132 Kansas Academy of Science. 



A RARE MEXICAN CYCAD. 



By W. B. Wilson, Ottawa University. 



'^pHROUGH the courtesy of Dr. C. J. Chamberlain, of the Uni- 

 -*- versity of Chicago, the writer is enabled to present to the 

 Academy for inspection an ovulate cone of the rare cycad Dioon 

 edule. 



The Dioon tree, which is a near relative of the so-called Sago 

 palm of our greenhouses, is found only in tropical Mexico, and 

 there in limited numbers. Little of a scientifio nature has been 

 written concerning it, recent publications in the Botanical Gazette 

 containing practically all that is authoritative on its morphology. 



In 1843, Lindley, of the Smithsonian Institution, found speci- 

 mens of this tree in the state of Vera Cruz, and listed them as Dioon 

 edule. All the Dioons were roughly classified under this species 

 until 1883, when Eichler described Dioon spinulosum, a few leaves 

 and a few trunks without leaves constituting his material. Dioon 

 purpusii was described by Purpus, in 1908, from a few specimens 

 which he collected in the state of Puebla, near Tomellin. 



Dioon edule is a small tree, reaching a height of only six or eight 

 feet, with trunk about four to six inches in diameter, bearing a 

 crown of leaves suggesting strongly in habit our Sago palm, or 

 Cycas revoluta. A new crop of leaves is produced every alternate 

 year, except those years when the tree goes into a resting state. 

 About twenty leaves, on an average, are put forth in a season, and 

 since the old leaf bases persist they furnish a valuable index to the 

 age of the tree. Conservative estimates fix the life period of a speci- 

 men five feet high, under normal conditions, at 1000 years. 



The natural habitat of Dioon edule is the open rocky stretches 

 and slopes of the southern Mexican mountains, where it is exposed 

 to the blazing tropical sunlight, though fine specimens are found 

 sometimes growing in sheltered canons, shaded by bushes and 

 small trees. The Mexican Southern and International railways 

 pass through the Dioo7i edule country. The best specimens have 

 been found on the International line near Chavarrillo, about fifteen 

 miles southeast of Jalapa. Dioon spinulosum is fairly abundant 

 near Tierra Blanca, sixty miles south of Vera Cruz. Doctor Cham- 

 berlain reports having seen magnificent specimens there, as well as 

 in the vicinity of Tuxtepec, forty miles southeast of Tierra Blanca. 



