1900] ROCKY MOUNTAIN HERBARIUM Ig! 
bases: crown leaves less crowded, some of them sparsely den- 
tate; the stem leaves oblong to ovate, the larger ones dentate: 
fruiting racemes shorter, the pods broader, scarcely arcuate, 
divaricate-ascending ; the flowers larger as are also the seeds. 
No other Arabis is known to me that has the habit of this. A single plant 
sometimes has fifty or more assurgent stems and forms a hemispherical mat 
several decimeters in diameter. In this respect the preceding species most 
nearly approaches it. The two were found in the same locality, but they are 
at once recognized as different. 
The type is no. 5681, Undine falls, July 6, 1899. 
Arabis lignipes.— Short-lived perennial, simple-stemmed or 
more rarely with two or three stems from the summit of the tap 
root; the woody base of the stem persistent, apparently of as 
many internodes as the plant is years old, leafless, more or less 
Covered with the old petioles ; the internodes variable, usually 
only 1-3" long, the whole forming a naked woody foot sur- 
mounted by the crown of rosulate leaves at the base of the 
herbaceous part of the stem; herbaceous stems ultimately 3-5°™ 
high, begirning to blossom when quite low, erect, finely stellate- 
pubescent below, glabrous upward, becoming smooth throughout 
in age: the rosulate leaves small and crowded, entire, minutely 
but densely stellate pubescent, narrowly oblanceolate, tapering 
to a short petiole, r—2-™ long ; the stem leaves numerous, sessile, 
almost linear, tapering to an acute apex from an auricular sagit- 
tate base, slightly longer than the rosulate leaves: raceme 
Crowded in anthesis, open in fruit : pedicels sharply deflexed 
€xcept in the youngest buds, at first minutely pubescent as are 
also the sepals, 5-7™™ long : petals purplish or sometimes white, 
_"atrowly spatulate, 5-6" long, nearly twice as long as the 
Sepals : pod pendent, straight or curved, smooth, 1-nerved, 
cs long, about 2™ broad: seeds in one row, broadly oval, 
meatcely wing-margined, about 1™™ long. : | 
This finds its nearest ally in 4. Holboe//ii Hornem., from which its naked 
oody foot, its invariably simple stems, its smaller entire leaves, and its per- 
character separates it. 
The following collections of it were secured on dry, sandy or stony bottom 
lands in Yellowstone park: no. 5503 and 5505, Madison river, June 23, Te 
n0. 583, Glen creek, June 30, 1900. 
