122 BOTANICAL GAZETTE [august 



older ones of the shaded forms, may be seen rings of the cortex and 

 bark which indicate the position of former terminal buds {iigs. 2, 4, 

 5i ^3 ^)' Just what these may signify relative to age has not been 

 determined. It may be that they are formed only by the foliage 

 buds, or only from scale buds, or even possibly from reproductive 

 buds, or all of these put together. It is not known how often a new 

 crown of scales, or of foliage leaves, or of reproductive structures is 

 formed in Microcycas. . These rings may persist until the plant is 

 quite old {-jig. 4), or may disappear entirely and give place to a bark- 

 formation quite resembling that of the trunk of some pines {fig. j). 

 In nearly all older plants at the base of the stem will be seen such 

 bark-formation as shown in the figure just cited, while at some point 

 above the characteristic rings appear. Were these characteristics 

 not found upon the same stem, one could readily believe that the 

 stems shown in figs. 2 and j do not belong to the same species. 



The details of anatomy of the stem have not been investigated. 

 From a gross examination it is evident, however, that Microcycas has a 

 single vascular cylinder surrounded by a thick cortex and enclosing a 

 large pith region {jig. 10)^ as in Zamia, Dioon, and Stangeria. The pith 



is extremely brittle, and its cells are densely filled with very large starch 

 grains. . 



The leaves, w^hich often exceed a meter in length, vary greatly 

 in the number in each crown {fgs. 1-8). The length of life of a leaf 

 could not be determined, and although no leaves upon old plants were 

 found opening from the bud, the vernation in seedlings is circinate. 



OVULATE CONES AND MEGASPORANGIA 



A single ovulate cone {jig. 8) was found on a number of plants. 

 It appears upon first observation to be a terminal structure, but closer 

 investigation indicates that it is lateral, though younger material must 

 be studied to determine definitely^ this point. The base of the cone 

 is enclosed by heavy, hairy scales {figs. 11 j 12) w^hich usually have 

 their upper ends pressed closely between the outer portions of the 

 basal sporophylls. The cone shown in jig. 8 was 94^"^ from the 

 center of its base to the center of its tip, and weighed 9 . 5^^, being the 

 largest cycad cone yet reported. This one, however, appears to be 

 slightly larger than the average ovulate cone of Microcycas. 



