For what it's worth, I noted the shape of the seed's li'l 'ole when planting 2 horseflowers.
One was quite round, one was oval.
The oval became a male with a touch of purple on a few fanleaf stems, but none on the main stalk.
And the round 'ole seed jus' popped pistils but has the exact same coloration, or lack of same.
Looks like dis;
First, da kane. (male)

[attachment=o261900]

Den, da Wahine
Shorter, fatter, but same coloration, yah?;
[attachment=o261901]


"There are additional little indicators, like the parts I call the spurs. They seem to look more like crossed swords early in life whereas in males they just look like pointy things sticking up."

I'm thinking that the "crossed swords" thingie is more dependent on the diameter of the stem, which is in turn, affected by the speed of growth.
Males generally grow a li'l faster.
Faster growth will "skinny up" the stalk and cause the spurs to cross.
So, in a way, it is an indicator.
Aloha,
Weeze