In Monoblepliaris, one of the lower Fungi, in some Algae, in the Vascular Cryptograms, in Cycads (Zamia and Cycas), and in Ginkgo, an isolated genus of Gymnosperms, the male cell is a motile spermatozoid with two or more cilia.
In the Characeae, the Vascular Cryptogams, in Zamia and Cycas, and in Ginkgo, the spermatozoids are more or less highly modified cells witi+m.-S, ~..
In the spermatozoids of Chara, Vascular Cryptogams, and in those of Cycas, Zamia and Ginkgo, the cilia arise from a centrosome-like body which is found on one side of the nucleus of the spermatozoid mother-cell.
Even in those cases where the cilia band, which is the product of the centrosome-like body or blepharoplast, enters the ovum, as in Zamia (c in fig.
Xxiv.; Webber, The Development of the Antherozoids of Zamia, Bot.
Amongst Cycads, Zamia is confined to the New World, and amongst Conifers, Araucaria, limited to the southern hemisphere, has scarcely less antiquity; Pinus reaches as far south as Cuba and Nicaragua.
- Stems tuberous or columnar, not infrequently branched, rarely epiphytic (Peruvian species of Zamia); fronds pinnate, bi-pinnate in the Australian genus Bowenia.
Zamia (South America, Florida, &c.).
- Like Zamia, except that the ends of the stamens are flat, while the apices of the carpels are peltate.
Branching, however, occurs not infrequently; in Cycas .the tall stem often p roduces several candelabra-like arms; in Zamia the main axis may break up near the base into several cylindrical branches; in species of Dioon (fig.
Another type of stem is illustrated by Stangeria and Zamia, also by a few forms of Cycas(fig.
3); in Encephalartos, Dioon, &c., both rachis and segments are straight; in Zamia the rachis is bent or slightly coiled, bearing straight pinnae.
Cases have been recorded (by Thiselton-Dyer in Encephalartos and by Wieland in Zamia) in which the short carpellary cone-scales exhibit a foliaceous form.
Similar spermatozoids were observed in some species of Zamia by H.
In Zamia floridana, the traces are described by Wieland in his recent monograph on American fossil cycads (Carnegie Institution Publications, 1906) as possessing a more direct course similar to that in Mesozoic genera.
(1900); Webber, " Development of the Antherozoids of Zamia," Bot.