C. VI8CIDIFLORU8. 187 



analysis, but the nature of the distinguishing characters is such that it is believed to exist. 

 At any rate, the constant characters, if they occur at all, are so minute and unite in so 

 perplexing an array of combinations that the use of more than the most obvious of them 

 in taxonomic studies would lead only to hopeless confusion. One notable exception to 

 this is the presence or absence of a minute but dense puberulence on the upper portions 

 of the plants, particularly on the faces of the upper leaves and on the branches of the 

 inflorescence. When this is present at all it is usually very evident and in two cases it 

 occurs in subspecies each of which is matched almost exactly, except for this character, by 

 another of a similar geographic distribution. These two pairs of subspecies are: steno- 

 phyllus (glabrous) corresponding to puberulus (puberulent), and pumilus (glabrous) cor- 

 responding to lanceolatus (puberulent). This condition is very suggestive of an origin 

 of the glabrous varieties through mutation from their respective pubescent counterparts, 

 although an origin through gradual variation followed by isolation and a subsequent 

 reunion geographically after the characters had become fixed is not an excluded explana- 

 tion. A third pair of forms differing only by this same character is indicated by a col- 

 lection of typicus made by Grinnell 6 km. east of Jackass Spring, in the Panamint Moun- 

 tains of eastern California (Univ. Calif. Herb. 201227). In this collection one detached 

 branch is perfectly glabrous, while the other two, which match the first in every other 

 respect, are densely puberulent on the leaves and peduncles. A recurrence of this 

 variation is found in a collection of typicus from Mono Lake, California (Bolander 61^2, 

 in part; Univ. Calif. Herb. 31174 and 31175). The puberulence here referred to is not 

 to be confused with a scabrid or subciliate pubescence which often occurs on the margins 

 of the leaves and is quite erratic in its behavior. Since the criteria can be most con- 

 veniently discussed under the subspecies in which they occur, these are here taken up 

 seriatim. The accompanying diagram (fig. 26) has been prepared as an aid in elucidating 

 the probable relationships between the various subspecies, which discussion can best be 

 given along with that of the criteria. 



The subspecies lanceolatus comes the nearest of all to representing the'ancestral type of 

 the species. This conclusion is based upon the assumption that the green-leaved forms 

 preceded the pale-leaved ones, that both extremely wide and extremely narrow leaves 

 have followed as modifications from medium-sized leaves, and that both lack of pubes- 

 cence and thickening of the bracts are derived characters. If these assumptions are cor- 

 rect, then lanceolatus is the biologic type instead of typicus, which, however, must 

 still be retained as the nomenclatorial type. The connection between the two is indicated 

 by occasional specimens having all the characters of the former, except that they are 

 robust and tall as in typicus (Black Canon, Colorado, Baker 685). In order to provide 

 for these more robust plants it is necessary to expand somewhat the usual conception of 

 lanceolatus by admitting a considerable degree of variation in this regard. The type 

 specimens give no clue as to the size and Nuttall's original characterization of "a moder- 

 ate-sized shrub " is no more helpful. In the above citation of specimens under lanceolatus 

 all are of rather low stature, mostly under 4 dm., except those otherwise indicated. If 

 the tall plants really are distinct, they form another group close to typicus, but differing 

 in the close although minute puberulence. Experimental evidence is here much needed. 

 The origin of the other subspecies from lanceolatus has not proceeded from a single point. 

 On the contrary, it seems that the primitive form has produced others through variations 

 in several directions. One of these, which represents the end-point of one series of varia- 

 tions and is still in close contact with lanceolatus is pumilus. The origin of this from 

 lanceolatus, or vice versa, by mutation has been already suggested (p. 187). It is appar- 

 ently much less common than this and occurs farther from the center of distribution of 

 the species. Both of these facts, as well as its glabrous nature, would seem to indicate 

 that pumilus is the derivative, in case either one has arisen by mutation from the other. 



