V. PLANTS WRIGHTIAN^. 113 



sometimes three-winged, but often only two-winged, the wings sometimes half as 

 wide as the body of the achenium. The disk-achenia are sometimes almost as 

 broadly winged, sometimes Avith the wings very narrow or obsolete, except at the 

 apex, where they project in an obcordate form : they are separated from the pappus 

 by a narrow neck or sinus. The awns vary greatly in length, and are occasionally 

 little longer than the firm, calyculate, lacerate crown with which their bases are con- 

 fluent, but they are commonly elongated, at least one of them. Except for the 

 awns and the wings of the achenium (which appear also in W. helianthoides, 

 H.B.K.), the plant would evidently fall into Wedelia; indeed, its whole aspect is 

 that of Wedelia hispida, H. B. K. — This species and the preceding, with Lipochseta 

 strigosa, DC, so perfectly accord with the generic characters of Zexmenia of Llave 

 and Lexarza (doubtfully referred by De Candolle to his Lipochseta) that I feel 

 obliged to restore that genus ; the more so, as they are apparently not congeneric 

 with the Sandwich Island species, for which in strictness the name should be re- 

 tained, the oldest species being a Lipotriche of Lessing.* Moreover, Lipochseta 

 umbellata, DC, which might claim the generic name from its being the species 

 figured in Delessert's Icones, is surely a congener of De Candolle's Lasianthtea, not- 

 withstanding its smaller capitula. Again, there are some species closely allied to 

 Lasianthtea helianthoides, but with a pauciserial involucre, which would also accord 

 Avith the character of Zexmenia. Since the genus which is to comprise these plants 

 must needs be remodelled and extended, it is best to revive at once the oldest 

 name.f 



* For these, however, Nuttall has established his genus Microchseta (which has priority over MicrochEete 

 of Bentham) ; and Macrffia, Hook.Jil. is probably not distinct. They are very closely related to Wollas- 

 tonia, DC, and perhaps not to be separated from that genus. At least Nuttall's Microchseta procumbens 

 and M. strigulosa (VVollastonia procumbens and W. strigulosa) are genuine species of Wollastonia. 



t Zexmenia (Lasianth^a) helianthoides : foliis ovato-oblongis ovatisve basi nunc subcordatis brevi- 

 ter petiolatis subserratis reticulatis supra buUatis strigiUoso-puberis subtus cauleque velutino-villosis ; capi- 

 tulis 5-7 in umbellam foliis fulcrantem congestis singulis breviter pedunculatis ; involucro 4-seriali, 

 squamis omnibus ovatis appressis inappendiculatis ; ligulis aureis ; lobis corollfe intus barbatis ; filamentis 

 villosulis ; paleis intermediis pappi conspicuis inter se et cum aristis (deorsum alls confluentibus) coalitis. — 

 Lasianthus helianthoides, Zucc. in herb. Acad. Monac. Lasianthsea helianthoides, DC. Prodr. 5. p. 608. 

 — Mexico, /lariiu'nsi'i ; and near Cuernavaca (Valtadolid), &c., Ghiesirecht (v. sp. in herb. Par. No. 

 379, 150). — Heads three quarters of an inch long, on stout peduncles ; involucre over half an inch in 

 diameter. Palece of the receptacle shorter than the involucre, much shorter than the long and slender 

 disk-corollas. 



Z. (Lasianth^a) Greggii (sp. nov.) : foliis ovato-lanceolatis acuminatis serrulatis reticulatis scabris 

 basi cordata sessilibus, floralibus parvulis ; capitulis 3 umbellatim disposilis pedunculis dimidio terve brevi- 

 oribus ; involucro late campanulato triseriali, squamis omnibus ovatis inappendiculatis appressis ; ligulis 

 auriantiacis brevissimis; corollce disci lobis puberig ; filamentis glabris ; pappi paleis intermediis conspicuis 

 inter se et cum aristis basi in alam ciliatam extensis coalitis. — Between the city of Mexico and Mazatlan, 

 Gregg. — Heads half an inch in length and breadth ; the involucre much like that of the preceding. 

 Rays, in the specimen, not longer than the disk-flowers. Pappus as in Z. helianthoides. 



Z. (LasiantHjEa) Ghiesbrechtii (sp. nov.) : foliis ovato-lanceolatis acuminatis serrulatis reticulatis sub- 

 membranaceis hirtulo-scabris basi subcordatis breviter petiolatis ; pedunculis solitariis ternisve foliis sum- 

 mis duplo capilulo pluries longioribus superne incrassatis ; involucro hemispha;rico triseriali, squamis inap- 

 pendiculatis exterioribus rotundo-ovatis appressis ; ligulis (ut videtur aureis) disco pauUo longioribus ; pappi 



