VASCULAR CRYPTOGAMS. 193 



the Salviniaceae and their allies the Marsiliaceae, stand out as a distinct group. The 

 Ophioglosseae and Marattiaceae are closely related. The Equisetaceae are a rather 

 isolated group, and the remainder of the Vascular Cryptogams may be included in 

 the group of Lycopodineae. Peculiar groups, known only in the fossil state, of which 

 the better known are the Calamites, Annularieae and Asterophyllites, may be classed 

 with the Equisetaceae, under the name Equisetineae ; other groups are the Spheno- 

 phylleae, Lepidodendreae and Sigillarieae, the first of which are only heterosporous 

 Lycopodiaceae, while the mode of formation of the sporangia, and consequently the 

 systematic position of the Sigillarieae, is not yet certainly known, but they are pro- 

 bably nearest to the Gymnosperms. 



As regards the mutual relations of these groups, the Ophioglosseae and Marat- 

 tiaceae, brought together by Sachs under the name of Stipulatae, are connected by 

 their vegetative structure with the Ferns, but are distinguished from them by the for- 

 mation of the sporangia, in which they agree with the Equisetaceae and Lycopodiaceae, 

 and thus furnish a transition to the rest of the Vascular Cryptogams. The Vascular 

 Cryptogams may be all brought under two divisions founded on the mode of formation 

 of the sporangia ; the first is that of the Leptosporangiatae and includes the forms 

 in which the sporangia proceed from one cell, and the unicellular archesporium is 

 cut off by a peculiar geometrical series of divisions ; the second is that of the Euspo- 

 rangiatae, in which the sporangium is formed from a group of cells, and the arche- 

 sporium in the simplest case is the terminal cell beneath the epidermis (hypodermal) 

 of an axile row of cells ; to this division belong the Ophioglosseae and Marattiaceae 

 (Stipulatae), the Equisetineae and the Lycopodineae 1 . 



The arrangement given below is essentially the same as that adopted by Sachs 

 in his fourth edition; for the connection between the several groups the reader is 

 referred to what has just been said on the subject of the sporangia. Accordingly the 

 Vascular Cryptogams are distributed in four classes ; the Filicineae in the more 

 extensive sense (including the eusporangiate Ferns, namely the Marattiaceae and 

 Ophioglosseae), the Equisetineae, the Sphenophylleae, which are only fossil, and the 

 Lycopodineae. 



I. FILICINEAE. 



The greater number have spores of one kind only, which produce monoecious 

 prothallia, having the power of independent vegetation ; only the Salviniaceae and 

 Marsiliaceae have female macrospores and male microspores, forming rudimentary 

 prothallia which always continue attached to the spores. The sporophyte is an 

 unbranched or sparingly branched stem, with a copious growth of large usually 

 branched leaves and usually numerous roots. The sporangia are formed in large 

 numbers on ordinary or on metamorphosed leaves, and are usually collected together in 

 small groups (son'); in the Ophioglosseae they are more or less sunk in the tissue of 

 the sporophyll, and in them and in the Marattiaceae originate in a group of epidermal 

 cells, not in a single one as in the other Filicineae. The archesporium is a single cell. 

 Accordingly there are two divisions of the Filicineae, the Leptosporangiate nd the 



1 Goebel, Beitr. zur Entwicklungsgesch. d. Sporangien (Bot. Zeit. 1880, 1881), explains the 

 homologies with regard to the formation of the sporangia between the different groups of the Vas- 

 cular Cryptogams, and of these with the Phanerogams. 



M 



