THE RIPARIAN BOTANY OF THE LOWER SACRAMENTO. 239 
Its course for one hundred and fifty miles from its mouth at 
the head of Suisun Bay is bounded by brackish marshes 
which stretch away from the river ten to fifteen miles on 
either hand. These marshes are given a decided, although 
not local, character by the prevalence of one or two species 
of bog-rush or “tule,” and are commonly referred to as “tule 
lands,” a Californian provincialism adapted from one of the 
Spanish-American dialects. Near the mouth of the river, 
and for forty miles above as the waters run, are many islands, 
some small and others of considerable area. These have been 
formed by the delta-making process, by changes in the main 
river channel, and by ramifications of the tide-water sloughs 
which often reach far into the marsh country. 
The expression “Lower Sacramento” was first used as the 
geographical designation of that portion of the Sacramento 
River lying below the junction of its first principal tributary, 
the American. It is now applied to the Lower Sacramento 
Valley as a whole, and having this force it has been very fre- 
quently used in the latest botanical literature of California. 
The above title indicates the limits of the region under 
consideration. This paper has reference to the islands of the 
Lower Sacramento and to the overflowed lands bounding the 
river channel as far as the American. The principal islands 
are Brannan, Andrus, Tyler, Grand and Ryer. Grand Island, 
the largest, is some twelve miles long and three to five miles 
wide. Towards the mouth of the American the marsh strip 
on the eastern side of the river becomes quite narrow; on the 
western side the tule lands northward from Cache Slough 
are more extensive and extend untraversed by any water 
course to and beyond Putah Creek, a stream from the Coast 
Range vanishing in the marshes a little below the mouth of 
the American. 
Along the new and old river channels the deposition of 
sediment has built up natural levees. The river banks are, 
therefore, highest, and back of them lie the brackish marshes, 
reaching to the edges of the plains. These natural levees | 
form, also, a rim to the islands, and slope back to the cen- 
