I've never heard of that. But I had to look it up. "Spinach has male and female plants, and, as you might expect, only the female plants produce seeds. In order to identify the female plants, look for round green balls under the leaves (male plants have yellow balls under their leaves)." uh huh, how interesting.
I had no idea. I found out recently the asparagus is male and female, so the male produces slightly more stalks than the female but the female produces seeds on the fronds. Hardly worth mentioning which is better or to cull or not to cull female asparagus which is, I guess, a thing.
Our onion plants have sent up stalks for flowers, for seeds, and we just hope they don't get broken by the rain or wind or hail, if that comes our way.