate at base ; the inner emarginate, narrow, segments scarcely exserted. 



Scape about a span high, arising from a multifid woody caudex ; flower larger than 

 in the preceding, and purple ; filaments much shorter than the perianth, with a torn 

 membranous margin, at base three stamens seated on each of the inner narrow 

 segments ; embryo rather short. 



Hab. Rocky Mountains. 



CHORIZANTHE. 



C. *NUDiCAtrLE. Annual ; radical leaves narrow spathulate, pubescent, with long, slender petioles, 

 tomentose beneath ; scapiform stem nearly naked, the summit trichotomous, the branchlets once or 

 twice bifid, the flowers cymosely conglomerated ; stem and very unequal toothed invokicrum 

 lanuginous; segments of the sessile exserted, perianth oblong, obtuse. 



f In reference to the circular figure of the perianth. 



