Note 10 — Chapter III · THE MORPHOLOGICAL COMPOSITION OF PLANTS, CONTINUED.

I am indebted to Dr. Hooker for pointing out further facts supporting this view. In his Flora Antarctica, he describes the genus Lessonia (see Fig. 37), and especially L. ovata, as having a mode of growth simulating that of the dicotyledonous trees, not only in general form but in internal structure. The tall vertical stem thickens as it grows, by the periodical addition of layers to its periphery. That even Thallophytes should thus, under certain conditions, present a transversely-increasing axis, shows that there is nothing absolutely characteristic of Phanerogams in their habit of stem-thickening. Mr. Tansley gives me further verification by the statement that “it is also now certain that members of the Equisetineæ and Lycopodineæ, as well as some Ferns which flourished in Carboniferous times, had secondary thickening in their stems quite comparable to that of modern Dicotyledonous trees.”