Encyclopædia Britannica, Ninth Edition/Acotyledones

For works with similar titles, see Acotyledones.

​Acotyledones, the name given to one of the Classes of the Natural System of Botany, embracing flowerless plants, such as ferns, lycopods, horse-tails, mosses, liverworts, lichens, sea-weeds, and mushrooms. The name is derived from the character of the embryo, which has no cotyledon. Flowering plants have usually one or two cotyledons, that is, seed-leaves or seed-lobes connected with their embryo; while in flowerless plants the body representing the embryo consists of a cell, called a spore, without any leaves. The plants have no flowers, and their organs of reproduction are inconspicuous, hence they are called by Linnæus cryptogamous. Some flowering plants, such as dodders, have no cotyledons; and some have the cotyledons divided into more than two, as in conifers. Some acotyledonous spores, when sprouting, produce a leaf-like expansion called a prothallus, on which the organs of reproduction, consisting of antheridia and archegonia, are produced. This is well seen in the case of ferns. In the interior of the antheridian cells, moving filamentous bodies, called spermatozoids, have been observed. These fertilise the archegonial cells, whence new plants are produced. In the article Botany these plants will be noticed under Class III. of the Natural System.

This article is issued from Wikisource. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.