Cycas

“ In Cycas, however, no female cone is produced, but the leaf-like carpels, bearing from two to six ovules each, are borne directly on the main stem of the plant in rosettes alternating with those of the ordinary leaves—the most primitive arrangement known in any living seed-plant. ”

“ Ferns, Equisetaceæ, and Lycopodiaceæ. In our actual vegetation, Coniferæ and Cycadeæ scarcely compose a three hundredth part. [45]
The family of Cycadeæ comprehends only two living Genera; viz. Cycas, (Pl. 58.) and Zamia. (Pl. 59.) There are five known living Species of Cycas and about seventeen of Zamia. Not a single species of the Cycadeæ grows at the present time in Europe; their principal localities are parts of equinoctial America, the West Indies, the Cape of Good Hope, Madagascar, India, the Molucca Islands, Japan, China, and New Holland. ”

“ 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. From the lower part of a carpel are produced several laterally placed ovules, which become bright red or orange on ripening ”

“ Cyrus Harding and Herbert, after having examined that part of the Far West where the cycas grew, took their bearings, and returned to Granite House, where they made known their discovery.
The next day the settlers went to collect some, and returned to Granite House with an ample supply of cycas stems. The engineer constructed a press, with which to extract the mucilaginous juice mingled with the fecula, and he obtained a large quantity of flour, which Neb soon transformed into cakes and puddings. ”

“ The Cycas revoluta figured in Pl. 58 [54] possesses a peculiar interest in relation to both our fossil species, in consequence of its protruding a series of buds from the axillæ of many of the scales around its trunk. These buds explain analogous appearances at the axillae of many fossil scales on Cycadites megalophyllus, and Cycadites microphyllus (see Pl. 60, Fig. 1, and Pl. 61, Fig. 1,) and form an important point of agreement in the Physiology of the living and fossil Cycadeæ. ”

“ 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. Seeds albuminous, with one integument; the single embryo, usually bearing two partially fused cotyledons, is attached to a long tangled suspensor. Stems and roots increase in diameter by secondary thickening, the secondary wood being produced by one cambium or developed from successive cambium-rings.
The cycads constitute a homogeneous group of a few living members confined to tropical and sub-tropical regions. ”

“ However different a boyau may seem to many, yet when viewed in conjunction with Cycadeæ, the graduation to the present case becomes natural, and even the resemblance may be perfect, because in Cycas the grains of pollen get into the nucleus bodily, although they would still seem to throw out short tails.
Wonderful is the simplicity of nature! The male organ in its essence, consists of a single cell containing molecular matter. ”

“ Female flowers are wanting in Cycas, because the carpels do not terminate the apical growth of the stem. After a group of foliage-and of scale-leaves, a group of carpels is developed, which are pinnate and resemble the foliage-leaves, bearing on their edges a number of ovules (most frequently [254] 5–6) (Figs. 245, 256) ; the same stem produces successively scale-leaves, foliage-leaves, and carpels. The differentiation is not much more advanced than in certain Ferns (Struthiopteris, Blechnum) , where barren and fertile leaves of different form regularly alternate. ”

“ The Gymnosperms comprise only trees or shrubs. The flowers are always unisexual and destitute of perianth (except Gnetaceæ) ; the female plant of Cycas is the only one which has no flower. The MALE FLOWERS are constructed on the same type as the cones of the Horsetails and Club-Mosses, and are most frequently long shoots (Figs. 243, 258, 260 A, 267 J) bearing a number of spiral or verticillate stamens. ”

“ Similarly, the dead fronds fall off, leaving a ragged petiole, which is afterwards separated from the stem by an absciss-layer a short distance above the base. In some species of Cycas the leaf-bases do not persist as a permanent covering to the stem, but the surface 755 is covered with a wrinkled bark, as in Cycas siamensis, which has a stem of unusual form (fig. 2) . Small tuberous shoots, comparable on a large scale with the bulbils of Lycopodium Selago, are occasionally produced in the axils of some of the persistent leaf-bases ”

