This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
(Greek kukas, the name of a palm tree). Cycadaceae. Several beautiful palm-like plants, common in cultivation under glass. Plate XXXIII.
The Cycadaceae are of great interest because they occupy a place intermediate between flowering plants and the cryptogams. Like the former they have fruit with a large starchy endocarp; but like the latter their sexual prop, is accomplished by means of sperma-tozoids and archegonia, corresponding to the male and female elements in animals. The plants are dioecious; the male inn. is in the form of an erect cone composed of modified staminal leaves which bear on the under surface globose pollen sacs corresponding to microsporangia; the female infloresence consists of a tuft of spreading carpellary leaves having their margins coarsely notched; in the notches are situated the ovules, which are devoid of any protective covering, and correspond to macrosporangia. Pollination under natural conditions is effected by the wind. The pollen settles on the ovules and sends down a tube into the tissue of the nucellus. Archegonia are formed; egg-cells develop, and in the pollen-tube are produced spermatozoids provided with minute movable cilia by which they are propelled, very much as in the spermatozoa of animals. These are discharged over the archegonia and fecundate the egg.
The discovery of spermatozoids in the cycads was made by a Japanese student, S. Ikeno, while investigating the process of reproduction of Cycas circinalis. Those of Zamia, endemic in Fla., were described and figured by H. J. Webber, who found the mature spermatozoids of the latter genus to be the largest known to occur in any plant or animal.
Plate XXXIII. Cycas circinalis, the male plant.
Most of the species of Cycas are arborescent, having a trunk marked with rings of growth and with the scars of fallen petioles. The trunk is usually simple and columnar (though sometimes it is branched), and is elongated by a terminal bud. The pinnate leaves form a beautiful terminal crown like that of a palm or tree-fern. Cycads are found among the fossils of many geological formations, especially in those of the early Mesozoic. The latter formations are grouped together on this account, and the geological epoch which they represent is sometimes designated as the "Age of the Cycads."
Cycads are among the most ornamental plants of tropical and subtropical gardens. In the United States they are often designated "sago palms," although they have nothing in common with a palm except the general habit of growth. In Florida, according to H. Nehrling who has a plantation at Gotha, near the center of the state, they thrive equally well on high pine land and in the rich soil of the low hummocks. C. circinalis is apparently the most sturdy of the cultivated species. It is almost free from diseases; but it is more sensitive to cold than C. revoluta. The latter, on the other hand, is subject to diseases in low flat wooded situations. A third species, C. siamensis, which is comparatively rare, seems to be perfectly hardy in Florida. In cultivating cycads, Nehrling has attained the best results by keeping the weeds away from the base of the trees and loosening the soil from time to time, taking care not to injure the small network of tubercle-bearing roots surrounding the trunk. The tubercles, which are about the size of a pea, are interesting to the plant physiologist, and are apparently conducive to the plant's well-being. Nehrling gathers the pollen from the male plants and sprinkles it by hand over the female flowers to insure fertilization of the naked ovules.
Plants are propagated by seeds, which keep well for a month or more after ripening. According to E. N. Reasoner, they should be sown in shallow boxes or the greenhouse bench, lightly covered with sand, and after germination, potted off in small pots of moderately rich, light soil. The growing plants .do best in partial shade. The old plants frequently send up suckers around the base of the trunk. These may be taken off when in a dormant state and rooted, care being taken to remove the leaves to guard against excessive transpiration. Growing cycads require sunshine and moisture.
The beautiful glossy leaves of cycads are used in many countries for ornamenting temples and for decorating altars. On the island of Guam they are used for palm leaves on Palm Sunday, and in the early days they were carried by children in religious processions, marching from one village to another under the guidance of the Jesuit missionaries. Cycads are popular conservatory plants, of easy culture, and tenacious of life, even when neglected for a long time. Their stems deprived of leaves are easily transported in bulk and will soon resume growth when planted. In the southern United States, cycads are injured by frost but often revive after having apparently been killed.
a. Margins of pinnae flat. B. Modified fruit - bearing leaves (carpophylls) spinoustoothed along the margin.
c. Scales of male infloresence tapering into a long spine.
d. Leaves 5-8 feet long, with pinnae 10-12 in. long.