MORPHOLOGY OF THE TRUNK AND DEVELOPMENT 
OF THE MICROSPORANGIUM OF CYCADS 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 
XCI 
FRANCES GRACE SMITH 
(WITH PLATE x) 
The original purpose of the investigation recorded in this paper 
was to secure as complete an account of the development of the 
microsporangium of cycads as possible, and especially to discover 
whether the archesporium is several-celled, as indicated by previous 
investigations. In securing staminate strobili at the earliest stage, 
attention was drawn to their successive appearance and the building up 
of the trunk, and the results of these observations have been included. 
The staminate strobili of Ceratozamia mexicana Brogn. (C. 
robusta Miq.) were obtained from the Botanical Gardens of Jena and 
Berlin, and also from Fairmount Park, Philadelphia. A strobilus 
of Encephalartos villosus was obtained from the Botanical Garden 
at Bonn; and most of the strobili of Zamia floridana were sent from 
Miami, Florida, in 1902, 1905, and 1906. No material of Ceratozamia 
was younger than the division of sporogenous cells just preceding 
the mother cells; and the material of Encephalartos showed sporangia 
about to shed the pollen. In Zamia the series is much more com- 
plete than in the other forms. Collections of staminate cones were 
sent from Miami every two or three weeks, from June 1 to September 
18, 1905; then less frequently up to the last of January, 1906, when 
pollination took place. In 1906 further collections of staminate 
and ovulate plants were made, at intervals of ten days, from June 5 
to September 1. These gave stages in the development of the strobili 
as well as of the sporangia. Only in Zamia floridana, therefore, 
has there been any attempt to study the early development of the 
sporangium or strobilus. The other genera have been used for 
comparison in the later stages of sporangium-development. 
I. Morphology of the trunk 
The cycads have a columnar or tuberous trunk, thickly covered 
with scale leaves and old leaf bases. Zamia floridana illustrates a 
187] [Botanical Gazette, vol. 43 
