E. susannae is another species with separate sexes. Your plant may be female and pollinated by another plant nearby. Watch those babies as they grow up!
The male parts on that plant seem to blow away with the slightest wind but the female parts should be pretty stable (and fall is flowering time). Interestingly E. susannae can produce offspring with E. bupleurifolia (the plant used to illustrate sexes above) and here's what one of those hybrids looks like. It appears to be sterile.
Sexing Euphorbias is complicated by the fact that male and female parts sometimes do not appear in synchrony. And the male parts tend to blow away in the wind (though the female parts tend not to). I was convinced both parents of my miniature leafy Euphorbias above were male (and was frustrated by that) until they started making fruit, and then I realized what was going on.
Another caveat is that the separation of the sexes is not iron clad, so male plants will sometimes make female flowers. Two examples of males walking on the wild side here.
So you know what to look for, this is what goes down on my E. flanaganii without me doing anything special. I don't collect the fruit any more so it just sits on the plant until it explodes or the wind takes it away. There may only be 1 or 2 seeds per fruit, and plenty of duds in there, but plenty of viable ones too.
I am having trouble loading the site below right now (and I see it's over a decade old) but it has (or had) a tremendous amount of useful information, including which Euphorbia species are dioecious (males and females are separate individuals).
http://euphorbia.de/indexe.htm
