466 RYDBERG: PHYTOGEOGRAPHICAL NOTES 
Northern Rockies 
Claytonia megarrhiza Hulsea carnosa 
Telesonix heucheriforme Senecio Fremontit 
Oxyria digyna Alsine americana 
Selaginella densa Ribes parvulum 
Pseudopteryxia Hendersonii Polemonium viscosum 
3. ALPINE CLIFFS 
While the following plants are found elsewhere, they are char- 
acteristic of the crevices of exposed cliffs: 
*Chondrosea Aizoon Oxyria digyna 
*Leptasea austromontana Aquilegia saxtmontana 
Antiphylla oppositifolia . Polemonium pulcherrimum 
Anticlea coloradensis Polemonium delicatum 
Senecio petrocallis 
4. ALPINE MOUNTAIN SEEPS 
This formation usually is found between the mountain crests 
and the meadows, but is more moist than either. Often the 
mountain crest or mountain slope formation gradually changes 
into the meadow. This is usually the case where no melting snow- 
drift supplies the slope with more moisture throughout. the sum- 
mer; but where water is dripping or seeping down from the snow, 
along brooks, and above subterranean water courses, there is 
developed a formation, which as far as moisture is concerned 
could be classified with the wet meadow, but the ground is more 
rocky, the soil consists more exclusively of humus and most of the 
plants are different from those of the true meadow. The grasses 
and sedges are fewer both in number and in species, but otherwise 
the same as those of the meadow, although the three Poas men- 
tioned below are characteristic of these seeps, rather than of the 
meadows. Characteristic plants of these seeps are the alpine 
willows, alpine clovers, Sibbaldia procumbens, Rhodiola, species of 
Ranunculus, Senecio, Polemonium and Juncus, Taraxacum scopu- 
lorum, Mertensia alpina and its relatives, Myosotis alpestris, and, 
above all, many species of Saxifraga and its allies. 
In the northern Rockies there is found a plant association that 
may be counted here. On northern cold mountain slopes of 
