1904] COPELAND—VARIATION OF CALIFORNIA PLANTS 407 
RHAMNUS CALIFORNICA Esch. 
In the foothills and mountains back of Palo Alto, R. calijornica 
and its var. omentella Brewer and Watson are scattered promiscuously 
and merge by insensible gradations. ‘The distinctions are supposed 
to be that the variety has tomentose reddish twigs, leaves yellow or 
white tomentose beneath, and peduncles longer than the petioles. 
My material was not collected at a season to illustrate the last feature. 
As to the others, individual shrubs possess or want them, so that a 
collector might easily gather material of the type or the variety; but 
in the field there is no constant relation between the color of the stem 
and the tomentum on the leaf, and neither green nor red twigs are 
likely to be glabrous. The leaves also vary notably in outline, apex, 
thickness, and margin, and in the rolling back of the sides. The 
most remarkable variability is in thickness and texture, margin, and 
Pubescence. I have measured the length, breadth, and length of 
petiole of all the leaves on one twig (one year’s growth) of twenty-eight 
shes. In the following table the results, averages for each bush, are 
atranged according to the shape of the leaves, the ratio of breadth to 
length, because this ratio is a feature that can be exactly expressed, 
a one that could not possibly have been considered in the collecting. 
This ratio is of average width to average length, and is usually larger 
than the average of the ratios for the individual plants. 
laa explanation of the table is as follows: under “margin” - 
hea € entire; under “‘lower surface” g is green and apparent glabrous, 
and moderately pubescent, w white (sometimes yellow) and very 
ane under “reflex” is given the per cent. of leaf folded back when pressed 
ome Hi Ang g is green, rg reddish-green, r reddish, rr red; thickness 1s. 
of a spherometer. 
aa length of the petiole is not significant. The width of the 
i Yes 18 omitted from the table because expressed in the shape; 1t 
“Ss variable than the length, wherefore the average length of the 
Vely narrow leaves (55.7°™) is greater than that of the rounder 
o c . . 
m3 "): I did not attempt greater accuracy of description 
Shed Margin than calling it entire, subserrate, or serrate. This 
leay # Majority of the leaves in the middle class, which includes. 
| : th a few prominent teeth irregularly scattered or only near 
Pex, or few or more numerous closely appressed teeth, or rarely 
