CYCADS. 



249 



Zamia than to Cycas. The genus Encephalartos is peculiar to 

 Africa, chiefly in the south, but some species are found within 

 the Tropics. In it the scales are peltate, and spirally arranged — 

 not in a linear series, as in the New World genera. 



In Australia we have Macrozamia with peltate scales also 

 spirally arranged. The scales have a drawn-out apex, sometimes 

 long enough to give an imbricated appearance to the cone. 



Alongside of these plants, characteristic of the regions where 

 they occur, there are remarkable aberrant genera. In Mexico we 

 find Dion, with perhaps three species. It has flat imbricated scales 

 in the cone. Stangeria, with its peculiar leaves and cones, is 

 found at Natal, in the geographical region of Encephalartos ; 

 and Bowenia, with its bipinnate leaves, in North Australia, the 

 country of Macrozamia. 



The geographical distribution of the Cycadeae is very interest- 

 ing, and extremely puzzling — more so than any group of plants 

 I know. The oldest group, like that found in the Lias, exists in 

 the islands and countries around the Indian Ocean, and forms 

 a very distinct subdivision of the order. The Zamias, in 

 which I include all the Cycads with their fruits in cones, have 

 one series represented by the genus Zamia, with the aberrant 

 Dion, confined to America ; a second series, represented by En- 

 cephalartos, with the aberrant Stangeria, in Southern Africa ; and 

 the third series, represented by Macrozamia, with the aberrant 

 Bowenia, in Australia. It is difficult for me, in accordance with 

 the generally accepted view of the origin of our existing vegeta- 

 tion, to imagine a common parent, of which no traces are known, 

 which gave origin in the Lias to a representative of the existing 

 genus Cycas, in the later Secondaries to the extinct Mantellias, 

 and Bennettites, and the existing Zamias, and which has left 

 well-marked and completely isolated genera peculiar to the great 

 divisions of the globe which possess a tropical climate — America, 

 Asia, Africa, and Australia. An order so well defined, with a 

 few well-limited genera, and not more than a hundred species, 

 supplies an advantageous group of plants to test theories of 

 geographical distribution or evolution. I cordially commend it 

 as a study to those engaged in such inquiries. 



I cannot venture before this audience to add anything about 

 the cultivation of these plants. As a rule they are not difficult 

 to cultivate. They have great stems, in which a large quantity 



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