Historic fossil cycads ; Accelerated cone growth in Pinus / by G.R. Wieland.

  • Wieland, G. R. (George Reber), 1865-1953.
Date:
1908
Catalogue details

Licence: In copyright

Credit: Historic fossil cycads ; Accelerated cone growth in Pinus / by G.R. Wieland. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    As we have seen, Cycadeoidea Reichenbachiana adds another member to the long series of trunks extending from columnar types which have mostly, though not always, large leaf bases, to the great branching types from America, which are mostly characterized by leaf bases of moderate or small size. Moreover, while C. Reichenbachiana is a columnar form, its flower bud agrees closely with that of the branching cycads of the Black Hills, especially C. dacotensis. It there- fore remains to add that in the light of these new facts con- cerning long known European cycads, the family name Cycadeoideae used by Robert Brown (1828) certainly includes all the forms which English writers on fossil plants have much later mistakenly placed in their so-called Bennettiteae. Simi- larly, the proposal that Cycadeoidea (1827) shall be the generic term used for stems without recognizable fructifications cannot be accepted for the simple reason that not only are the Buck- land specimens vegetatively like the other trunks from Europe as well as the American forms, but, to go no further than the evidence afforded by the original descriptions, the tangential section figured by Buckland eighty years ago clearly shows a large and characteristic peduncular bundle. As to the genus Bennettites (1867), this can at the very most include two or three species so far as known, the great majority of the species of Cycadeoideae falling within other genera. And so far as truly problematic trunks of unknown fructification and really doubtful vegetative characters are concerned, it only needs to be remarked that there is already at hand for their reception a plethora of such names as Yatesia, Withamia, BecJclesia, Fittonia, Olathraria, Cylindropodium, and Bolbopodium. It would certainly be as illogical to insist that we require to relegate to a minor position a correctly used generic name for the sake of a handy nomenclature for cycad trunks without distinct or distinctly conserved fructifications, as it would be to say that we can never learn the fructification of a fossil whose vegetative features are the first to be discovered, or are, as in this case, the first to be understood. Clearly, therefore, those who would further use the family name Bennittiteae, or the generic name Bennittites, in other than a wholly restricted sense, must err in both these respects. Let us now turn our attention briefly to two of the cycadeoid imprints and casts, which are quite as famous as the silicified trunks just discussed, and which supplement and add to our knowledge of the Cycadeoideae in such a remarkable manner,— namely Williamsonia and Anomocamites.