33 



in the species. Later material from 

 several localities in Central Cal., show 

 that it grades almost imperceptibly in- 

 to Howelli, on one hand, and the type 

 and Var. pallida on the other, so with 

 the mostly unripe material furnished it 

 is hard to draw the Ime." A. A. Eaton. 



ISOKTES OKCUTTil A. A. Eaton. 



"Plant terrestrial, submerged only 

 during the growing season. Trunk 

 slightly trilobed, 4-6 cm long by 3-5 

 cm high, globose; leaves 6-15, 4-7 cm 

 long, 6-7 mm broad, triangular, grooved 

 above, slightly winged at base, witn 

 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. Macrospores 

 very small, 240-320 u in diameter dark 

 fulvous when wet, cinereous or glau- 

 cous when dry, brightly polished, with- 

 out crests, but the surface finely pit- 

 ted as if with pin-punctures, and orteu 

 sparsely covered with a fine scaly- 

 white dust. Microspores dark brown, 

 22-35 u long, averaging 26 u long by IT 

 u 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 mesus, 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 we.l 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 Bootti have been found to retain 

 sufficient vitality to grow after being 

 dried and kept in the herbarium six 

 months or more, while Motelay (Mon. 

 Isoetes) states that Engelmanni has 

 been raised at the Botanic Gardens of 

 Bordeaux from spores taken from her- 

 barium specimens. 



"A few of its anatomical characters 

 r^.ay not be without interest to stu- 

 dents of the genus. The rigidity of the 

 leaves is not owing to the bast-bun- 

 dles, which are small, but to the epi- 

 dermal cells, which are large (13-17 u). 

 v.ith a very thick outer wall (4.4 u). 

 As with all terrestrial species, the leaf 

 cavities are very small and the dissep- 



34 



inents correspondingly thick, from 9-12 

 cells on the vertical to 6 on the trans- 

 verse, Occasionally a bast-bundle is 

 absent and its place occupied by an- 

 other layer of epidermal cells. 1 have 

 teen 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 dissep- 

 inents and walls, which must be re- 

 moved after splitting the leaf by scrap- 

 ing, before the stomata could be seen. 

 The terrestrial species heretofore 

 found all have stomata, though fewer 

 than the amphibious. 



"This is the only North American 

 sj-ecies with ashy spores, though one 

 black or dark brown spored species, 

 Melanospora. is found. Colored spores 

 are found on several widely separated 

 species. Tasmania gives Gunnii, Stu- 

 arti, and Hookeri with glaucous or 

 ashy spores; Australia gives Muellerl 

 with ashy and tripus with fuscous 

 spores. From South America we have 

 Gardneriana with blackish spores, and 

 from Central Africa Nigritana and 

 Welwitschii with glaucous spores. Sev- 

 eral other species have spores that are 

 not chalk-white, the usual color. 



"In all cases the color seems to be a 

 pigment secreted in the spore itself, 

 the enveloping silica having the usual 

 white color, and all elevations have a 

 chalky whiteness 



"When the deposit of silica is thin 

 the spores are dark brown, and ashy 

 when it is thicker." A. A. Eaton, Fern 

 bulletin 8:13 (1900). 



* Epidermis mounted in glycerine and 

 allowed to stand till well cleared show 

 many stomata. A. A. Eaton (17 JI 

 1903). 



** Since seen from Clovis and Pine 

 Ridge, Fresno Co., Cal.. C. H. Thomp- 

 son. Soquel Point, Thompson. Santa 

 Maria, Lower Cal.. C. R. Orcutt. 



HrSACKTA R1GIDA B h. 



Stems rigid, fiexuous, with long in- 

 ternodes, herbage silky-canescent: 

 leaflets 3-5, cuneate-oblor.g or obovate, 

 crowded -on a very short rachis, whole 

 leaf subse^si!e: peduncles elongated, 

 rigid. 1-3-fl'd; supporting a small 1-3- 

 folio'ate bract: corolla % in. long; ca- 

 lyx-tube cylindrical, 3 lines long; sub- 



