— 13— 



where only in I. papercula from the Sierra Xevadas, and speci- 

 mens of an undescribed species collected by Pringle in northern 

 Maine. 



I. Orcutti. Plant terrestrial, submersed only during the 

 growing season. Trunk slightly trilobed, 4-6cm. long by 3-5cm. 

 high, globose; leaves 6-15, 4-7C121. long, 6-7mm. broad, triangular, 

 grooved above, slightly winged at base, with two (ventral and 

 dorsal) weak bast-bundles, rarely with lateral ones also; stomata 

 none (?) ; sheaths fuscous, narrowly winged; velum entire; 

 ligula lunate or semi-circular. Microspores very small, 240 320// 

 in diameter, dark fuscous when wet, cinereous or glaucous when 

 dry, brightly polished, without crests, but the surface finely 

 pitted as if with pin-punctures, and often sparsely covered with a 

 fine, mealy-white dust. Microspores dark brown, 22-35^ long, 

 averaging 26/1 long by ij/t wide, spinulose. Growing on mesas at 

 San Diego, Cal., sent by C. R. Orcutt. Found only in "wet" 

 seasons, when there is sufficient rain to fill the low depressions on 

 top of the mesas, in which it grows. As there are often several 

 dry seasons in succession, it must have the power of lying dor- 

 mant indefinitely, if, as may well be the case, it does not make a 

 small growth in winter even when not submersed. It is not 

 unique in this respect, however, as well -ripened specimens of 

 Eatoni and Boottii have been found to retain sufficient vitality to 

 grow after being dried and kept in the herbarium six months and 

 more, while Motelay (Mon. Isoetes) states that Engelmanni has 

 been raised at the Botanic Gardens of Bordeaux from spores 

 taken from herbarium specimens. 



A few of its anatomical characters may not be without inter- 

 est to students of the genus. The rigidity of the leaf is not owing 

 to the bast-bundles, which are small, but to the epidermal cells, 

 which are large (13-17,"), with a very thick outer wall 4.4"). As 

 with all terrestrial species, the leaf cavities are very small and the 

 dissepiments correspondingly thick, from 9-12 cells on the vertical 

 to 6 on the transverse. Occasionally a bast-bundle is absent and 

 its place occupied by another layer of epidermal cells. I have 

 been unable to find stomata, but from the character of the plant 

 I think they are present, at times at least. The leaves are very 

 small and difficult to manipulate, owing to the thick dissepiments 

 and walls, which must all be removed after splitting the leaf, by- 

 scraping, before the stomata could be seen. The terrestrial spe- 

 cies heretofore found all have stomata, though less than the 

 amphibious. 



