170 CHAEACTEES OF TRIBES AND GENEEA. 



Tribe 9. CEEATOPTERIDB^ (Plate 9). 



This tribe consists of one species only, originally named 

 by Linnaeus AcrosticTium thalictroides, and by later botanists 

 it has been characterised under no less than nine different 

 generic and a dozen specific names. 



79. CEEATOPTEEIS, Brongn. (1821). 

 Ellobocarpus, Kaulf. ; Parkeria, Hook. 



Vernation fasciculate, erect, acaulose (plant annual). 

 Fronds fragile ; the fertile decompound ; segments forked, 

 linear ; margins revolute, membranaceous, conniving, 

 induseeform. Veins transversely elongated, distantly anas- 

 tomosing. Sporangia occupying the transverse venules, 

 superficial, large, disposed in a simple series, constituting 

 two linear sub-parallel sori. 



Type. Ceratopteris thalictroides, Brongn. 



Illust. Hook, and Bauer, 1. 12 ; Moore Ind. Fil., p. 94 A. ; 

 J. Sm. Ferns Brit, and For., fig. 60 ; Hook. Syn. Fil., 

 t. 3, fig. 32. 



OBS. This genus is founded on a very remarkable and 

 peculiar Fern, being one of the few that are annual. It is 

 found widely spread in the tropics of both hemispheres, 

 growing in wet places or even in shallow water, the sterile 

 fronds floating on the surface, and being viviparous, and with 

 the ready germination of the numerous spores, and rapid 

 growth of the fronds, makes it abundant in the places of its 

 growth. Besides the special habit of the plant, the sporangia 

 exhibit a peculiar structure, being large globose, and either 

 furnished with a broad nearly vertical or short imperfect 

 ring, which is described by some authors as horizontal, 

 and consequently has led Ceratopteris to be associated with 



