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.
(Japan, 1895); Ikeno, Untersuchungen uber die Entwickelting dec Geschlechtsorgane und den Vorgang der J3efruchtung bei Cycas revoluta, Jahr.
Cycads are represented by Cycas itself, which in several species ranges from southern India to Polynesia.
Bengal has no Cycas, oaks or nutmegs.
Apart from the occurrence of Cycas, the Asiatic character of the Polynesian flora is illustrated by the distribution of Meliaceae.
Of Cycads, Australia and New Caledonia have Cycas, and the former the endemic Macrozamia and Bowenia.
The flora consists of 129 species of angiosperms, i Cycas, 22 ferns, and a few mosses, lichens and fungi, 17 of which are endemic, while a considerable number - not specifically distinct - form local varieties nearly all presenting Indo-Malayan affinities, as do the single Cycas, the ferns and the cryptogams. As to its fauna, the island contains 319 species of animals-54 only being vertebrates-145 of which are endemic. A very remarkable distributional fact in regard to them, and one not yet fully explained, is that a large number show affinity with species in the Austro-Malayan rather than in the Indo-Malayan, their nearer, region.
A structure called the cool orchid house is set apart for the accommodation of the many lovely mountain species from South America and India, such as odontoglossums, masdevallias, &c., and in this the more uniform the temperature can be kept the better, that in summer varying between Cyanophyllum (Miconia) Cycas Dieffenbachia Dipladenia* Dracaena Eranthemum Eucharist Euphorbia Ficus Franciscea Gardenia Gesnera Gloriosa* Gloxinia f Heliconia f Hoffmannia I pomaea * Ixora Jacobinia Jasminum* Luculia Maranta Medinilla Meyenia Musa Nelumbium f Nepenthes Nymphaea f Oxera * Pancratium f Pandanus Passiflora* Pavetta Petraea * Pleroma* Poinsettia Rondeletia Sanchezia Schubertia* Scutellaria Stephanotis Tabernaemontana Terminalia Thunbergia Torenia Thyrsacanthus Tydaea Vinca Abutilon Acacia Agapanthus Agathaea Agave Alonsoa Aloysia Amaryllis Ardisia Asparagus Aspidistra Asystasia (Mackaya) Azalea Bauera Begonia Blandfordia Bomarea * Boronia Bougainvillea * Bouvardia Brugmansia Calceolaria Camellia Campanula Canna Celosia Cestrum * Chorizema* Chrysanthemum Cineraria 60° and 65°, and in winter from 45° to 60°.
In Cycas whorls of scales alternate with large pinnate leaves.
In the tropical zone large figs abound, Terminalia, Shorea (sal), laurels, many Leguminosae, Bombax, Artocarpus, bamboos and several palms, among which species of Calamus are remarkable, climbing over the largest trees; and this is the western limit of Cycas and Myristica (nutmeg).
Dioecious; flowers in the form of cones, except the female flowers of Cycas, which consist of a rosette of leaf-like carpels at the apex of the stem.
As a fairly typical and well-known example of the Cycadaceae, a species of the genus Cycas (e.g.
Of Cycas there is a well-defined alternation of transverse zones on the stem, consisting of: larger areas representing foliage-leaf bases, and similar but smaller areas formed by the bases of scale-leaves (F and S, fig.
In some species of Cycas the leaf-bases do not persist as a permanent covering to the stem, but the surface F F FIG.
Is covered with a wrinkled bark, as in Cycas siamensis, which has a stem of unusual form (fig.
In the genus Cycas the female flower is peculiar among cycads in consisting of a terminal crown of separate leaf-like carpels several inches in length; the apical portion of each carpellary leaf may be broadly triangular in form, and deeply dissected on the margins into narrow woolly appendages like rudimentary pinnae.
In Cycas the stem apex, after producing a cluster of carpellary leaves, continues to elongate and produces more budscales, which are afterwards pushed aside as a fresh crown of fronds is developed.
The young leaves of Cycas consist of a straight rachis bearing numerous linear pinnae, traversed by a single midrib; the pinnae are circinately coiled like the leaf of a fern (fig.
The male flower of Cycas conforms to the type of structure characteristic of the cycads, and consists of a long cone of numerous sporophylls bearing many oval pollen-sacs on their lower faces.
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.
The thick armour of petiole-bases enveloping the stem is a characteristic C y cad c an feature; in Cycas the alternation of scale-leaves and fronds is more clearly shown than in other cycads; in Encephalartos, Dioon, &e., From a photograph of a plant in the Peradeniya the persistent scale - leaf Gardens, Ceylon, by Professor R.
Another type of stem is illustrated by Stangeria and Zamia, also by a few forms of Cycas(fig.
An interesting species of Cycas, C.Micholitzua, has recently been described by Sir William Thiselton-Dyer from Annam, where it was collected by one of Messrs Sanders & Son's collectors, in which the pinnae instead of being of the usual simple type are FIG.
- Cycas siamensis.
The vernation varies in different genera; in Cycas the rachis is straight and the pinnae circinately coiled (fig.
In structure a cycadean sporangium recalls those of certain ferns (Marattiaceae, Osmundaceae and Schizaeaceae), but in the development of the spores there are certain peculiarities not met with among the Vascular Cryptogams. With the exception of Cycas, the female flowers are also in the form of cones, bearing numerous carpellary scales.
In Cycas revoluta and C. circinalis each leaf-like carpel may produce several laterally attached ovules, but in C. Normanbyana the carpel is shorter and the ovules are reduced to two; this latter type brings us nearer to the carpels of Dioon, in which the flower has the form of a cone, and the distal end of the carpels is longer and more leaf-like than in the other genera of the Zamieae, which are characterized by shorter carpels with thick peltate heads bearing two ovules on the morphologically lower surface.
He drew attention also to certain p roximal end of structural similarities between Cycas and Ginkgo.
This lateral course is due to the more vigorous growth of the axillary branch formed near the base of each flower, which is a terminal structure, and, except in the female flower of Cycas, puts a limit to the apical growth of the stem.
Short and reticulately-pitted tracheal cells, similar to tracheids, often occur in the circummedullary region of cycadean stems. In an old stem of Cycas, Encephalartos or Macrozamia the secondary wood consists of several rather unevenly concentric zones, while in some other genera it forms a continuous mass as in conifers and normal dicotyledons.
13, Pg) hangs down into the pollen-chamber; two large spirally ciliated spermatozoids are produced, their manner of development agreeing very closely with that of the corresponding cells in Cycas and Zamia.
The long linear leaves of some species of Podocarpus, in which the lamina is traversed by a single vein, recall the pinnae of Cycas; the branches of some Dacrydiums and other forms closely resemble those of lycopods; these superficial resemblances, both between different genera of conifers and between conifers and other plants, coupled with the usual occurrence of fossil coniferous twigs without cones attached to them, render the determination of extinct types a very unsatisfactory and frequently an impossible task.
The climbing species of Gnetum are characterized by the production of several concentric cylinders of secondary wood and bast, the additional cambium-rings being products of the pericycle, as in Cycas and Macrozamia.
(1897); Ikeno, " Untersuchungen fiber die Entwickelung, &c., bei Cycas revoluta," Journ.