307 



Tribe. 1. FILICOIDE^ or FERN-LIKE PLANTS. 



Endogen*: Cryptogam*, Dec. Thcor. Elem. 249. (1829).— Pseudocotyledoneje, Classes 2, 

 3, and 4 ; Agardh Aph. 103. (1822).— Heteronemea, Fries Syst. Crb. Vcg. 33. (1825), ire 

 part.- Acotyledones, Class 3 ; Ad. Brongn. in Diet. Class. 5. 159. (1824).— Crypto- 

 gamic*, 3d Circle. T. F. L. Nees v. Esenbeck and Ebermaier Handb. der Med. Bot. 1. 

 18. (1830.) 



Diagnosis. Flowerless plants, with a stem having a vascular system and 

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

 tinct axillary or dorsal thecae. 



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

 cese, 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 Marsilea- 

 cese 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 Equisetacese. 265 Lycopodiacero. 



264 Filices. 266 Marsileacse. 



CCLXIII. EQUISETACE^E. The Horse-tail Tribe. 



Equisetaceje, Dec. Fl. Fr. 2. 580. (1815) ; Agardh Aph. 119. (1822) ; Kaulfuss Enum. FHi- 

 cum, 1. (1824); Greville Flora Edin. xiii. (1824): Adolphe Brongniart Hist. Veg.Fosf, 

 99. (1828.) 



Diagnosis, Flowerless plants, with their sporules surrounded by elastic 

 clavate filaments, and enclosed in thecae arising from the scales of terminal 

 cones. Vernation straight. 



Anomalies. 



Essential Character. — Leafless branched plants, with a striated fistular stem, beneath 

 the cuticle of which silex is secreted ; the articulations separable, and surrounded by a mem- 

 branous toothed sheath. Reproductive organs consisting- of 1-valved theca bursting- longitu- 

 dinally, and arranged upon cuneate scales, which are collected into strobiliform heads; spo- 

 rules surrounded by minute granules, and having- at their base 4 elastic clavate filaments, 

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



Affinities. The very remarkable plants known by the vulgar name of 

 horsetails, seem to have no very decided affinity to any existing tribes. With 

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

 want of stamens and pistils, 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, ap- 

 proaching Coniferae through Cycadess more closely than any thing else. The 

 curious structure of their stem is well described by Ad, Brongniart in his His- 



