1922] 



PFEIFFER — MONOGRAPH OF THE ISOETACEAE 133 



indistinct papillae or almost smooth, glistening; microspores 

 21-27 u, rarely 29 u, in length, chiefly spinulose, sometimes 



smooth. 



Distribution: California, Lower California. 



Specimens examined : 



California: mesas in low depressions, San Diego, 7 June, 1884, 



Orcutt 1242 (Mo. Bot. Gard. Herb., Gray Herb., and U. S. 

 Nat. Herb.), type; 3 mi. northeast of Clovis, Fresno Co., 16 

 February, 1902, Mr. & Mrs. C. H. Thompson (Mo. Bot, 



Gard. Herb.) ; meadow, Soquel Point, Santa Cruz, 10 and 

 29 April, 1900, C. H. Thompson (Mo. Bot. Gard. Herb.) ; 

 Soquel Point near Capitola, Santa Cruz Co., 6 March, 1901, 

 Mrs. C. H. Thompson (Mo. Bot. Gard. Herb.) ; El Cajon, 

 April, 1895, Brandegee (Mo. Bot. Gard. Herb.) ; 5 mi. west 

 of Stanford University, near Los Francos Creek, 13 April, 

 1903, Thompson (Mo. Bot. Gard. Herb.); near Upland, 

 growing in desiccating pools on clay mesa, 8 March, 1917, 

 Ivan Johnson (U. S. Nat. Herb.) ; mesas, San Diego Co., 14 

 May, 1903, Orcutt (U. S. Nat. Herb.) ; in "Hog Wallows, 

 dry as early as 10 March, usually wet until May 1," 1889, 

 Curran (N. Y. Bot. Gard. Herb.); Antioch, Contra Costa 

 Co., 7 April, 1895, Burtt Davy (N. Y. Bot. Gard. Herb.). 



Lower California: near Santo Tomas, 12 April, 1886, Orcutt (Mo. 



Bot. Gard. Herb.). 



This form differs from /. Nuttallii A. Br. chiefly in the smaller 

 plants, both in length and number of leaves, and in the smaller 

 size of the spores. The largest megaspores of /. Orcuttii are in 

 the range of the smallest of /. Nuttallii. There is also a difference 

 in the peripheral strands in that /. Nuttallii usually has three, 

 of which the weakest or dorsal sometimes fails to develop. In 

 /. Orcuttii, no such strands appear in the various leaves I have 

 examined, though A. A. Eaton reported the presence of two 

 weak groups of cells, a dorsal and ventral. Brandegee's ma- 

 terial from San Diego combines megaspores with prominent 

 markings that plainly fall in the range of /. Nuttallii (364-448 \x), 

 sporangia larger than those of /. Orcuttii, but leaves the length 

 of the latter (2.5-3 cm.), with no peripheral strands. Since it is 

 believed that the leaf characters are more subject to ecological 



factors 



and this specimen 



