SELAGINELL^ 435 



1. ISOETES, L. Qdillwort. 



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

 mann in Trans. St. Louis Acad. iv. 358. Our species {a.s reported at present) 

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

 lar leaves and an incomplete velum. 



1. I. lacUStris, L. Leaves stont, mt/ier riijld, acute hut scarcehi taperimj 

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

 sporangium orbicular to broadly elliptical, nut spotted, with a rather narrow 

 velum; macrospores 0.50 to 0.80 mniA in diameter, marked all over with distinct 

 or someichat confluent crests; microspores smooth, 0.035 to 0.046 mm. in the lomjer 

 diameter. — Generally distributed throughout Northern America and New 

 England. 



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

 3 inciies) : 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 indies 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 jNIountains ( 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, mostlg irithout spots, with a narrow velum : macro- 

 spores 0.30 to 0.40 :nm. thick, marked with minute loiv tubercles or warts ; micro- 

 spores 0.026 to 0.031 mm. long, generalli/ spinnlose, rarely smooth. — Am. Nat. 

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

 of California, and Cascades. 



Order 92. SELAGIIVELI.^, 



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

 ranged in 4 or several rankit sporangia minute, suhglohose ; some 

 containing usually 4 globose macrospores ; others (smaller and more 

 abundant) filled ^yith numerous microspores. 



1. SELAGINELLA, Beamois. 



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

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



> The milliuietcr is verj' nearly half a Una 



