VEGETATION OF UNDRAINED DEPRESSIONS ON 

 THE SACRAMENTO PLAINS 



Francis R amaley 

 (with one figure) 



The observations here recorded were made in 191 7 from March 

 to May inclusive, chiefly in the neighborhood of Sacramento, 

 California. Study, however, was extended in all directions for 

 distances of 20 miles or more, and even to Chico, 90 miles north, 

 and to Stockton, 40 miles south. 



Most of the area is exceedingly flat and low. The city of 

 Sacramento itself is at an altitude of 30 ft. above sea-level. Except 

 to the east, in the Sierra foothills, there is scarcely a rise of 100 ft. 

 within 25 miles. Soils are largely sand, sandy loam, sandy clay, 

 and clay loam. Any fine grained soil which retains water is 

 popularly known as "adobe," the term not being confined to clay. 



The numerous shallow depressions' of the Sacramento plains^ 

 have arisen from the leaching out of limestone masses. They 

 are of various extent, some only a few square meters in area and 

 others 100 m. or more across, with a depth of a few centimeters 

 or decimeters. The soil is very fine grained and holds water for 

 an astonishingly long time after rains, often for one or two weeks. 

 During the rainy period of winter these low places may be con- 

 stantly full of water. Even with the lessened rainfall of early 

 spring there is likely to be standing water during much of the 

 month of March. Besides these vernal pools there are many 

 shallow "draws, " or ravines, having a vegetation cover which bears 

 a resemblance to that of the undrained depressions. As would be 

 expected, however, they have many more species of plants because 



'These depressions could hardly escape the notice of botanists. Mention of 

 their flora is made in the preface (p. 5) of Jepson's "Flora of Middle Western Cali- 

 fornia," ed. 2. 1911. 



^The term "Sacramento plains" is well established in botanical and popular 

 writings, but these are not "plains" in the usual botanical sense. The vegetation is 

 rather that of a vernal meadow or vernal prairie. During the growing period of 

 March, April, and May the soil moisture is sufficient for the support of true mesophytic 

 species; witness the abundance of European weeds. 



Botanical Gazette, vol. 68] [380 



