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AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
distinctly tropic climates as present-day cycads. In accord with a world- 
wide distribution, a distribution exceeding that of cycads all the way from 
Florida to near the pole, the former had plasticity of both flower and leaf. 
Whether to be viewed as forerunners of the angiosperms or not, the 
Text Fig. i. Cycadeoidea Dartoni (?). Young frond deeply imbedded in the petiolar 
ramentum. The arrow shows the basal ears as in Otozamites. The two ranks of folded 
pinnules face the trunk axis. Finer hairs and histologic structure not conserved. Trans- 
verse thin section X 30. 
capacity to live in varied climates must be hypothesized. It is not, 
however, likely that the Dakota cycadeoids, fringing as they did more or 
less pure-stand forests of pines and araucarians, could have endured as 
severe a climate as that of the Argentine "stands" of Araucaria imbricata 
facing the dry treeless country to the west of the Patagonia plateau in 
south latitude 35°-38°. But with the young leafy crowns so thickly beset 
by ramentum and the fruits so enclosed by bracts and the armor, there was 
full protection from many degrees of frost and from a time of snow. 
Range of Large-stemmed Cycadeoids 
In North America, on the Atlantic-Gulf border, the evidence of an 
extended cycadeoid habitat is conclusive. Low down in the Potomac 
