00:01
This is a question asking about the evolution of different traits in plants, particularly in land plants.
00:08
And it's asking for what kinds of traits evolved multiple times.
00:15
Lots of traits appear to evolve only one time.
00:19
And so those seem to be good features for helping us to define clades.
00:24
But some traits appear to evolve multiple times in the evolution of land plants.
00:31
And the one that's talked about that's most striking in this chapter is the evolution of heterospory.
00:41
So let's quickly just define our terms here.
00:45
If a plant is homosporus, it makes one kind of spore, and that spore grows up to be a gametophyte, and that gametophyte can make both male and female gametes eggs and sperm.
01:00
So you have one type of gametophyte.
01:08
And what that means is that often that gametophyte could self -fertilized.
01:14
That is the sperm from its anthraudia could swim to the eggs in its archagonia...