402 ACROGENOUS PLANTS 



ft Leaves of two sorts, appearing ^-ranked. 



2* S. SipllS, Spring. Stem nearly prostrate, flaccid, much branched : 



leaves obliquely ovate, pellucid, spreading, with 2 rows of smaller 



appressed ones. 



Lycopodium apodum. L. $ Fl. Cestr. ed. 2. p. 589. 



FOOTLESS SELAGINELLA. 



Plant pale green, smooth, resembling a Moss. Stem 1 or 2 inches long, filiform. 

 Leaves less than a line in length, distichous, with smaller acuminate ones, mostly 

 appressed, on the upper side of the branches, nearly opposite the lateral ones. 

 Spikes % an inch to an inch in length, terminal and sessile, apparently a mere 

 continuation of the branches. 

 Sab. Moist, rocky, shaded spots : frequent. Fr. July, Aug. 



ORDER CXXII. HYDROPTERIDES. 



Cryptogamous aquatics, of diverse habit; the fructification borne either at the 

 bases of the leaves, or on submerged branches, consisting of two sorts of organs, 

 contained in indehiscent or irregularly bursting involucres, called sporocarps. 



SUBORDER I. ISOETIN'EAE. 



Apparently stemless perennials, growing in and mostly under water ; sporocarps 

 in the axils, and immersed in the inflated base, of the somewhat grass-like or 

 rather chive-looking leaves (clustered subulate-linear fronds). 



. ISO V ETES, L. 



[Gr. Isos, equal, and -Bios, year ; having the same appearance all the year.] 

 Stem a mere disk-like succulent rhizoma, rooting from beneath, and 

 covered above with the dilated imbricated bases of the elongated 

 sub-terete cellular fronds. Sporocarps ovoid, and plano-convex, 

 rather large, sessile in the axils of the fronds, adherent to their 

 excavated dilated bases and covered by an interior thin membran- 

 ' aceous scale, indehiscent, traversed internally by filaments forming 

 a kind of partitions ; those of the central fronds filled with minute 

 powdery spores, the exterior ones filled with larger roundish-quad- 

 rangular spores. 



1. I. lacustris? L. Rhizoma broad and depressed; fronds 

 mostly submersed, dark green ; spores roughish-granulated, scarce- 

 ly reticulated. 

 LAKE ISOETES. Quill-wort. 



Fronds numerous, 4 to 12 or 15 inches long, whitish at base, and imbricated in 

 a dense tuft, semi-terete and angular above the base, composed of longitudinal 

 tubes which are jointed, or interrupted by transverse partitions. 

 Hob. Shallow ponds, and shaded wet places : not very common. 



Obs. There is some doubt whether our plant may not prove to 

 be the /. Engelmdnni, Braun; but I have not had an opportunity to 

 determine the matter, satisfactorily. In the last edition of his 

 valuable Text Book, Prof. A. GKAY intimates that this Suborder should 

 rather be appended to the preceding Family of LYCOPODIACEAE ; 

 in which case, perhaps, the Selaginellas, or some of them, might be 

 arranged in the same Suborder with Isoetes. 



