42 BOTANICAL GAZETTE [yuLy 
Bouteloua oligostachya ....134 22% Senecio spartioides............... 4 
Muhlenbergia ee ee 5 7%  Sideranthus spinulosus........... 12 
Artemisia frigida.......... GO, Poevers. PADDOGA. os. ee ec 81 
Senecio oblanceolatus...... 9 PrANCAGD PUM. 8.2. 25 cy eo ee 2 
Aristida longiseta.......... I Polygonum aviculare............. I 
Astragalus Shortianus...... I Townsendia exscapa............- I 
Schedonnardus paniculatus. 1 Cyn. ‘argentewm: 24. 30>. Sens 
Chrysopsis villosa.......... Total surface worverell. ...42% 
Water content: vernal ne 8-13%; aestival 6-8%; sgucinid 5-6%. 
Soil, gravelly loam. 
The most important difference in the habitat is in water content, 
the other factors being seed the same as given under the aspects 
of the formation. 
The following quadrats are also typical of the Bouteloua oligos- 
tachya consocies, but represent this consocies as modified by the 
occurrence within it of societies. 
Bouteloua oligostachya ......... 47% Euphorbia stictospora............ 9 
Artemisia frigida............... 45576. BOCRETA. DADROSE 5 oy aes sone 5 996 
nogra coronopifolia............. ot: Abgpre albicailis e606. 9-36 425 2 
Senecio oblanceolatus............ Total surface covered..........- 56% 
Water content: vernal period se. aestival 46%; autumnal 3-4%. . 
Soil, fine gravelly loam. : 
A quadrat within a Gutierrezia Sarothrae society: 
Bouteloua oligostachya..... 168 Eriogonum effusum.............. 5 
Gutierrezia Sarothrae ...... 22 PMIGUETS, DRTIOONN <6 < ooo) ccs ches 5 
eee 10 Malvastrum coccineum..........- © 
Water content: vernal period 4 5%; aestival 4-7%; autumnal 2-4%- 
Soil, coarse gravelly loam mixed with lime. 
The following quadrat will serve to illustrate a portion interme- 
diate between the Bouteloua oligostachya consocies and the Muhlen- 
bergia gracillima consocies. 
Muhlenbergia gracillima .. 20 33% Boebera peIpea. soa es 36 
Bouteloua oligostachya..... 24 12% Atheropogon curtipendulus.......- I 
Sideranthus spinulosus..... 3 Aliishia linearis.) 2504 os I 
vastrum coccineum..... 5 Echinocereus viridiflorus........-- I 
Artemisia a i 2 To = surface covered nage eee et ye 
