Organography of plants, especially of the archegoniatae and spermaphyta . rs develop out oftheir edge, a developmentalways absent from the epi-geous .shoot. The summitof the shoot then swells upinto a tuber, Kjj, the vege-tative point remains coveredby the youngest leaf-prim-ordia, the epigeous parts dieoff with the advent of thedry period of the year, whilst the tuber persists. If it shoots out again itcan branch, and so give origin to a small tuft of plants. If a sporogoniumhas been developed the plant nevertheless continues itself usually by atuber-shoot (see Fig. 61). The formation of tube
Organography of plants, especially of the archegoniatae and spermaphyta . rs develop out oftheir edge, a developmentalways absent from the epi-geous .shoot. The summitof the shoot then swells upinto a tuber, Kjj, the vege-tative point remains coveredby the youngest leaf-prim-ordia, the epigeous parts dieoff with the advent of thedry period of the year, whilst the tuber persists. If it shoots out again itcan branch, and so give origin to a small tuft of plants. If a sporogoniumhas been developed the plant nevertheless continues itself usually by atuber-shoot (see Fig. 61). The formation of tubers in Geothallus tuberosus is very like that in the Fos-sombronia just described, but the stalk which ensures the burying of the tuber inthe ground, and which occurs in the species of Anthoceros as well as in Fossom-bronia tuberifera, is wanting. In Geothallus that portion of the tuber which containsthe reserve-material is bounded by one or two layers of cells with thick, dark walls,and this is characteristic. The tubers arise both upon fertile and upon sterile FjG. 62. Aiitlioceros dichotomus. Portion of the tliallusthe thickenet) middle part two long-stalked tubers arise. FromOn the left division of the right thallus-lobe the outline of a young tuber isvisible. The dark spots on the left indicate colonies of Nostoc,Magnified 17. I found it along with Anthoceros argentinus, a form which also produces tubers, in a gatheringfrom Pelegua in Chili. It is very nearly allied to a species T found at Tovar in Venezuela. FORMATION OF TUBERS 69 Anthoceros dichotomus and A, argentinus. The tubers of the twospecies of Anthoceros, A. dichotomus and A. argentinus, which have beenexamined, may be regarded as transformed branches of the thallus, whoseends have become swollen and filled with reserve-material. So far asmaterial has sufficed for examination of the structure of these tubers, itcorresponds with that of the tubers of Anthoceros tuberosus ^ The tubersare surrounded by some
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