LYCOPODIACEAE 27 



elongated and enlarged upward, with a black girdle at the base of the mostly decidu- 

 ous, white-margined teeth and rarely also at their bases; ridges of the sheath with a 

 faint central carina and sometimes with faint short lateral ones: stomata arranged 

 in single series; central cavity very large, the wall of the stem very thin. 



Along streams, especially in clay soil, New Jersey to British Columbia, south to North 

 Carolina, Louisiana and California. 



Order 5. LYCOPODIALES. 



Terrestrial or epiphytic plants with spores produced in sporanges borne in 

 the axils of scale-like leaves. 



Spores all of one sort and size. 



Sporanges 1-celled, transversely 2-valved: stems leafy. Fam. 1. LYCOPODIACEAE. 



Sporanges 2-3-celled, opening by 2-3 apical valves: stems and 



branches nearly naked. Fam. 2. PSILOTACEAE. 



Spores of two kinds and sizes, megaspores and microspores. Fam. 3. SELAGINELLACEAE. 



FAMILY 1. LYCOPODIACEAE Michx. CLUB-MOSS FAMILY. 



Moss-like plants, with erect, trailing or creeping stems. Leaves often nu- 

 merous, in 2-several series: blades narrow. Sporanges 1-celled, solitary in the 

 axils of leaf -like or scale-liks bracts (sporophyls), sometimes forming compact 

 cones (strobiles). Spores uniform, minute. Prothallia (as far as known) mon- 

 oecious, mostly subterranean. 



1. LYCOPODIUM L. 



Perennial evergreen plants various in habit. Leaves in 4-16 series: blades 

 1-nerved. Sporanges 1-celled, in the axils of more or less distant leaf-like bracts or 

 collected into terminal compact bracted cones, transversely 2-valved. Spores of one 

 kind, sulphur-yellow, copious, readily inflammable. CLUB-MOSSES. 



Sporophyls not closely associated in terminal spikes. 



Stems rigidly erect; leaves ascending, nearly uniform. 1. L. Selago. 



Stems ascending: leaves spreading or deflexed, longer or shorter in alternating 

 zones. 



Leaves broadest above the middle, there usually erose-denticulate. 2. L. lucidulum. 



Leaves linear or nearly so, entire or minutely denticulate. 3. L. porophilum. 



Sporophyls closely associated in terminal spikes. 



Sporanges subglobose: sporophyls similar to the foliar leaves. 



Sporophyls less than 6 mm. long, incurved, often only slightly 



toothed at the base. 4. L. adpressum. 



Sporophyls more than 8 mm. long, not incurved, usually much 



toothed. 

 Stems mostly recurved or arching; leaves in many ranks, spreading 



radially. 5. L. alopecuroides. 



Stems prostrate: leaves twisted, lying in one plane. 6. L. prostration. 



Sporanges compressed, reniform: sporophyls bract-like, very unlike 



the foliar leaves. 

 Stems without leafy aerial branches, the elongate peduncles arising 



directly from the prostrate stem. 7. L. Carolinianum. 



Stems with numerous erect or assurgent leafy branches, the spikes 



terminal upon some of these. 

 Leaves of the ultimate branches in 6 or more rows, spreading: 



spikes sessile. 



Spikes few, stout, erect. 8. L. obscurum. 



Spikes numerous, short, nodding. 9. L. cernuum. 



Leaves of the ultimate branches in 4 rows, appressed, mostly 



decurrent: spikes pedunculate. 

 Ultimate branches conspicuously flattened: leaves of the 



under row greatly reduced, minute, triangular-cuspidate. 10. L. complanatum. 

 Ultimate branches narrower and less flattened: leaves of the 



under row scarcely smaller, acicular. 11. L. tristachyum. 



1. Lycoppdium Selago L. Stems rigidly erect from a short slender curved base, 

 several times dichotomous, the vertical branches forming compact even tufts 5-15 cm. 

 high. Leaves uniform, crowded, appressed or ascending, narrowly deltoid-lanceolate 

 or somewhat acicular from a broader base, shining, pale green or yellowish, 4-8 mm. 

 long, usually entire, acute, those bearing the sporangia (below the summit) a little 

 shorter: plant often gemmiparous above. 



On rocks and shaded cliffs, Labrador, Greenland and Alaska, south to Maine, Michigan 

 and Washington and in the mountains to North Carolina. Also in Europe and Asia. 



2. Lycopodium lucidulum Michx. Stems rising 1.5-2.5 dm. from a decum- 

 bent base, 1-3 times dichotomous, the few leafy vertical branches loosely clustered. 

 Leaves dark green, shining, wide-spreading or finally deflexed, acute, somewhat 