“ The bark of the young shoots is much employed in medicine.
156. Cycas revoluta.—The sago palm of gardens. The stem of the plants abounds in starch, which is highly esteemed in Japan. A gum exudes from the trunk of the old plant, which is employed medicinally by the natives of India.
157. Cycas circinalis.—A native of Malabar, where a kind of sago is prepared from the seeds, which are dried and powdered; medicinal properties are also attributed to the seeds. ”

“ The morphology of the male sporophyll of Cycas, however, presents a great difficulty, and Brown, less fortunate here, discusses a number of what seemed to him possible explanations. The recognition of Sporangia was remote, and the effort [119] to homologise the numerous pollen sacs either to grains of pollen which, bursting, liberated fovilla, or to male flowers, or to explain them in other ways, was not very successful. The fact is this was a piece of morphology for which the age was not ready. ”

“ He drew attention also to certain structural similarities between Cycas and Ginkgo. The main anatomical features of a cycad stem may be summarized as follows: the centre is occupied by a large parenchymatous pith traversed by numerous secretory canals, and in some genera by cauline vascular bundles (e.g. Encephalartos and Macrozamia) . In addition to these cauline strands (confined to the stem and not connected with the leaves) , collateral bundles are often met with in the pith, which form the vascular supply of terminal flowers borne at intervals on the apex of the stem. ”

“ One of the most important discoveries made during the latter part of the 19th century was that by Ikeno, a Japanese botanist, who first demonstrated the existence of motile male cells in the genus Cycas. Similar spermatozoids were observed in some species of Zamia by H. J. Webber, and more recent work enables us to assume that all cycads produce ciliated male gametes. Before following the growth of the pollen-grain after pollination, we will briefly describe the structure of a cycadean ovule. An ovule consists of a conical nucellus surrounded by a single integument. ”

“ The Cycas disappeared as we receded from the river. We passed a small scrubby creek, and a long tract of stringy-bark forest, mixed with bloodwood and Pandanus, and patches of Cypress pine. Here we again observed the gum-tree with orange blossoms and large ribbed seed-vessels, which we found at the upper Lynd, and had called Melaleuca gum. Sterculia was frequent, and we collected a great quantity of its ripe seeds. We passed several dry swamps, surrounded with tea-tree thickets, and heaps of fresh water mussel shells. A rich iron-stone rock cropped out frequently ”

“ Classification.—A. Cycadeae.—Characterized by (a) the alternation of scale- and foliage-leaves (fig. 1) on the branched or unbranched stem; (b) the growth of the main stem through the female flower; (c) the presence of a prominent single vein in the linear pinnae; (d) the structure of the female flower, which is peculiar in not having the form of a cone, but consists of numerous independent carpels, each of which bears two or more lateral ovules. Represented by a single genus, Cycas. ”

“ 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. These concentric rings of secondary xylem and phloem (fig. 9) afford a characteristic cycadean feature. After the cambium has been active for some time producing secondary xylem and phloem, the latter consisting of sieve-tubes, phloem-parenchyma and frequently thick-walled fibres, a second cambium is developed in the pericycle ”

“ Cocus————, or small white scaly insect, which generally infests Cycas revolùta and circinàlis, the varieties of Nèrium oleánder, Oleas, and several species of Acacias, may be destroyed by washing as above with a sponge, and a strong decoction of tobacco, using the liquid about the warmth of 100°. Being thus heated, it irritates the insect, when, by easing itself from its bed, the fluid passes under it, and causes immediate death. If it is not thus irritated, it adheres so closely to the foliage, that it will keep you at defiance. ”

“ But the analogy of the female spadix of Cycas to that of Zamia is sufficiently obvious; and from the spadix of Zamia to the fruit-bearing squama of Coniferæ, strictly so called, namely, of Agathis or Dammara, Cunninghamia, Pinus, and even Araucaria, the transition is not difficult. This view is applicable, though less manifestly, also to Cupressinæ; and might even be extended to Podocarpus and Dacrydium. But the structure of these two genera admits likewise of another explanation, to which I have already adverted. ”

