44 CALIFORNIA ACADEMY OF SCIENCES. 



There is a perennial, acaulescent plant of northern habitat 

 which, although ndmitted by Dr. Gray into his superlatively 

 h^mplified Microseris, is, in my opinion, to be excluded from 

 8co7^zoneUa, to which it is more related than to any other 

 recognized genus. The palene of its pappus are soft and 

 slender, ending in a sharp, but hardly awn-like point: its 

 involucre has a peculiarity, and the heads are never nodding. 

 The specific name, troximoides, was given on account of the 

 close resemblance which the species bears to Troximon cus- 

 pidatum. But this last-named plant appears to be entirely 

 out of place in Troximon; for its pappus is composed, partly 

 of capillary bristles, and partly of very narrow palese. My 

 conclusion is, that these two plants will constitute the most 

 perfectly natural genus in the whole group, and I so place 

 them, adopting the name which Dr. Gray coined for sec- 

 tional use under his Microseris. 



The form of the akenes in these genera, whether turbinate 

 or cylindrical with truncate apex, or whether more or less 

 attenuate upwards, would seem to be of specific but not 

 generic importance. The basal callosity, although not very 

 seriously taken under consideration by Dr. Gray, appears to 

 have merited more deliberate attention; for, in Microseris, 

 as here defined, it manifests a character which runs through 

 all the species, without reappearing in any of the other gen- 

 era, except that there is a mere hint of it in Calais. 



The aestivation of the pappus is of one character in all the 

 genera. Whether the pale^e be five, or twice or thrice or 

 four times that number, one^is always wholly exterior, and 

 an opposite one interior, while all the others are regularly 

 convolute. In 3Ecrosersis alone the species fall into two 

 quite natural groups by a difference in the expansion of the 

 individual palea?. 



MICROSERSIS, Don. 



Involucre oblong-cylindraceous to hemispherical, inner 

 bracts in one or two series, equal, acuminate, tliin, with 



