392 



VA SCULAR CR YP TO GA MS. 



The second generation is a simple or repeatedly branched stem, usually possessing roots 

 and always bearing simple, unsegmented, comparatively small, but very numerous leaves, 

 which are traversed by only a single fibro-vascular bundle. All the branchings of the 

 stem and of the roots present the appearance of having originated dichotomously. 

 The sporangia are borne singly upon the upper surface of the base of the leaves, or 

 in their axils, or even in an extra-axillary position upon the stem. They originate as 

 masses of cells derived in part (Isoetes) from internal tissues, covered by the epidermis 

 which forms their walls. The archesporium is multicellular in some cases, unicellular 

 in others. 



Order I. Lycopodiaceas. The prothallia, which are developed from spores of one 

 kind only, are capable of independent growth and are monoecious. The roots branch 

 dichotomously in alternate intersecting planes, and neither stem nor root possesses 

 a single apical cell. The leaves have no ligula. The fibro-vascular cylinder of the 

 stem consists of numerous xylem-bundles, each of which is surrounded by phloem. 

 Families. (i) Lycopodieae. 



(2) Psiloteae. 



(3) Phylloglosseae. 



Order II. LigulatSB. The spores are of two kinds. Each macrospore forms a 

 rather large internal female prothallium, the archegonia of which only become exposed 

 when the wall of the spore is ruptured. Within each microspore a rudimentary pro- 

 thallium completely filling it is formed, certain cells of which give rise to the mother- 

 cells of the antherozoids. The second generation is of very different habit in the two 

 families. The leaves are always provided with a ligula borne above their base, and 

 below this lies the sporangium which contains either numerous microspores or four or 

 more macrospores. 



Families. (i) Selaginelleae. 

 (2) Isoeteae. 



CLASS VII. 



EQUISETINE^ 



The Sexual Generation (Oophore). The spores of the Equisetaceae, so soon as 

 they have attained the ripe condition (they retain their power of germination only 



^ G. W. Bischoff, Die kryptogamischen Gewachse (Niirnberg 1828). — W. Hofmeister, Vergl. 

 Unters. (1851). — Ditto, Ueber die Keimung der Equiseten (Abh. der konigl. Sachs. Gesell. d. Wiss. 

 1855, vol. IV. p. 168). — Ditto, Ueber Sporenentwickelung der Equiseten (Jahrb. fiir wiss. Bot. vol. III. 

 p. 283). — [Germination, Development, and Fructification of the Higher Cryptogamia (Ray Society), 

 pp. 267-306]. — Thuret (in Ann. des Sci. Nat. 1851, vol. XVI. p. 31). — Sanio, Ueber Epidermis 

 und Spaltoffnungen des Equis. (Linnaea, vol. XXIX. Heft 4).— C. Cramer, Langenwachsthum und 

 Gewebebildung bei E. arveme und sylvadcum (Pflanzenphys Unters. von Nageli und Cramer, 1855, 

 vol. III). — Duval-Jouve, Hist. Nat. des Equisetum (Paris 1864). — H. Schacht, Die Spermatozoidtn 

 im Pflanzenreich (Braunschweig 1864). — Max Reess, Entwickelungsgeschichte der Stammspitze von 

 Equisetum (Jahrb. fiir wiss. Bot. 1867, vol. VI. p. 209). — Milde, Monographia-Equisetoium, in Nova 

 Acta Acad. Leop. Carolinoe, 1867, vol. XXXV. — Nageli und Leitgeb, Entstehung und Wachslhum 



