470 MARSILEACEiE. 



the summits of the branches a whitish appearance. Spikes 3 — 6 lines lon^, 

 square and scarcely distinguishable from stem below. Spore-cases mostly wiUi 

 larger grains. Snail Rock Club-moss. 



2. S. apus Spring : cespitose ; stems flaccid, creeping, flat ; leaves in 4 

 rows, not auricled ; those of the lateral rows roundish-ovate, oblique and 

 spreading ; the intermediate ones on the upper side of the branches smaller, 

 appressed ; spikes dense, leafy. ( Torr. N. Y. FL) Lycopodium apodum 

 Linn. L. albidulum Pursh. 



Wet rocky places. N. Y. to Flor. July, Aug. (I)?— A small pale green 

 moss-like plant. Stem.^ numerous, 1 — i inches long, with somewhat flattened 

 branches. Leaves small, membranaceous. Spikes terminal, 2 — 4 lines long, 

 with the larger spore-cases at the lower part. Resembles S. Helvetica of Europe. 



Moss-like Selagiiyella. 



Order CLI. MARSILEACE^.— Pepperworts. 



Fructification enclosed in indusia or involucres of two kinds ; 

 the one clustered and stalked, or crowded confusedly without 

 stalks, and distinct from the second, or mixed with it, or in con- 

 tact with it ; the other, simple oval bodies, sometimes having a 

 terminal nipple, from which germination uniformly proceeds. — 

 Stemless plants, creeping or floating. Leaves usually petioled, 

 sometimes sessile and scaly, occasionally destitute of lamina and 

 rolled up in vernation 



1, AZOLLA. Lam. — Azolla. 



(Said to be derived from the Greek a^w, to dry, and aWvfxi, to destroy ; it being 

 quickly killed by dryness.) 



Reproductive organs in pairs, attached to the stem and 

 branches, one above the other, concealed in a membranaceous 

 indusium. Capsules? of each pair either difform — in which 

 case the lowest one is oblong-ovoid, the upper globose — or both 

 of either kind ; the upper half generally tinged with red. The 

 oblong-ovoid capsule opens by circumcision ; the globose one has 

 a rugose surface from the pressure of the secondary capsules. 

 (Griffithjin Lind. Veg. King.) 



A. Caroliniana Wilid: leaves 2-ranked, imbricate, ovate-oblong, obtuse, 

 spreading, reddish beneath. 



Lakes and slow flowing streams. N. Y. to Flor. W. to Miss. ; rare in the 

 N. S. (J). — A small plant floating on water, and somewhat resembling a Jun- 

 germannia, dark green, pinnately branched. Leaves less than half a line 

 long. Sterile indusia solitary or in pairs at the base of the much larger ste- 

 rile ones. Carolinian AzoUa. 



