On the nature of pappus

I need to correct a mistake in last night's post.  I called the Coyote Brush flowers male, but I've realized now that the flowers in last night's photo are female (and I've corrected that post).

I'm not a botanist, so I hope you will forgive my mistake...and perhaps you can learn with me.  Here's what happened.  I had remembered that in Coyote Brush, male and female flowers occur on separate plants.  But when I took the picture that I showed last night, I couldn't remember how to tell the different types of flowers apart.  So I looked around for clues and found this:

 

I said, "Okay, I can see that the shorter yellowish flowers are producing pappus."  Pappus is the white fluffy material that (often) carries seeds.  [When you blow seeds off a dandelion, you're blowing on the pappus (with a seed at the bottom) which then floats away.]  

Until now, I have associated pappus with seeds, which are produced by female flowers, so I thought these shorter yellowish flowers were female.  And I reasoned that therefore the longer whitish flowers (in last night's photo) were male.

Then today I noticed a lot of insect activity around some Coyote Brush plants — e.g., here's a nice fly (and an ant), feeding on white flowers.

 

When I looked closely, I realized that there was pappus associated with the white flowers (see below for an example):

 

So now I realized I had a problem.  A few days ago I had noticed pappus on yellow flowers, and today I observed pappus on white flowers.  So...which flowers are male and which are female?

I had to do some more research, and discovered that the white flowers are female and the yellow flowers are male.  They *both* produce pappus, but note that the pappus is longer in the females and shorter in the males.

I hadn't realized that some male flowers produce pappus, but now I know, and you do, too! 

Since pappus is associated with seeds and can play a role in seed dispersal, it raises the question of why male flowers also produce pappus?  I don't know the answer, but let me know if you've heard of an explanation (or can think of one!).

Here are two more pictures: a closeup of male Coyote Brush flowers, and a handsome striped fly on a male flower: