Misconceptions about plants have more lives, and much longer lives, than a cat.The Phytophactor
Man sneezing in a canola/oil seed rape field.
A misunderstanding gets up his nose. Photo: Bigstockphoto

As AoB Blog’s non-botanist, I’m used to there being plenty of things I don’t know about plants. I’m usually good for a “Wow!” if anyone mentions that a line of plants has been around since the age of the dinosaurs, regardless of how many times I’m told this about plants. But there’s another problem. Sometimes I can learn a fact and be completely unhindered by any understanding of it.

An example is the post from the Phytophactor Pollen is not plant sperm. I should know this. I read about the alternation of generations when reading up about mosses, and pollen is a perfect example of this. I know some people reading will know almost as little about plants as me, so I’ll try to explain this below (or just demonstrate my misunderstanding) while botanists can skip to the next bit where I ask why should this be news?

Plant reproduction is weird

…or at least weird by human terms. Humans are dipolid. We have pairs of chromosomes. We produce a gamete which is haploid. These are cells that carry single chromosomes. They combine and make a new diploid human. So one diploid human produces another diploid human. Plants do not do this.

We’ll start by looking at angiosperms, flowering plants. Let’s imagine an oak tree. An oak tree is diploid, if we ignore the ones that aren’t. If pollen is sperm then we’d expect them to produce lots of the stuff and for some of it to fall on eggs to fertilise them. But when you look closely that’s not what happens.

Pollen is not a gamete.

It’s a spore. It grows into haploid pollen grain that can produce gametes, but it’s not just the gamete. The pollen travels to a pistile and develops a pollen tube to deliver the gametes. This can be quite complex. The seed is produced and this becomes a diploid plant that starts over again. Something like a tree that produces pollen and ovules is called a sporophyte because it produces spores as pollen or ovules. The pollen or ovule is called a gametophyte because they produce gametes.