130 OUR NATIVE FERNS AND THEIR ALLIES. 



The order Lycopodiales contains three families which may 

 be distinguished as follows : 



1. Spores of one sort . . Family \. LYCOPODlACEiE, p. 130. 

 Spores of two sorts, powdery microspores and larger macro- 

 spores 2 



2. Terrestrial ; plants with leaves in four or more ranks. 



Family 2. SELAGINELLACEaE, p. 137. 

 Aquatic, with leaves in clusters. 



Family 3. Iscetace^E, p. 142. 



Family I. LYCOPODIACEyt Lindl. 



Moss-like, terrestrial plants with small, lanceolate or subu- 

 late, sometimes oblong or roundish, simple leaves, arranged in 

 two to many ranks on trailing or sometimes erect, usually 

 branching stems. Sporangia i — 3-celled, solitary in the axils 

 or the leaves, or on their upper surface. Spores of one kind, 

 minute. Prothallia (so far as known) mostly subterranean, 

 with or without chlorophyll, moncecious. Contains four gen- 

 era, the following within our limits : 

 Leaves well developed, in 4 — many ranks ; sporano^ia i -celled. 



I. Lycopodium. 

 Leaves minute, abortive ; sporangia 3-celled. . II, Psilotum. 



I, LYCOPODIUM L. Club-moss. 



Perennial, terrestrial plants, with evergreen, one-nerved 

 leaves arranged in 4 — 16 ranks. Sporangia coriaceous, flat- 

 tened, reniform, one-celled, opening transversely, situated in 

 the axils of ordinary leaves, or with fruit-bearing leaves modi- 

 fied into bracts which are arranged in spikes either sessile or 

 peduncled. Spores copious, minute, sulphur-colored, inflam- 

 mable. Named from Gr. AiJjfos, wolf, and vov'i, foot, without 

 obvious application. Contains nearly one hundred species. 



* Plajtts with mostly upright stems, with alternating zones of 

 leaves and sporophylls. 



t Leaves hollow at their bases and appressed. 



I. L. selago L. Prostrate portion of stem very short, 

 abundantly rooting, soon curving upward and dichotomously 

 branching to form compact tufts (2' — f high) of vertically 



