44 BULLETIN 791, U. S. DEPARTMENT OP AGRICULTURE. 
SUMMARY OF THE FOXGLOVE-SWEET-SAGE- YARROW CONSOCIATION. 
The foxglove-sweet-sage-yarrow cover, less specifically known as 
the second or late weed stage, is the initial type in the retrogressive 
succession of the porcupine-grass-yellow-brush consociation. The 
more characteristic plants of this weed stage generally are compara- 
tively aggressive where the conditions of growth are reasonably 
favorable. A rather large number of species are associated with the 
foxglove-sweet-sage-yarrow type species, though they seldom occur 
as dominants. By far the greater number of the secondary plants 
are nongrasslike. A few grasses are present, however, among which 
large mountain brome grass is by far the most important. 
The type species and several of the secondary plants reproduce 
both vegetatively and by seed. In several species vegetative repro- 
duction is so active as to produce a loose matlike ground surface. 
Most of the plants are shallow-rooted. \Yhen the soil conditions 
become unfavorable for the maintenance of the foxglove-sweet-sage- 
yarrow cover an aggressive succession of shallow-rooted, relatively 
short-lived perennial plants in association with a number of annual 
species usually takes place. In instances of severe soil depletion 
annual species invariably predominate. 
Low pea vine, evening primrose, false cymopterus, Mexican dock, 
and tongue-leaved violet are the most reliable and characteristic ini- 
tial indicators of the destruction of the more stable second-weed-stage 
cover. If the disturbing factor continues to operate, these rather 
short-lived perennials are sooner or later superseded by annual plants. 
Much less dry matter and notably less palatable feed are produced 
on the late-weed-stage type than on the wheat-grass or on the porcu- 
pine-grass-yellow-brush consociations. The profusion of weed or 
nongrasslike plants and the small amount of grass forage produced 
makes the second- weed-stage cover better suited for the grazing of 
sheep than for cattle and horses. Owing to the fact that sheep graze 
nongrasslike plants with considerably greater avidity than cattle and 
horses, the foxglove-sweet-sage-yarrow consociation can be fully 
utilized by the grazing of sheep alone. Sheep, however, will not 
show as much progress on the second-weed-stage consociation as on 
the porcupine-grass-yellow-brush consociation. The gains may be 
fairly large but the fat is not of a solid character. Cattle and horses 
do poorly on the late weed type. As a rule, they little more than main- 
tain their weight. 
THE RUDERAL-EARLY-WEED CONSOCIATION. 
Soils which were formerly rich but which have been so seriously 
impaired that their fertility is similar to that of relatively new soils 
recently invaded by herbaceous plants, support virtually the same 
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