“ The stems of cycads are often described as unbranched; it is true that in comparison with conifers, in which the numerous branches, springing from the main stem, give a characteristic form to the tree, the tuberous or columnar stem of the Cycadaceae Stem and leaf. constitutes a striking distinguishing feature. Branching, however, occurs not infrequently: in Cycas the tall stem often produces several candelabra-like arms; in Zamia the main axis may break up near the base into several cylindrical branches; in species of Dioon (fig. 4) lateral branches are occasionally produced. ”

“ We found the fruit then ripe, and exhibiting a most magnificent spectacle. The plant was much larger than any I had seen of the same species, and seems to be one of the oldest in England. We learn from the Hortus Kewensis that this Cycas has been about 40 years in our collections. It is not known that the Farnham plant was larger at its first introduction than such as are usually brought from abroad, perhaps 2 or 3 feet in the diameter of the circle formed by the expanded leaves; that diameter is now 10 or 12 feet. ”

“ After pollination the pollen-tube grows into the nucellar tissue, as in cycads, and the pollen-grain itself (fig. 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. After fertilization the ovum-nucleus divides and cell-formation proceeds rapidly, especially in the lower part of the ovum, in which the cotyledon and axis of the embryo are differentiated; the long, tangled suspensor of the cycadean embryo is not found in Ginkgo. ”

“ Another type of stem is illustrated by Stangeria and Zamia, also by a few forms of Cycas (fig. 2) , in which the fronds fall off completely, leaving a comparatively smooth stem. The Cyas type of frond, except as regards the presence of a midrib in each pinna, characterizes the cycads generally, except Bowenia and Stangeria. In the monotypic genus Bowenia the large fronds, borne singly on the short and thick stem, are bi-pinnate (fig. 5) ; the segments, which are broadly ovate or rhomboidal, have several forked spreading veins, and resemble the large pinnules of some species of Adiantum. ”

“ Beautiful Cycas palms are also common, with Terminalia, Bignonia, Sterculia, dwarf Phœnix palm, and Gurjun trees. The east slope of the mountain is damper, and much more densely wooded; we there found two wild species of nutmeg trees, whose wood is full of a brown acrid oil, seven palms, tree-ferns, and many other kinds of ferns, several kinds of oak, Dracæna, and figs. The top is 1,136 feet above the sea, and commands an extensive view to all points of the compass ”

“ Araucaria to the first and last. Of Cycads, Australia and New Caledonia have Cycas, and the former the endemic Macrozamia and Bowenia. The Australian land-surface must be of great antiquity, possibly Jurassic, and its isolation scarcely less ancient. In Lower Eocene times its flora appears to have been distinctly related to the existing one. Little confidence can, however, be placed in the identification of Proteaceous or, indeed, of any distinctively Australian plants in Tertiary deposits in the northern hemisphere. The Australian flora has extensions at high levels in the tropics ”

“ The third or “adaptive” group comprises many of the characteristic littoral trees and shrubs of the Pacific islands, such as Barringtonia speciosa, Guettarda speciosa, Terminalia katappa, Tournefortia argentea, &c., that contain in their fruit-coverings a buoyant cork-like material often bound together by fibres, but which proves on examination to resemble cork only in appearance. In another type, illustrated by the fruits of Cycas circinalis and the seeds of Anona paludosa, the buoyant tissue forms a layer inside the shell of the seed or “stone.” ”

“ In the Notulae numerous species are described and figured nearly always with reference to the morphology and physiology of the parts concerned. It is his investigations made with direct reference to morphology and reproduction that claim our attention most. In dealing with them it is convenient to treat of the main questions to which he directed his attention rather than of the separate papers. I shall call attention first to his work on the flower and on fertilisation in a number of plants, then to his observations on Cycas, and lastly to his work on the Cryptogams. ”