404 BOTANICAL GAZETTE [DECEMBER 
In March 1908 I visited southern Mexico to collect D. spinulosum. 
While on the way to Tuxtepec, I was informed that a plant which 
seemed to agree with my description, except that it was much taller, 
could be found near Tierra Blanca. In the mountains west and a 
little north of Tierra Blanca I found a few specimens and was told 
that plants were more numerous a few miles farther south. The 
information was correct, for on the immense hacienda of the Joliet 
Tropical Plantation Company, a short distance from Tierra Blanca 
and about 60 miles south of Vera Cruz, magnificent specimens are 
abundant. Mr. J.C. DENNIs, superintendent of the plantation, very 
generously furnished horses, guides, and the hospitality of his palatial 
home while I explored the mountains and secured photographs and 
material. The plant is usually well shaded, growing among the 
prevailing limestone rocks which have given name (Tierra Blanca) 
to the region. 
From Tuxtepec, a town on the Papaloapam River about forty miles 
southwest of Tierra Blanca, half a day’s ride on horseback brings one 
to the mountains where D. spinulosum is as abundant as at Tierra 
Blanca. In some places it is the only large plant, and it would not 
bean exaggeration to speak of a Dioon forest. Beautiful specimens, 
which might have been the pride of any conservatory, had been cut 
down to get the cones, because it was easier to cut the tree than to 
climb it. The natives use the young seeds in making éamales, as in 
D. edule, and at a later stage the dry stony seed coat is a common 
plaything for children. At Tuxtepec the dry seeds, each pierced with 
two holes, sell for fifteen cents a dozen. The Indians said that the 
plant extends some distance farther south, but that it does not occur 
on the western (Oaxaca) side of the mountains. 
Dioon spinulosum, with the exception of the Australian Cycas 
media, is the tallest cycad known, and its slender trunk with a large 
crown of leaves gives it the appearance of a palm (fig. 1). I measured 
specimens 12™ in height, and Drs. BARNES and LAND, visiting 
the Tierra Blanca region a few months after my return, found speci- 
mens more than 16™ in height, almost as high as the tallest known 
specimens of Cycas media. The slender trunk and graceful curve of 
leaves are in striking contrast with the stocky trunk and straight, rigid, 
ascending leaves of D. edule. 
