l62 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



From the above notes on these type specimens it will be 

 seen that the character which has been relied upon as dis- 

 tinctive of S. timhellife7'um^ namel}^ " hairs branched," is 

 only partially apphcable, not one of them being without a 

 considerable admixture of unbranched hairs. Indeed, I 

 have not been able to find a single specimen of this species, 

 among the many examined, in which more or less unbranched 

 hairs could not be detected. On the other hand, man)'^ 

 plants are found with a few, often a very few, branched 

 hairs intermixed with the prevalent simple hairs. More- 

 over, the character of the pubescence, at least in most 

 specimens of S . umheUifcruin, is different on the various 

 parts of the same plant. On the young stems, notably 

 towards the tips, it is exclusively, or nearly so, of many- 

 branched hairs, while on the leaves, notably on the older 

 ones, it is largely, sometimes exclusively, of unbranched 

 hairs. ^ 



A more satisfactory character is found in the structure 

 of the hairs. In ^S". umbeUifcrum these, whether branched 

 or unbranched, are without cell divisions and are not 

 glanduliferous. In the plants which have been referred 

 to S. xanti the hairs consist of elongated cells, some of 

 the cells usually evacuate and collapsed, or atrophied, so 

 that the hairs have a peculiar unevenness; many of them 

 are tipped with black globular glands, causing the plant to 

 be more or less viscid. In glabrate forms the hairs are very 

 short and mostly reduced to a single cell, but they remain 

 glanduliferous. Unfortunately, this character is not entirely 

 constant, and it is possible to find specimens on which 

 there are branched hairs which are also plurilocular and 

 glanduliferous. 



The leaves of the group exhibit a wide range of variation 

 in shape, passing from orbicular to oval, oblong, elHptical, 

 and even lanceolate; the apices are either acute or rounded. 



1 In a specimen collected by Kellogg and Harford near Bear Harbor, ou the northern 

 coast of California, a third form of hair occurs on the oldest stems. These are densely 

 tomentose with the usual mixture of branched and unbranched hairs, from which stand 

 out scattered spinose branched hairs, 2-4 ram. long. 



