58 BULLETIX 791, U. S. DEPARTMENT OF AGRICULTURE. 
from the time of the waning of the early-weed stage to the passing of 
the late-weed stage; therefore, on the higher ecological types, an in- 
crease in the abundance of larkspur may be declared a reliable 
indicator of overgrazing. 
Generally low larkspur is most conspicuous early in the develop- 
ment of the second-weed stage. Accordingly, on cattle range the 
heaviest losses from poisoning by low larkspur are apt to occur where 
the lands have been depleted so seriously that the vegetation is in the 
second-weed stage or in the first and second mixed-weed stage. 
BED GROUNDS. 
Although some variation is found in the vegetation of different 
bed grounds and adjacent lands of the region, depending chiefly on 
the character of the soil and the topographic features, the predomi- 
nating species are generally the same where the extent of the deple- 
tion of the soil is the same. 
On long-used bed grounds, where the adjacent cover is more or 
less intact, various distinct vegetative stages may commonly be dis- 
tinguished, radiating from the bed ground proper. This is exempli- 
fied in the bed ground shown in figure 24. 1 
The main part of the bed ground (zone 1) is practically circular 
and covers 22 acres. Owing to the heavy use made of the bed ground 
each year, not a vestige of the original wheat-grass vegetation re- 
mains: indeed, even the most aggressive annual plants are for the 
most part lacking. 
Adjacent to the bed ground proper is an irregular zone of about 85 
acres. Here the colonization is composed solely of plants of the first 
or early weed stage. The plants are widely scattered (the density be- 
ing estimated at 0.05 on a basis of ten-tenths representing full cover) 
and are distinctly lacking in luxuriance of growth. The species pre- 
dominating in 1917, named in the order of abundance, were Douglas 
knotweed. Tolmie's orthocarpus, tansy mustard, tarweed, goosefoot, 
and androsace. Much less conspicuous were the following species: 
knotweed (Polygonum aviculare), monolepis, peppergrass, and 
slender-leaved collomia. 2 As already indicated, this type of. cover 
afforded practically no grazing for any class of stock. 
Zone 3 comprises approximately 215 acres, and consists of a weed 
cover of the early and late stages, with the early-stage species dis- 
tinctly predominating. An occasional grass specimen is also seen. 
Here the density of the cover is estimated at 0.15, or three times that 
of the pure early- weed stage adjacent to the bed ground. The pre- 
1 The bed ground here represented has been used annually for several successive years 
by a band of about 1,400 ewes and their lambs. As a rule, the forage cropped in con- 
junction with the use of this camp has been grazed during the main growing season. 
- Slender-leaved collomia is often among the first to colonize abandoned bed grounds and 
sometimes is a predominating species. 
