The President's Address. By D^tkinjield H. Scott. 131 



I will only refer to the Conifers in passing ; they are of much 

 interest to the botanist, who is naturally anxious to obtain evidence 

 as to the relative antiquity of the various constituent families, but 

 there is nothing sensational, as yet, about the Mesozoic Coniferse, 

 which, so far as our present very imperfect knowledge shows, did 

 not differ in any very striking way from the Araucarias, Pines and 

 Cypresses of our own time. 



We will concentrate our attention on the Cycad-like plants, or 

 Cycadophyta, to adopt the broader class-name, appropriately sug- 

 gested by Professor Nathorst. The living Cycadacete, of which 

 some account has been given on a previous occasion,* are, it will 

 be remembered, quite a small family, embracing only nine genera, 

 and, according to a recent estimate, about 100 species, inhabiting 

 the tropical or sub-tropical regions of both the old and new 

 worlds, but nowhere forming a dominant feature in the vegetation. 

 Throughout the Mesozoic period, however, at least until the Upper 

 Cretaceous is reached, plants with the habit and foliage of Cycads 

 are extraordinarily abundant, in all regions from which secondary 

 fossils have been obtained ; they are as characteristic of Mesozoic 

 vegetation as the Dicotyledons of our recent flora. In many 

 cases the fossil leaves closely simulate those of living genera 

 {Zy.7nites, Dioonites, Cycadites), others, such as Otozamites and A710- 

 mozamites, bear a more general resemblance to the Cycadean type 

 of foliage. Trunks, described under the names of Bucklandia, 

 Fittonia, and Yatcsia, recall vividly those of living genera ; in the 

 first -named form an alternation of the scars of foliage and scale 

 leaves lias been traced such as is found in Cycas at the present 

 day. The silicified stems, with structure preserved, confirm by 

 their anatomical characters the Cycadean relationship indicated by 

 the external features. Specimens of these various kinds are 

 characteristic of the Mesozoic floras in all parts of the world, and 

 there is thus a vast body of evidence for the abundance, during 

 that period, of plants showing Cycadean characters.! 



The most important point, however, in questions of affinity is 

 the fructification. Throughout the recent Cycads this is of a 

 simple type ; in all the genera the staminate fructification is a 

 cone, consisting of an axis densely beset with scales or sporophylls, 

 each sporophyll bearing on its lower surface a number — often a 

 very large number — of pollen-sacs, grouped, like the sporangia of 

 a fern, in small sori. In eight out of the nine genera the female 

 fructification is also strobiloid, each sporophyll bearing two marginal 

 ovules. In the Mexican genus Dioon the scales of the cone are 

 much expanded and have a somewhat foliaceous character. In 

 Cycas itself, however, so far as the female plant is concerned, we 



* See this Journal, 1905, p. 148. 



t See A. C. Seward, Address to Botanical Section, British Association Report 

 for 1903. 



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