CALIFORNIA ACADEMY OF SCIENCES. 273 



for, if united to Erigonum, it is to be feared that the latter 

 will have to include the whole tribe. 



Nemacaulis has, for what appears to me sufficient reason, 

 been referred in the following pages to Eriogonum. The 

 new species, E. gossypinum, very much resembles it, and 

 has the involucre divided half way to the base. The simi- 

 larity of the internal bracts to those of E. angvlosum was 

 long ago pointed out by Dr. Gray, Proc. Am. Acad, viii., 

 146. 



In regard to those species in which the involucre consists 

 of distinct, unequal bracts (Lastarricea Ckilensis, Eemy., Hol- 

 listeria lanata, Watson, Oxytheca luteola, Parry, and perhaps 

 Eriogonum salsuginosum, Hook., which I have not seen, but 

 which, from the description, must be near 0. luteola), they 

 might perhaps be included in a genus to be characterized 

 by the involucre; or what would perhaps be more convenient, 

 included as a section in Oxytheca, two species of which, 0. 

 trilobata, Gray, and 0. caryophylloides, Parry, have their in- 

 volucres divided nearly to the base. 



As to the theory which has been advanced, that the peri- 

 gonium of Lastarricea is to be considered as an involucre, 

 with adnate, nearly obsolete perianth, I can only say, that 

 with some slight skill in the use of the microscope, I have 

 been unable to find any trace of such organ. 



The perianth of Lastarricea is quite similar to that of 

 Hollisteria; both are somewhat coriaceous, with accuminate 

 recurved segments, and the enclosing bracts have certainly 

 as much right to the rank of an involucro as those of 0. 

 luteola. 



The following section of Eriogonum, as far as the species 

 known to me, a very natural one, is proposed: 



§ Beacteolata. Flowers within the involucre each sub- 

 tended by a spatulate bract. Stems usually angular, leafy. 



Eeiogonum angulosum, Benth. Involucre many-flowered : 

 outer segments of the perianth rounded with inflexed mar- 



