A. _Cycas pectinata_, apex of megasporophyll. (¾ nat. size.) B, C. _Cycas Riuminiana_, megasporophyll. (¾ nat. size.) D. _Encephalartos Altensteinii._ Distal end of megasporophylls. (From the _Gardeners’ Chronicle_.) E, F. _Cycas angulata_, microsporophyll and sorus. G, I. _Ceratozamia mexicana_, I, microsporophyll with scars of sori (_s_); G, sorus. (After Thibout.) H. _Stangeria paradoxa_, megastrobilus.] [Illustration: Fig. 393. A. _Stangeria paradoxa_, part of microstrobilus. B, D. _Encephalartos villosus_, megastrobilus in surface-view and in section. (¼ nat. size.) C. _Ceratozamia mexicana_, single megasporophyll.] [Illustration: Fig. 394. _Macrozamia Preissii_, megastrobilus and (A) single megasporophyll; _a_, axis of cone; _p_, stalk of megasporophyll; _s_, unripe seeds. (After Rendle.)] [Illustration: Fig. 395. _Zamia floridana._ I_a_, complete plant; _a_, main trunk; _b_, branch-scar; _c_, secondary root; _d_, primary tap-root. (⅛ nat. size.) I_b_, I_c_, megastrobilus. (¼ nat. size.) I_d_, megasporophyll. (½ nat. size.) I_e_, pinna. (¾ nat. size. After Wieland.)] The microsporophylls (figs. 389, A; 392, E) are in all genera aggregated into strobili which often bear a close resemblance to seed-cones (fig. 393, A). On a single sporophyll of _Cycas circinalis_ there may be as many as 700 sporangia while in _Zamia floridana_ there are only two microsporangia. The spore-output is large and in extreme cases, _e.g._ in _Dioon spinulosum_, the average number of spores in a sporangium is said to be 30,000[61].