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

  • George Reber Wieland
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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    my own point of view. But this line of inquiry is more appropriate to another chapter. Meantime, it seems extraor- dinary that the fossil before ns has received such scant notice in texts, and that just as if it had never existed, the correct- ness of Williamson’s restoration was so long called in question despite the added authority of Brongniart. (i) Anomozamites minor Nathorst.—The accurate descrip- tions of the original types given thirty years since by Nathorst, and more recently in his contribution on Einiye Mosozoischen Gycadophyten, leave little to add here, except by way of emphasis of the great botanical importance of this oldest of known cycadeoids. These specimens, still unfortunately few in number, are not only among the most priceless in the superb collections of fossil plants in the Natural History Museum at Stockholm, but deserve a foremost position amongst all fossil cycadophytes. In my American Fossil Cycads I have in unmistakable terms urged the great importance of Anomozamites, which by rea- son of its slender much branched stem, its small blade-like leaves, and its small fruits of Williamsonia type (apparently with 18 microsporophylls), is certainly more suggestive of rela- tionships to primitive Angiosperms, that is to the Magnoliacete as determined independently by both Hallier and myself, than is any other of the better known cycadeoids. Indeed the only possible contestant for this position of primary importance which can so far be suggested is Didyozamites. Because of its netted veined leaves, we may well suspect that this cycado- phyte, now known to be one of the cosmopolitan forms, may show yet closer approximations to Dicotyls—once we are for- tunate enough to find its fruits. For it need surprise no one if these should for instance exhibit that more primitive bispor- angiate combination of the Cycas-like, or multiovulate carpo- phyll, with reduced, microsporophylls. or stamens, which one may safely predict will be yet discovered in considerable variety amongst the cycadeoids.* * With the present additions, the known species of Cycadeoidean amphi- sporangiate flowers now number quite a dozen distributed in five more or less cosmopolitan genera, ranging through the entire Mesozoic, and ante- dating the angiosperms in the most suggestive manner as follows : 1. Anomozamites minor; Microsporophylls 17 or 18. —Trias. 2. Cycadella wyomingensis; i l 13 —U. Jura. 3. Cycadeoidea dacotensis ; i i 18 —Wealden. 4. etrusea; U — —L. Cretaceous (?). 5. ingens; l < 13 —Wealden. 6. Jenneyana; u 10 or 11. U 7. Paynei; l i i i 8. Reichenbachiana ; i l 16 u 9. Superba; < i — — “ 10. (Species); t ( il 11. Cycadocephalus Sewardi ; a 17 or 18. —Trias. 12. Williamsonia gigas• u 15 or 20. —Jura.
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