VOL. Iv. | Colorado Plants. 5 
the coat, which is less deeply pitted; the seeds are larger. The 
pods of A. hispida are ovate, and when they dehisce the seg- 
ments are acuminate. In A. platyceras the pods are veiny and 
the segments acute. I have seen no intermediate forms which 
might connect these two that seem so different. 
ERYSIMUM ASPERUM DC. ‘This widely distributed speciés, as 
found on the plains, is low and stout, with pods often four inches 
long, numerous and perpendicular to the stem. The pods are 
stiff, and, projecting as they do, remind one of the spears of a 
Macedonian phalanx. The flowers are yellow. The variety at 
Silverton, in the San Juan Mountains, has the color of the flowers 
from pale yellow, almost white, to orange on the one hand, and 
through shades of pink and crimson to purple on the other. 
These different shades were found in one patch and seemed to 
indicate that the common yellow form had become mixed with a 
purple variety. The mountain form is more slender than the 
prairie plant, and the pods are ascending. 
ArABIs Horspaiiit Hornem. This is one of the most 
puzzling of the western Cruciferze because of its great variety of 
forms. If there are any plants of 4. Holbellii with one row of 
seeds in each cell, wherein does it differ from A. canescens, which 
also has stellate pubescence and deflexed pods? The division, if 
A. canescens is a good species, should be thus: Pods deflexed 
or spreading, seeds in one row, A. canescens; seeds in two rows, 
A. Holbelliz. If pods containing both one and two rows of seeds 
are found on the same plant of 4. Holbelliz, then A. canescens 
ought to be included under 4. Holbeliii. Including under 4. 
Hfolbellii all the forms that are perennial and have pods deflexed 
or spreading, with two rows of seeds in each cell and pubescence 
generally stellate, the following forms should be described in 
order to make the species better understood: 
1. From Mancos, Colo. Stem simple, stout, tall, thickly 
clothed at base with white branching hairs, but not stellate, 
above glabrous and glaucous; radical leaves from spatulate to 
oblanceolate, sparingly dentate or entire; cauline leaves sagittate- 
clasping, pedicels spreading upwards and outwards, pods deflexed 
or horizontal, glabrous; winged seeds, two rows in each cell, 
petals twice as long as the stamens, erect. 
