■ 'SELAGINKI.LACRAE 25 



group With bilobed trunks, are all submerged, with quadrangular leaves and 

 an incomplete velum. 



Leaves acute, not long-pointed; stomata absent' , . . . , 1, I. lacustris._ 

 Leaves with a long fine point jstomata present 2. 1. Bolanderi, 



1. Isoetes lacustris L. Sp. PI. 1100. 1753. Leaves stout, rather rigid, 

 acute but scarcely tapering, dark or olive-green, 10-25 in number, 5-15 cm. 

 long, with no stomata: sporangium orbicular to broadly elliptical, not spotted, 

 with a rather narrow velum; megaspores 0.5-0.8 mm. in diameter, marked 

 all over with distinct or somewhat confluent crests: microspores smooth, 

 0.035-0.046 mm. in the longer diameter. — Generally distributed through- 

 out northern America. 



la. Isoetes lacustris paupercula Engehn. Trans. St. Louis, Acad. 4: 377. 

 1882. Leaves fewer (10-18), thinner, shorter: spores smaller; megaspores 

 0.50-0.66 mm. in diajneter; microspores somewhat granulated, 0.026-0.036 

 mm. long. — Grand Lake, Middle Park, Colorado, and near Mt. Shasta, Cali- 

 fornia. 



2. Isoetes Bolanderi Engehn. Am. Nat. 8; 214. 1874. Leaves erect, soft, 

 bright green, tapering to a fine point, 5-25 in number, 5-10 cm. long, generally 

 not many stomata: sporangium broadly oblong, mostly without spots, with 

 a narrow velum; megaspores 0.30-0.40 mm. thick, marked with minute low- 

 tubercles or warts; microspores 0.026-0.031 mm. long, generally spinulose, 

 rather smooth. — In ponds and shallow lakes in the Rocky Mountains, Sierra 

 Nevada of California, and Cascades. 



6. LYCOPODIACEAE Mich.?. Club Moss Family. 



Moss-like plants, with small leaves imbricated in 4-many rows on the 

 pinnately or dichotomously branching stems, and (in ours) with reniform 

 1-celled sporstngia in the axils of bracts, forming stalked or sessile spikes. 

 Spores all ahke. Prothalha subterranean. 



1. LYCOPODIUM L. Club Moss. Ground Pine 



Characters those of the farnily. In ours thei, leaves (bracts) of the spike are 

 yellowish, ovate or heart-shaped, very difierent from the other leaves. 



1. Lycopodimn annotinum L. Sp. PL 1103. 1753. Stems prostrate and 

 creeping, 3-10 cm. , long; the ascending branches similar, djchotomous, 10- 

 15 cm. high: leaves in several ranks, equal, spreading, rigid, lanceolate, 

 pointed, serrulate, 4-5 mm. long: spikes solitary at the ends of leafy branches. 

 — From Colorado to Washington, northward and eastward across the conti- 

 nent. 



7. SELAGINELLACEAE Underw. 



Moss-like terrestrial annual or perennial plants with slender branching 

 stems and small leaves arranged in 4 or several ranks. Sporangia solitary, 

 in the axils of the leaves of the somewhat quadrangular spike, minute, sub- 

 globose; some containing 4 megaspores; others numerous microspores. From 

 each of these spores are developed the prothallia bearing archegonia and 

 antheridia respectively. 



1. SELAGINELLA Beauv. 



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

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



