164 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



and absolute delimitations, which should exclude all inter- 

 grading forms, would reduce the whole group to a single 

 heterogeneous species, a disposition, it is safe to say, unac- 

 ceptable to any one who has studied these plants. Avoid- 

 ing these two extremes, I have attempted a classification 

 with reference to certain diverging lines of development 

 which are manifested, without insisting upon definite cleav- 

 ages, which do not exist. Such differences, as every 

 botanist is aware, are more easily perceived in the exam- 

 ination of copious material than characterized. In the 

 present instance the facts as they are in nature are repre- 

 sented by such a treatment; for we have here a series of 

 plants in which variation has outrun the processes of selec- 

 tion, and in which the connecting forms yet remain to unite 

 the diverging lines of evolution. It has also the advantage 

 of preserving the species recognized by Dr. Gray, who 

 with his accustomed discernment fixed upon the best diag- 

 nostic character, that of the pubescence, although it does 

 not possess the definiteness he seems to have supposed. 



To the group I have prefixed an Arizona plant with a 

 very different corolla, but with further characters shared 

 by the other members of it. 



Key to the Group. 



Corolla deeply 5-cleft; nodes of the peduncle obsolescent, i. 5. arizonicum. 

 Corolla angulately 5-lobed; nodes cupulate, prominent. 



Leaves mostly linear-lobed at base. 2. .S". temalobatuni. 



Leaves seldom lobed. 



Plants viscidulous; hairs unbranched. 

 Leaves crenate; corollas large. 



Stems long-hirsute. 3- S- wallacei. 



Hispidulous or glabrescent. 4. S. wallacei viridis. 



Leaves with entire margins. 



Acute or merely obtuse at base. 5. S. xanti. 



Cordate or subcordate at base. 6. 5". xanti intermedium. 

 Attenuate at base, small. 7. .S". xantt glabrescens. 



Plants not viscid; hairs branched. 



Stems villous. 8. 5. mnbelliferum. 



Stems canescently tomentose. 



9. S. umbelliferum. calif ornicutn. 



