314 



Geography. It is the opinion of M. Ad. Brongniart, that in the earlier 

 ages of the world these plants attained a gigantic size, equalled only by the 

 timber-trees of our forests ; and it is certain that remains of what appear to 

 have been species of this tribe are abundant in the coal measures, along with 

 Ferns. At the present day they do not exceed the height of 2 or 3 feet in any 

 instance, and are visually weak, prostrate plants, having the habit of Mosses. 

 In geographical distribution they follow the same laws as Ferns, being most 

 abundant in hot humid situations in the tropics, and especially in small islands. 

 As they approach the north. they become scarcer ; but even in the climate of" 

 northern Europe, in Lapland itself, whole tracts are covered with Lycopodium 

 alpinum and Selaginoides. 



Properties. Lycopodium clavatum and Selago excite vomiting ; the 

 powder contained in the thecal is highly inflammable, and is employed in the 

 manufacture of fireworks. According to M. Vastring, they are likely to be- 

 come of importance in dyeing. He asserts, that woollen cloths boiled with 

 Lycopodiums, especially with L, clavatum, acquire the property of becoming 

 blue when passed through a bath of Brazil wood. Lycopodium Phlegmaria is 

 reputed an aphrodisiac. 



Examples. Isoetes, Lycopodium, Psilotum, Tmesipteris. 



CCLXVI. MARSILEACEiE. The Pepperwort Tribe. 



RmzocARpiE, Batsch. Tab. Aff. (1802); Agardh Apk. 111. (1822).— Rhizosperms, Roth. .'/ 



Fl. Fr. 3. 577. (1815).— Hydropterjdes, Willd. Sp. Pl.b. 534. (1810).— Maesileacejs. 

 R. Brown Prodr. 166 (1810); Grcv. Fl. Edinens. xii. (1824); Ad. Brongn. in Diet 

 Class. 10. 196.(1826); Dec. and Duby, 542. (1828).— Salvinieje, Juss. in Mir b. Elc- 

 mens, 853. (1815.) 



Diagnosis. Flowerless plants, with their sporules enclosed in thecae, con- 

 tained within close involucra. 

 Anomalies. 



Essential Character.— Creeping- or floating plants. Leaves either petiolate and divided 

 (or petioles destitute of lamina), rolled up in vernation, or imbricated and sessile. Reproduc- 

 tive organs enclosed in leathery or membranous involucra, and of two kinds, the one consist- 

 ing' of membranous sacs, containing a body or bodies, which germinate, the other of similar 

 sacs, containing' loose granules. 



Affinities. It is probable that this tribe, as now constituted, comprehends 

 two exceedingly different forms of organization, of which one is represented by 

 Marsilea and Pilularia, and the other by Azolla and Salvinia. I follow M. 

 Adolphe Brongniart in this division, adopting from him many of the succeeding 

 observations. 



The tribe to which Pilularia and Marsilea belong consists of creeping plants, 

 having the circulate vernation of Ferns, with their reproductive organs in inde- 

 hisccnt leathery cases, called involucra, springing either from the root, or from 

 the petioles of the leaves. These involucra arc separated internally by mem- 

 branous partitions, and contain oval bodies of two kinds, one of which has been 

 called anthers, and the other capsules. 



Beautiful figures of Marsilea vestita and polycarpa have been published by 

 Messrs. Hooker and Greville, at t. 159 and 160 of their noble Icones Filicum, 

 From these it is clear that the involucrum of the genus consists of an involute 

 frond, of the same degree of analogy to the true frond as a carpellary leaf to a 

 true leaf. It further appears that the reproductive bodies arise from the veins 

 of this involute frond, and are therefore analogous, as to position, to the sori of 



