SELAGINELL^E. 435 



1. ISOETES, L. QUILLWORT. 



Characters those of the order. For an elaboration of the genus see Engel- 

 mann in Trans. St. Louis Acad. iv. 358. Our species (as reported at present) 

 belong to the group with bilobed trunks, are all submerged, with quadrangu- 

 lar leaves and an incomplete velum. 



1. I. lacustris, L. Leaves stout, rather rigid, acute but scarcely tapering 

 dark or olive-green, 10 to 25 in number, 2 to 6 inches long, with no stomata: 

 sporangium orbicular to broadly elliptical, not spotted, with a rather narrow 

 velum ; macrospores 0.50 to 0.80 mm. 1 in diameter, marked all over with distinct 

 or somewhat confluent crests; microspores smooth, 0.035 to 0.046 mm. in the longer 

 diameter. Generally distributed throughout Northern America and New 

 England. 



Var. paupercula, Eng. Leaves fewer (10 to 18), thinner, shorter (2 to 

 3 inches): spores smaller; macrospores 0.50 to 0.66 mm. in diameter; mi- 

 crospores somewhat granulated, 0026 to 0.036 mm. long. Trans. St. Louis 

 Acad. iv. 377. Grand Lake, Middle Park, Colorado (Engelmann), and near 

 Mt. Shasta, California (Pringle}. 



2. I. echinospora, Durieu, var. Braunii, Engelm. Leaves soft and 

 tapering, green or reddish green, erect or spreading, 13 to 15 in number, 3 to 

 6 inches long, generally with a few stomata towards the tip : sporangium as in 

 the last, but spotted and generally \ or even covered by a broad velum ; 

 macrospores 0.40 to 0.50 mm. thick, covered with broad retuse spinules, sometimes 

 somewhat confluent and then dentate or incised at tip ; microspores 0.026 to 

 0.030 mm. long, smooth. Gray, Manual, 676. Lake at the head of Bear River, 

 Uinta Mountains ( Watson). The most common species eastward, but re- 

 ported only from the one station within our range. Apparently replaced 

 with us by the following. 



3. I. Bolanderi, Engelm. Leaves erect, soft, bright green, tapering to a 

 fine point, 5 to 25 in number, 2 to 4^ inches long, generally not many stomata : 

 sporangium broadly oblong, mostly without spots, with a narrow velum ; macro- 

 spores 0.30 to 0.40 mm. thick, marked with minute low tubercles or warts ; micro- 

 spores 0.026 to 0.031 mm. long, generally spinulose, rarely smooth. Am. Nat. 

 viii. 214. In ponds and shallow lakes in the Rocky Mountains, Sierra Nevada 

 of California, and Cascades. 



ORDER 92. ELAGINELL,B. 



Moss-like plants with slender branching stems and small leaves ar- 

 ranged in 4 or several ranks : sporangia minute, subglobose ; some 

 containing usually 4 globose macrospores ; others (smaller and more 

 abundant) filled with numerous microspores. 



1. SELAGINELLA, Beauvois. 



Characters those of the order. In ours the leaves are all alike arranged in 

 many ranks, those of the fruiting spikes 4-ranked. 



i The millimeter is very nearly half a lino. 



