4IO VASCULAR CRVPTOGAMS. 



education a field for work is here open. We must content ourselves now with briefly 

 stating all that is actually known, and with merely mentioning the less known forms 

 when occasion demands. 



Order I. Stipulat^e. 



Under this name, which is based upon the peculiar formation of stipules common 

 to the members of the two groups, I include the Ophioglosseae and the Marat- 

 tiaceae, for the relationship existing between them is manifested in several important 

 particulars. In both groups the prothallia are moncecious and capable of inde- 

 pendent growth ; but there is a tendency to dioecism in the Marattiaceae. That the 

 prothallia of the Ophioglosseae are subterranean, whereas those of the Marattiaceae 

 are not so, is a difference of physiological and not of morphological importance. The 

 stem of the second generation in both families is characterised by its very slight 

 growth in length, the usual absence of internodes and of any branching, the whole of 

 its surface being occupied by the insertions of the leaves, and by the development of 

 roots acropetally immediately behind its apex. The absence or rudimentary deve- 

 lopment of bundle-sheaths and of brown schlerenchyma in the ground-tissue of the 

 stem and of the leaves distinguishes these plants from the true Ferns. The Ophio- 

 glosseae diverge most widely from the Ferns in that their sporangia are imbedded in 

 the tissue of the leaf. The Marattiaceae present an intermediate condition in that 

 their sporangia are quite external to the leaf and are attached by a narrow base. 



Although it is not improbable, it is still an open question whether or not the 

 Osmundaceae are nearly related to these two families. Their petioles bear at their 

 bases lateral membranous wing-like appendages which may fairly be termed stipules, 

 but which are certainly very different from those of the Marattiaceae and Ophio- 

 glosseae. Further, the stem of the Osmundaceae, which is thickly covered with roots, 

 is not erect like that of the other two groups, and it is uncertain whether the 

 numerous lateral branches arise from it or from the petioles of the leaves. The 

 fructification seems to indicate a relationship, for it recalls the paniculate fructifi- 

 cation of the Botrychiae, but the fertile segments of the leaves have no mesophyll. 

 In this respect the Schizaeaceae resemble the Osmundaceae, but in other features, 

 more especially in the want of stipules, they differ from the Stipulatae. 



Although the connection of the Ophioglosseae with the Marattiaceae is tolerably 

 evident, it may be advisable to give a separate account of each family. 



Family I. OphioglossesB^ The Sexual Generation (Oophore). The pro- 

 thallium is at present known only in Ophioglossum pedunculosum and Botrychiu7n 

 Lunaria, In both cases it is developed underground. It is destitute of chloro- 

 phyll, and foniis a parenchymatous mass of tissue which, according to Mettenius, 

 has at first, in the species first-named, the form of a small round tuber, out 



* Mettenius, Filices horti botanici Lipsiensis. Leipzig 1856, p. 119. — Hofmeister, Abhandlungen 

 der konigl. Sachs. Gesellsch. der Wissens. 1857, p. 657. — [On the Germination, Development and 

 Fructification of the Higher Cryptogams, Ray Soc. 1862, pp. 307-317.] — Russow, Vergleich. Unters. 

 St. Petersburg, 1872, pp. 117 ff. - [HoUe, Ueb. Bau und EntwickeUing der Vegetationsorgane der 

 Ophioglossen, Bot. Zeitg. 1875.] 



