LTCOPOCIACEJE. (CLUB-MOSS FAMILY.) 675 



* Leaves all alike and uniformly imbricated ; those of the spike similar. 



1. S. selaginoides, Link. Sterile stems prostrate or creeping, small and 

 slender; the fertile thicker, ascending, simple (I' -3' high) ; leaves lanceolate, acute, 

 spreading, sparsely spinulose-ciliate. (S. spinosa, Beauv. S. spinulbsa, Braun.) 



— Wet places, New Hampshire (Pursh), Michigan, Lake Superior, and north- 

 ward: rare. — Leaves larger on the fertile stems, yellowish-green. (Eu.) 



2. S. rupestris, Spring. Much branched in close tufs (1'- 3' high); leaves 

 densely appressed-imbricated, linear-lanceolate, convex and with a grooved keel, 

 minutely ciliate, bristle-tipped ; those of the strongly quad-angular spike rather 

 broader; the two sorts of fructification in the same axils. (Lycopodium rupes- 

 tre, L.) — Dry and exposed rocks: very common. — Grayish-green in aspect, 

 resembling a rigid Moss. 



* * Leaves shorter above and below, resembling stipules : the lateral larger, 2-ranked. 



3. S. apus, Spring. Stems tufted and prostrate, creeping, much branched, 

 flaccid ; leaves pellucid-membranaceous ; the larger spreading horizontally, ovate, 

 oblique, mostly obtuse ; the smaller appressed, taper-pointed ; those of the short 

 spikes nearly similar ; larger spore-cases copious at the lower part of the spike. 

 (Lycopodium apodum, L.) — Low, shady places : not rare, especially southward. 

 — A delicate little plant, resembling a Moss or Jungermannia. 



3. ISOETES, L. Qcillwort. (PI. 20.) 



Stem or trunk a fleshy more or less depressed corm, rooting just above its 2- 

 lobed (or in many foreign species 3-lobed) base, above covered with the dilated 

 and imbricated bases of the awl-shaped or linear somewhat quadrangular leaves, 

 which include 4 air-tubes, intercepted by cross partitions. Sporangia, or sporo- 

 carps, pretty large, orbicular or ovoid, plano-convex, very thin, sessile in the 

 axils of the leaves, and united at the back with their excavated bases (the thin 

 edges of the excavation folding round partly cover them, forming the velum), 

 traversed internally by transverse threads ; those of the outer leaves filled with 

 large spherical spores (macrospores) , their whitish crustaceous integument marked 

 by one circular, and on the upper surface by 3 radiating elevated lines (circum- 

 scribing a lower hemisphere, and three upper segments which open valve-like in 

 germination) : those of the inner leaves filled with very minute and powdery 

 grayish spores (microspores) ; these are always obliquely oblong and triangular. 



— Mostly small aquatics, grass-like or rush-like in aspect, some always sub- 

 merged, others amphibious, a few living in merely moist soil, maturing their 

 fruit in late summer and early autumn, except No. 7, and some forms of No. 6. 



Genus much investigated of late by Prof Durieu and the late J. Gay of 

 France, and by Prof Braun of Berlin, newly elaborated for this edition by Dr. 

 George Engelmann. 



* Growing under water, only accidentally or in very dry seasons out of water : leaves 



without stomata (except in some forms of No. 3), and without peripherical bast- 

 bundles. 

 1. I. lactistris, L. Leaves (10-25 in number, 2' -6' long) dark green, 

 rigid ; sporocarps ovoid or circular, the upper third or less covered by the 

 velum, free part pale and unspotted ; both kind of spores the largest of our spe- 



