Gymnosperms

Abstract

They are a morphologically and geographically diverse assemblage of ancient cone-bearing woody seed plants of considerable ornamental and economic importance. In some cases, they may be threatened or endangered. These include four interesting subclasses (see table of extant gymnosperms): Cycadidae (cycads), Ginkgoidae (gingko), Pinidae (conifers), and Gnetidae (gnetums, etc.), Vast majority of conifers are common landscape plants in temperate as well as tropical climate regions. Gingko and most conifers, however, have also proven to be ideal economic and landscape plants, as well as subjects for bonsai specimens, and are used as such by many amateurs and in most conservatories. Species of the three genera, Gnetum spp., Welwitschia mirabilis, and Ephedra spp., are also seen primarily in botanical conservatories, but the first two are briefly mentioned and illustrated in this book to familiarize readers with their unusual and remarkable characteristics. Although extensive recent DNA studies have shown these genera to be related to other gymnosperms (Pinaceae), they share some features that are characteristics of angiosperms, hence they were considered by some to be the link between the two classes.