the Dinosaurs (about 65 to 200 million years ago) the cycads were the dominant plants. So
you can imagine dinosaurs grazing on cycad seeds and roaming through cycad forests.
Figure 10.22: Cycads bear their pollen and seeds in cones on separate plants. ( 28 )Ginkgotrees, in the phylum Ginkgophyta, are unique because they are the only species
left in the phylum, although there are many other species in the fossil record that have gone
extinct (Figure10.23). Therefore, the Ginkgo tree is sometimes considered a “living fossil”.
The Ginkgo tree survived as it was widely cultivated in China, especially around Buddhist
temples. The Ginkgo tree is also a popular landscape tree today in American cities because
it is very tolerant of pollution. The Ginkgo tree, like the cycads, has separate female and
male plants. The male trees are usually preferred for landscaping because the seeds produced
by the female plants smell rather foul as they ripen.
TheGnetophytes,inthephylumGnetophyta, areaverysmallandunusualgroupofplants.
Ephedrais an important member of this group since this desert shrub produces the ephedrine
used to treat asthma and other conditions. Welwitschiaproduces extremely long leaves and
is found in the deserts of southwestern Africa (Figure10.24). Overall, there are about 70
different species in this very diverse phylum.
Angiosperms
Angiosperms,in the phylum Anthophyta, are the most successful phylum of plants and
vastly outnumber the individuals in other phyla (Figure10.25). The feature that distin-
guishes the angiosperms is the evolution of the flower, so they are also called the flowering
plants. Angiosperms inhabit a variety of environments; a water lily, an oak tree, and a barrel
cactus are all angiosperms.