OF ARTS AND SCIENCES. 99 



temperate species for which Nuttall's specific name of divaricatus was 

 adopted by Torrey and Gray is A. exilis of Elliott. A. subulatus, 

 Michx., is a name for the other species preferred to A. linifolius^ L. ; 

 for the true original of the Linniean plant is a Galatella. This 

 species, with its inconspicuous rays, hardly surpassing the disk and 

 commonly surpassed by the mature pappus, and with its fewer disk- 

 flowers, must be held to invalidate the genus Brachyactis, which is 



§11. CoNYZOPSis, Torr. &. Gray, This name having been used 

 in this sense, as the name of a section, before the generic name Brachy- 

 actis was published, should be continued by those who do not admit 

 the latter genus. It is. as it were, the analogue of the section Tri- 

 morphcBa in Erigeron. Tlie American species are A. frondosus and 

 A. angmtus, Torr. & Gray. Brachyactis robusta, Benth., by its in- 

 volucre, flat and nerved-margined achenia, and no ligules, appears to 

 be a Conyza ; besides its pappus is distinctly double. B. menthodora, 

 Benth. (Hook. Ic. PI. t. 1106) seems to be a true perennial Aster. 



§ 12. Mach^ranthera. One division of this is the genus Ma- 

 chcerayithera of Nees ; the other is the genus Dieteria of Nuttall. 

 Except for the biennial or annual root, and the disposition to have 

 spiuulose-toothed or cleft or dissected leaves, this subgenus would rank 

 among the true Asters in the early part of the first series. A. gymno- 

 cephalus (Aplopappus, DC.) is a common Mexican species. As we 

 receive it A. canesceris, Pursh, would appear to comprise three or four 

 species, the extreme forms being widely different. These are arranged 

 as varieties, under the heads of var. viridis (the MachoEvanthera ca- 

 nescens, var. glabra. Gray, Pi. Wright, i. 89, etc.) ; var. latifolius (M. 

 canescens, var. latifoUa, Gray, Pi. Wright, ii. 75, and Dieteria aste- 

 roides, Torr. in Emory Rep. 142) ; var. viscosus, to which belongs 

 Dieteria viscosa and sessilijlora, Nutt., and D. incana, Torr. & Gray 

 {Diplopoppus incanus, Lindl. Bot. Reg. t. 1 693, & Hook. Bot. Mag. t. 

 3382) ; and var. tephrodes, of Southern California, Arizona, and New 

 Mexico, which was named A. incaniis in the Botany of California, 

 but which cannot be Lindley's plant. 



Among the true Asters are several forms which have to be named, 

 such as A. Porteri for A. ericoides, var. strictus, Porter & Coult. FI. 

 Colorad. 56, and A. Pringlei, from the northern end of Lake Cham- 

 plain, — species allied to A. ericoides. One species of Oregon is so 

 well marked that it may here be characterized : — 



Aster Cusickii. Cinereo-pubescens, pube molli nee scabra ; 

 caulibus simplicibus vel apice ramosis 1-2-pedalibus usque ad 

 capitula solitaria majuscula foliosis ; foliis amplis (inferioribus poll. 



