310 



Tribe I. FILICOIDE^, on FERN-LIKE PLANTS. 



ExDOGENyE Cryptogam.e, Dec. Thior. Eltm. 249. (1829) — Pseudocotyledokea:, 



Classes 2, 3, and 4; Agardh Jph. 103.(1822) HeterOnemea, Fries Stjst. 



Orb. Veg. 33. (1825), in part Acotyledoxes, Class 3; Ad. Brongn. in Did. 



Class. 5. 159. (1824). — Cryptogamic.e, 3d Circle, T. F. L. Nees v. Esenbeck 

 and Ebermaier Handb. 'der Med. Bot. 1.18. (1830.) 



Diagnosis. Flovverless plants, with a stem having a vascular system 

 and distinct leaves ; their sporules having a proper integument, and contained 

 in distinct axillary or dorsal thecse. 



This differs from the third class of M. Brongniart in the exclusion -of 

 Characeee, which are known to be destitute of a vascular system, and which 

 more properly belong to the next section, connecting it with the third; as 

 Marsileaceae unite the first and second. Von Esenbeck and Ebermaier also 

 exclude this family, referring it to the third or leafless tribe. 



LIST OF THE ORDERS. 



263 Equisetaceae. ' I 2G5 Lycopodiaceae. 



264 Filices. 266 Marsileacea.. 



CCLXIIL EQUISETACE^. The Horse-tail Tribe. 



EauiSETACE^, Dec. Fl. Fr. 2. 580. (1815) ; Agardh Aph. 119. (1822) ; Kaulfuss Enum. 

 Filicum, 1.(1824); Greville Flora Edin. xiii. (1824); Adolphe Brongniart Hist. 

 Veg. Foss. 99. (1828.) 



Diagnosis. Flowerless plants, with their sporules surrounded by elastic 

 clavate filaments, and enclosed in thecae arising from the scalesof terminal 

 cones. Vernation straighl,. 



Anomalies. 



EssEXTiAi. Character Leafless branched plants, with a striated fistular stem, 



beneath the cuticle of which silex is secreted ; the articulations separable, and surrounded 

 by a membranous toothed sheath. Reproductive organs consistinjj of 1-valved theca; Imrst- 

 ing longitudinally, and arranged upon cuneate scales, which are collected into strobiliform 

 heads ; spornlcs surrounded by minute granules, and having at their base 4 -elastic clavate 

 filaments, twisted spirally round them when dry, but expanding when moistened. 



Affinitiks. The very remarkable plants known by the vulgar name 

 of horsetails, seem to have no very decided afiinity to any existing tribes. 

 With Ferns their relation is far from obvious, depending almost entirely upon 

 the want "of sexes, and the presence of annular ducts without spiral vessels. 

 In the arrangement and appearance of their reproductive organs they have a 

 striking resemblance to Zamia, and in general aspect to Casuarina. Their 

 germination is that of Cellular plants, and approaches nearly to Mosses. 

 Upon the whole, they must be considered an exceedingly anomalous tribe," 

 approaching Coniferas through Cycadea; more closely than any thing else. 

 The curious structure of their stem is well described by Ad. Brongniart in 

 his History of Fossil Vegetables, as are, indeed, all the parts of their organi- 

 sation : see Tables 11 and 12 of that work. This ingenious writer entertains 

 the dpinion that the green body, which is known to be the sporule, is a naked 



