Chapter 14: Plants and Fungi
Many biologists, including me, are a little puzzled by the inclusion of fungi and plants
together in a single chapter, especially when you read (on page 277) the statement that
fungi are more evolutionarily related to animals than plants.
Figure 14.3 is very important to you, it neatly encapsulates a general lifecycle,
and is key to your understanding that all plants show an alternation of generations - a
term that refers to the fact that there are two distinct life forms of all plants, and these
distinct forms generate each other. The gametophyte form is haploid, and it
makes gametes - the egg and the sperm, via mitosis. The sporophyte form is diploid and
it produces spores via meiosis. In some of the more evolutionarily primitive plants such
as ferns, there are actually physically separate gametophytes and sporophytes, the fern
gametophyte is a tiny little green plant that produces sperm and eggs, and when these
unite (eggs from one gametophyte unite with sperm from another gametophyte) a
fertilized cell called a zygote forms that then grows to form the large leafy fern
sporophyte that you are familiar with.
In advanced plants, like the flowering plants, the sporophyte is dominant, it is much
larger than the gametophyte - which is much reduced in size and consists of the
reproductive parts in the flowers.
(Don't memorize the specific life cycle diagrams that are given for mosses a