THE TASMANIAN FLORA. 279 



sometimes specially modified, or the sporangia sunk in the substance 

 of the leaf. Spores all similar; 

 IIydropterid<s (Wsder Ferns). Sporangia in greatly altered capsule- 

 shaped leaves. Spores of 2 kinds. 



ISOETACEyE. 



Spores of two kinds, contained in separate but similar oblong sporangia. 

 Sporangia half-buried in the upper surface of the expanded leaf base, solitary. 

 Water plants with a persistent, enlarging, bulbate stem, from which arise 

 crowded erect leaves with expanded flat bases and cylindrical quilHike 

 laminae. ,.j - 



An anomalous order of no very close afl&nity to any living plants. Apparently 

 related on the one hand to Eusporangiate ferns {Ophioglossum, &c.), on the other 

 to Heterosporous lycopods (SelaffineUa). 



ISOETES. 

 The character of the order. 



I. LACUSTRis, Linn. Leaves f-8 inches, rigid, but the longer ones flaccid when 

 dry. /. gunnii and I. stuartii, Braun., I. humilior and elatior, F. v. M., 

 included. 



World-wide distribution. 



The plant varies considerably in light and shade and other local 

 characters, and I have thought it better, pending further acquaintance, 

 to follow Bentham, and retain all forms as one species. 



LYCOPODIA CEjE. 



Spores all of one sort, minute, in sporangia formed on the upper surface or 

 axils of the leaves, solitary, and relatively large. Fertile leaves sometimes 

 •difPering from barren ones, and crowded together. 



Plant very small. Leaves linear, nearly, as long as 



the stem, all basal 1. Phylloglossum. 



Leaves dispersed. Sporangia small, axillary ... 2. JOycopodium. 



Leaves dispersed. Sporangia large, constricted in 



the middle S. Tmesipteris. 



1. PHYLLOGLOSSUM. 

 Fertile leaves minute and crowded, in a small cone on an erect slender stem, 

 I inch. Leaves linear, erect, all basal, and about as long as the stem. . 

 P. drummondi, Kunze. The only species in the genus. 

 G-eorge Town. West Australia, Victoria, New South Wales. 



2. LYCOPODIUM. 



Fertile leaves crowded together, sometimes in a denser mass than in the case 

 of foliage leaves. Leaves dispersed along the branches. 



i. Leaves of two sizes ..,. ... L L. scariomm. 



Leaves minute. Plant erect ... 2. L. densum. 



Plant procumbent or flaccid ... n- 



ii. Fertile leaves in a dense long-stalked spike ... 3. L. clavatum. 



Spike sessile, usually lateral. Leaves acute ... 4<. L. laterale. 

 Fruiting portion hardly difierentiated. Leaves 



blunt 5. L.selago. 



