THE RIPARIAN BOTANY OF THE LOWER SACRAMENTO. 241 
The two regions which are here contrasted lie in closest 
proximity, but the phenomena of a sudden and general 
herbaceous plant development occur in either region at 
exactly opposite seasons. The height of the herbaceous 
growth of the plains region is in March and April as that of 
the river region is in September and October. The aspect 
of the landscape in either region, however, is at such times 
decidedly vernal, belied only in the riparian area by the 
character of the plants in flower. 
On account of the water-soaked condition of the soil, the 
richness of the alluvial land, and the heat of the unclouded 
summer sun, plant life in this region is endowed with all 
the requisites for the most robust growth. Certainly this is 
the most striking feature to one who comes here in Sep- 
tember or October from the plains of the Sacramento or the 
foothills of the Coast Range. Herbaceous plants form dense 
masses through which it is difficult to force a way. Annuals 
are commonly from four to six feet in height. Certain 
species that grow in drier regions six to twelve inches high 
in favored situations and are looked upon as thrifty indi- 
viduals, here double their common stature, twice or even 
three times over. A good instanceis Boisduvalia densiflora, 
var. imbricata. As it flourishes here in the Lower Sacra- 
mento the upper virgate branches alone exceed two and one- 
half feet. Herbaceous perennials are even more luxuriant 
in their growth. Such attain in one short season a height of 
sixteen or eighteen feet. Excellent evidence of this sort of 
vigor is furnished by Helianthus Californicus and Urtica 
holosericea. Other plants of the plains and foothills whose 
height is set down in feet or inches may here be measured 
in yards. 
The distribution of the larger wooded growth is only a less 
siriking feature than the luxuriance of the herbaceous plants, 
Throughout all this region, the rivers, cross-channels, and 
sloughs are edged by a fringe of trees. This growth is 
supported by the natural levees which bound the water- 
courses and form a rim to the islands. The boat 
