9 



ENDOGENS. 



Table I. 



I am aware that there is no evidence to show that any near affinity exists between Lemnacece and Ricciacea, further than that the habit of some species of Riccia is so much like that of 

 Lemna, that they are stated to have been mistaken for species of that genus by some authors, while species of the latter genus have in fact been described as belonging to the former ; and although 

 habit is often of little value as a character among phanerogamous plants, it is acknowledged to be of more importance among the cryptogamous. But as the present arrangement includes the placing 

 of all the cryptogamous families in relation with the phanerogamous, the Endogens should in all probability be compared to one at least of their lowest forms ; and as the Ricciacece have no affinity 

 with the apetalous forms of the Exogens, a negative evidence is afforded of their being the cryptogamous form of the Lemnacece. 



An affinity between Marchantiacece (which are scarcely distinct from Ricciacece) and Zosteracea is suggested by Dr. Lindley, who remarks that the pollen of Zosteracece is " in a condition 

 that may be well compared to the*elaters of Marchantia and its allies, and totally different from all that is known in other flowering plants." (Veg. Kingd. p. 145). But whether this should now be 

 regarded as more than an analogy may with some botanists perhaps be a question. A decided resemblance however between Lemnacece and Marchantiacece as regards mode of growth has been pointed 

 out by Hofmeister. In Lemna the young shoots proceed from the median line on the under surface of the frond, or at least they are connected with it by distinct bundles of tissue like ribs, which may 

 be seen on its under surface ; and in Marchantia " a process of cell-multiplication commences in individual cells (usually near the median line) of the under side of perfect shoots, by means of 

 which slender, delicate shoots are produced, which soon throw out rootlets, and which, by the decay of their posterior parts, separate from the mother plant and become independent individuals."* 



It also deserves notice that the translucent involucre of Marchantiacece occurs in Naidece and in Monochoria enclosing two flowers; — that in Riellaf the archegonium is enclosed in a 

 veil much like the membranous spathe of Lemna, so that supposing the seed of a Lemna when single to have several embryos (as sometimes occurs in the onion,) and that they were acotyledonous, 

 the approach would be very close, especially if the testa were adherent to the carpel; — and that in Marchantia and RebouUlia% the conical head of flowers, the upper half of which is barren, 

 is a miniature representative of the spadix of an Arum. And possibly some analogy may be traced between the Endogens and Lichenales in the physiological character of the Bromeliacea 

 growing freely without any] source of nutrition, except the surrounding atmosphere, and their habit also is not unlike that of Parmeliacece, e. g. Tillandsia usneoides, if it is admitted that leaves 

 may be compared to foliaceous branches. (V. Obs. On the Natural System, p. 2.) I however regard the Fungales and Lichenales as having no representatives among phanerogamous plants like 

 the higher Cryptogams and even the Algales remotely, and have therefore placed them separately at the commencement of the Sections of Cryptogams. 



The habit of Tacca is so much like that of Aristolochiacea as to have led to repeated comparisons (Lindl. Veg. Kingd. p. 149,) and it may also deserve notice that in one species of Maranta 

 the same peculiarity occurs as in Valeriana, viz. the fertile carpel and stamen are always lateral in relation to the flower but anterior in relation to the axis of the inflorescence§ ; and also that 



* Currey's Translation of Hofmeister on the Higher Cryptoganria, p. 108. 



t L. c. PI. XIV. f. 16. 



% L. c. PI. XV. f. 12; and PI. XVI. f. 17. 



§ For further explanation of this singular character, V. Ann. Nat Hist. 2nd Ser. Vol. XI. 



