44 BOTANICAL GAZETTE [JULY 
very important; Andropogon furcatus, Yucca glauca, Erigeron 
pumilus, and E. canus are often present. 
The physical conditions of this consocies are not essentially 
different from those of the typical formation, except that the looser, 
gravelly soil contains less water. It is the most xerophytic of all 
the consocies. The following crest quadrat from the south part 
of the Mesa also illustrates this consocies. 
Bouteloua hirsuta......... 45°. 30%). Artemisia frigila 23 cee Pe 2 
Bouteloua ee 34. 3% Senecio oblanceolatus............. 2 
Aristida longiseta......... S 36% 5 Gaurd cottifies: -.cF  a I 
Atheropogon aes 30 <..5% © -Qreocarya: thyrsiflora: 00 Se 6. Tr 
Gutierrezia Sarothrae..... 4 Echinocereus viridiflorus........... 1 
Senecio spartioides........ 3 Lecanora subfusca ailophana®: cere 20 
oo. angustifolius 3 Total a COVETEN es ok 8 23% 
usts—a remnant of ie more primitive lichen form 
eat content: vernal period 6-10%; aestival re ; autumnal 2.5-4%- 
Soil, very coarse gravelly loam. 
Societies of the Bouteloua hirsuta consocies: Pentstemon secundi- 
florus society found on crests of the north or east part of the Mesa. 
The following quadrat is typical: 
Pentstemon. secundi- Evolvulus: pilosé..i.c630 6s 0: 2288 7 
florus, (81 in bloom).....141 Sideranthus spinulosus..........-- 6 
Artemisia frigida.......... 7%  Echinocereus viridiflorus.........-- a 
Bouteloua hirsuta.......... 65 pattie Was es ek ae 4 
squerella montana (seed- Poruiaca oleracea... 5.6 cies I 
ng oe a 40 Total surface covered.........-- 24% 
Boebera 
Water content: vernal period 4.5-9%; aestival 2. 5-4-5%; autumnal 1.57 
2.5%. Soil, coarse gravelly loam. 
Pentstemon angustijolius society—While Pentstemon angusti- 
jolius does not form so dense an association as P. secundiflorus, the — 
spikes are much larger, and it is therefore very prominent in certain — 
areas. The following quadrat is typical: 
Bouteloua hirsuta.......... 17 20% Artemisia canadensis..........--- 2 
Pentstemon angustifolius... 14 (5%) Eriogonum Jamesii...........--- ta 
Aristida longiseta.......... 1%  Thelesperma gracile...........--- I ‘ 
Chrysopsis villosa.......... 8 Boehers. paptioes <: 55.44 3.06 
Allionia linearis........... 5 Euphorbia stictos 
Echinocereus viridiflorus.... 2 
Gutierrezia Sarothrae 2 
ee eee 
otal surface covered 
