so to clarify what's being talked about, "female" is a convenient way of saying 'produces large, stationary gametes (reproductive cells) in relatively small numbers,' and "male" is a convenient way of saying 'produces small, more motile gametes in relatively large numbers."
In plants, "pollen" contains male gametes but it is not "plant sperm." The way seed plant reproduction works is that basically the pollen grain is its own plant that has been extremely reduced in size, like cave fish losing their eyes but the pollen lost Everything and is basically just a little capsule for the "male" gametes.
This is because plants reproduce with alternation of generations, which is basically like if in order to have children, you and your partner each had to give birth to a special human capable of having sex, which would then create humans like you yourself.
You know how human sperm and egg cells have one set of chromosomes each—half as many as an adult human, which has (generally) two copies of every chromosome in every cell? Yeah, so instead of creating gametes directly, plants have always worked by basically having a whole child with only one set of chromosomes, whose purpose is to produce reproductive cells.
In the early evolutionary history of plants, both generations, the double-chromosomed Normal Form and the single-chromosomed Sex Having Form, have been entire independently living plants that could sometimes look very different from each other. However, in extant plants, one of the forms is very reduced and typically dependent on the parent plant. It's a male anglerfish kinda situation. And in flowering plants, it is particularly extreme, where the Sex Having Form is entirely reduced to either a few cells inside the flower ("female" gametes) or just a tiny grain of Dust That Fucks ("male" gametes).
We're not even getting into the plant genders yet.
In some plant species, individual plants are either male or female, but this is rare. Ginkgo is an example of a tree that has male or female trees. Male or female meaning they either produce "sperm" cells or "egg" cells. Plants that do this are called dioecious. (Plants that don't are called monoecious.)
Well...it's not that simple. In fact it's kind of dumb to call a whole plant male or female at all since the kind of "male" or "female" binary we think of as default is so rare, but that's a good place to start.
Flowers are reproductive organs of flowering plants. Are there male and female flowers then? Yes...sometimes, sort of. Oftentimes, flowers have both male and female "parts" in them at the same time, so they can produce pollen AND produce seeds. These flowers are called perfect or bisexual . In other cases, flowers are either "male" or "female," with only male or female "parts" instead of both in the same flower, and these flowers are called imperfect or unisexual.
So this means that some plants are dioecious and have imperfect flowers, and some plants are monoecious and have perfect flowers, right?
...wrong. It's way more complicated than that.
So let's go over all the possibilities for dioecious plants. I lied earlier. Dioecious plants have separate reproductive roles or "sexes" on different plants...but these "sexes" are not necessarily "male" and "female."
- "male" and "female" (dioecious. example: ginkgo)
- "male" and "both" (androdioecious. Example: Ginseng)
- "female" and "both" (gynodioecious. Example: Great blue lobelia)
- "male" AND "female" AND "both" (trioecious. example: Virginia strawberry)
HOWEVER...combine that with what we've just learned about flowers, and it gets way more complicated, because individual flowers themselves can be Male, Female, or Both...and an individual plant can produce any combination of these.
So, monoecious (opposite of dioecious) in the strict sense means a plant where all individuals produce "Male" flowers and "Female" flowers on the same plant. However, monoecious can also mean a plant species where all flowers are perfect/bisexual...or a plant where all individuals produce flowers that are Male, Female, AND bisexual...or a plant where all individuals produce flowers that are bisexual and male...and it keeps going.
And this is not even getting into situations where flowers transition from "male" to "female" or vice versa over time, or where whole plants do. (If I remember right, pawpaw is one of those plants where flowers transition from male to female.)
I'm not an expert, just a nerd. If anyone wants to add anything that would be really cool.
