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VOLUME XLVIII NUMBER 6 
BOTANICAL (GAZETTE 
DECEMBER 1909 
DIOON SPINULOSUM ! 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY I 31 
CHARLES J. CHAMBERLAIN 
(WITH. SEVEN FIGURES) 
hice well-defined species of Dioon have been found in the Mexi- 
can tropics: D. edule Lindl., D. spinulosum Dyer, and D. Purpusti 
ose. LD, edule, which was described as early as 1843, is now quite 
well known. Although D. Purpusii was described only a few months 
ago, the species had often been seen, but had been mistaken for 
D. edule, which it resembles in its general appearance. I was told 
by a Mexican botanist that I should find D. edule along the Mexican 
Southern R.R. in the neighborhood of Santa Catarina, State of 
Oaxaca. He said there was no other cycad in that region. The — 
3 plant was easily found, and I at once saw that it was a new species 
intermediate between D. spinulosum and D. edule. The plant 
called D. edule in fig. tor of WIELAND’s American fossil cycads is 
the new D. Purpusii, as plainly indicated by the staminate cone and 
_ by the leaves. MacDovucat and Rose collected cones of the new 
_ Species in 1906 in the Tomellin cafion, where it was well shaded by 
bushes and small trees. Purpus in 1908 collected seeds and bracts in 
_ the Sierra Mixteca, Puebla. In April of the same year I saw the species 
at various places between Santa Catarina and Tomellin, growing in 
dry, exposed situations, associated with cactiand Beaucarnea. Rosk? 
describes the staminate sporophylls as “bracts with recurved ovate 
_ tips,” apparently supposing that the sporangia were borne on the 
sdipee a prosecuted with the aid of a grant from the Botanical Society of 
America 
2 RosE, J. N., Studies of Mexican and Central American plants. Contrib, U. S. 
Nat. Herb. 12: 259-302. 1909. 
401 
