1906] SHANTZ—VEGETATION OF THE MESA 189 
Gutierrezia Sarothrae, Artemisia canadensis, and Tetraneuris glabriu- 
scula, Thisis probably the best example of primary succession found 
by the writer. The absence of ruderal species is especially noticeable. 
On the mesa the Andropogon scoparius consocies seems to be 
most primitive. In places not yet covered with vegetation, where 
the alluvium is nearest what it seems to have been originally, this 
grass is most abundant and together with Eviocoma cuspidata is 
the first to disappear in passing from this exceedingly open association 
to the more stable or closed Bouteloua formation. Eriognum alatum, 
E. Jamesii, Tetraneuris glabriuscula, and Machaeranthera cicho- 
raced are generally present; but since they extend into the true 
Bouteloua formation they are probably not as much a part of the 
primitive association as the plants mentioned above. 
The lime ridge vegetation is probably primitive, as shown by the 
following quadrat: 
Lesquerella alpina. . . . . s2  Ofreocaryathyrsiflora . . . . 3 
Gutierrezia Sarothrae . 2. 5  Gaura coccinea . $f tahoe 
Lithospermum linearis . 4  Machaeranthera cicluccaton eee 
Total sites covered, 5 to6 %. 
At some distance from this, a quadrat shows the sn do 
Lesquerellaalping. . |. 31 Eriogonum Jamesii 3 
Grindelia squarrosa - . . 4 Tg Boebera papposa- 3 
Hedeoma nana ' 13 Lithospermum linearis. : 
Gaura coccinea. 62 leo BS pelnola 2 raeaie J 
Bouteloua ligostachya. oe Gos Ge a 2 
Aristida lon ngiseta wo Vo a erat teres I 
Stipa Vase aeyh 
: > : ; 3 
Total surface covered, 7 to 8%. 
The entrance of Bouteloua is already noted, as is Aristida long- 
isela. A more distant point will show the following a 
Bouteloua Oligostachya .. .. . $4 Lithospermum linearis 6 
theropogon curtipendulus . . 28 Aristida longiseta 3 
Grindelia squarrosa 5 wt; . 16  Eriogonum Jamesii 4 
Boebera papposa 57. Pentstemon angustifolis I 
Malvastrum coccineum 7 Salvia linearis . _ 
Lesquerella MDA Ge ee Stipa Vaseyi * 
Helianthus annuus... (|, 4.48 Salsa. Trae : 
Gutierrezia Sarothrae . . . 13 Artemisia frigida 3 
Chenopodium leptophyllum . . to  Evolvulus pilosa . 
Total surface covered, 18 to 20%. 
