62 GYMNOSPERMS 



THE WESTERN CYCADS 



Two of the western genera, Dioon and Ceratozamia, are entirely 

 confined to Mexico, and Zamia is abundant there. Microcycas is 

 found only in western Cuba; but here, again, Zamia is abundant. 



The cycads grow so luxuriantly in most tropical and subtropical 

 regions that they are popular decorative plants on lawns and in 

 patios. Consequently, people who write from hearsay, without actu- 

 ally visiting the localities, may greatly increase the range of a plant. 



Dioon cdule. — The finest station for Dioon cdule is at Chavarrillo, 

 15 miles east of Jalapa (fig. 54). It grows in the blazing sun, asso- 

 ciated with small cacti, small acacias, bromeliads, and small oaks 

 30-60 cm. in height. Although plants are abundant and cone freely, 

 the patch does not seem to be spreading. 



Farther down the line, at Palmar and Colorado, there is another 

 large stand; but there does not seem to be any extension beyond 

 Rinconada. There are plants at Huatusco, south of Jalapa; and at 

 Rascon, between San Luis Potosi and Tampico, Dioon cdule is so 

 abundant that many cattle die from eating the poisonous leaves. It 

 has also been reported, probably correctly, as growing in rocky places 

 in the states of San Luis Potosi, Nuevo Leon, and Tamaulipas. There 

 are doubtless many other stations, but any reports not coming from 

 experienced botanists should be checked, because the plant is so 

 often used to decorate the patio. 



Dioon spinidosum. — Dioon spimdosum grows much farther south 

 than D. edide, appearing first about 55 miles south of Vera Cruz, and 

 becoming more abundant southward (fig. 55). On the Hacienda de 

 Joliet, near Tierra Blanca, there are hundreds of large plants, some 

 of them 10-16 meters in height. South of Tuxtepec, about 100 miles 

 south of Vera Cruz, there are forests of this species. Since it is very 

 popular as a decorative plant, any reports of its geographic distribu- 

 tion sfiould be confirmed. In the first two localities from which I 

 obtained material, the plants were nursery specimens. The plant 

 does not occur, except as a nursery specimen, in either of the two 

 localities mentioned in the original descriptions. 



Dioon purpusii. — This comparatively new species has a much 

 more restricted range. It is found near the railroad at Santa Cata- 

 rina; also in the Tomellin Canyon, north of Oaxaca, and in the Sierra 



