198 BOTANICAL GAZETTE [SEPTEMBER 
Solanum triflorum, Senecio oblanceolatus, and S. spartioides; also a 
very few young plants of Yucca glauca, Argemone intermedia, 
Carduus undulatus, and Tetraneuris glabriuscula. 
The usual flora on the hills of the prairie dog is Anogra coronopi- 
jolia, Malvastrum coccineum, Munroa squarrosa, Amaranthus 
blitoides, Picradeniopsis oppositifolia, Boebera papposa, and Arle- 
misia frigida. Muhlenbergia~ gracillima is the most effective in 
reclaiming the old deserted hills. In fact, in looking over a deserted 
dog town the location of the old dog hills can be determined at once 
from the fact that although the surrounding vegetation is dominated 
by Bouteloua oligostachya, the location of the old hills is marked by 
a community of Muhlenbergia gracillima. 
Near Pring, Colo., an abandoned field showed the first year 
Helianthus petiolaris, with a less amount of Boebera papposd, 
Malvastrum coccineum, Solanum rostratum, Lappula occidentalis, 
Verbena bracteosa, and a very few plants of Artemisa frigida, 
Atheropogon curtipendulus, Schedonnardus paniculatus, Carduus 
undulatus, and Eriogonum annuum. Here are found three very 
distinct sets in the succession. First, annual species, followed by 4 
group of ruderal species, and this in turn by perennials from the 
Bouteloua formation. In another place Thelesperma intermedium 
was the first species to enter. Near Falcon, Col., an abandoned 
field showed after two years Helianthus petiolaris and also Munroa 
squarrosa, Lappula occidentalis, Chaetochloa viridis, Plantage 
Purshii, Amaranthus retroflecus, and Ptiloria ramosa. In some 
places Bouteloua oligostachya was entering. Another field which 
had been abandoned for about eight years showed 5S porobolus 
cryptandrus, Aristida longiseta, Schedonnardus paniculatus, Cenchrus 
tribuloides, as well as Senecio oblanceolatus and Munroa squarros’s 
a few annuals, the more important of which were H elianthus 
petiolaris, Verbena bracteosa, and Cryptanthe ramosissima. Into this 
area Bouteloua oligostachya was pushing its way and had in places 
near the edge of the field almost replaced the other species. 
Several miles west and south of Fountain, Col., a most interesting 
stage of succession is shown. The surrounding vegetation is of the 
Bouteloua oligostachya consocies with very few primary and secondary 
species. An area which had been broken and abandoned showed 
