SELAGINELLACE.E, 639 



* * Biacteal leaves wider than those of the stem. 

 -f- Leaves of the stem equal and alike. 



5. L. Clavatum, L. Stem very long, terete, creeping, with numerous 

 short and erect leaf y branches ; peduncles with scattered leaves, each bearing 

 2-3 linear cylindrical spikes ; leaves in several rows, subulate, entire, incurved, 

 pointed, liiie the ovate erosely-denticulate bracts, with a spreading bristle. — 

 Mountains of North Carolina, and northward. — Peduncles 4' -6' long. 



6. L. cernuum, L. Stem forking near the base (6' -12' long), the di- 

 visions arcuate-recurved, and rooting at the tip, the short alternate branches 

 forking, and terminated by the short (4" -6") nodding spike; leaves about 

 6-rowed, linear-subulate, entire, spreading or recurved; those of the spike 

 ovate, acuminate, witli bristly margins. — Springy sandy places, Florida and 

 Alabama, near the coast. 



-1- -f- Leaves of the flattened stem and branches unequal. 



7. L. dendroideum, Michx. Stem erect (6'- 12'), clothed with scat- 

 tered appressed subulate and entire leaves, simple below, bearing above nu- 

 merous forking and spreading fan-like mostly compressed branches ; lower 

 row of leaves, and sometimes the upper, shorter, the lateral ones spreading; 

 peduncles short, bearing one or more cylindrical spikes ; bracts spi'eading, 

 ovate, acute, crenate on the margins. (L. obscurum, L.) — High mountains 

 of North Carolina, and northward. 



8. L. Carolinianum, L. Stem creeping, pinnately branched, naked 

 and rooting beneath ; upper leaves short appressed, the lateral ones widely 

 spreading, lanceolate, acute, entire; peduncle slender (6'- 12' high), clothed 

 with scattered subulate leaves, and bearing a single linear spike ; bracts ovate, 

 acuminate, spreading. — Low pine barrens. — Stem 2' -8' long. 



9. L. COraplanatum, L. Stem long and creeping, the numerous erect 

 branches successively forking into many linear crowded flattened branclilets; 

 leaves minute, subulate, imbricated in 4 rows, the lateral ones slightly spread- 

 ing ; peduncles with minute scattered leaves, slender, bearing 2-4 erect cylin- 

 drical spikes — Woods along the Alleghanies, and northward. — Stem 2°- 10° 

 long. 



2. PSILOTUM, R. Br. 



Sporangia of one kind sessile, globulai", opening at the apex into 2 - .3 valves, 

 and filled with very minute powdery spores. 



1. P. triquetrum, Swartz. Stem forking, compressed, the baanches 

 3-angled ; leaves very minute, bristle-like; sporangia spiked, 3-celled, the cells 

 imperfectly 2-valved. — Florida. 



Order 167. SELAGINELLACE^. 



Low moss-like terrestrial plants, with branching stems, and scale- 

 like leaves. Sporangia of two kinds, either in the same or in separate 

 axils, one kind as in the preceding ordei-, the other containing few 

 (mostly 3-4) larger spores. 



