Corn is a weird plant in a lot of ways, but one we don’t think about very much (because it is so obvious) is that a corn plant has entirely separate male and female reproductive structures: tassels and ears respectively.* This isn’t unheard of in the plant kingdom, but in the particular group of grasses corn belongs to (the Andropogoneae) it’s quite remarkable. Tripsacums, the closest relatives of corn outside of corn’s own genus (Zea), have separate male and female flowers, but those flowers still share a common reproductive structure with the male flowers at the tip and the female flowers at the base. I’d like to have a photo of my own to show you, but I won’t until the Tripsacum plants growing in our greenhouse flower this summer, so in the meantime, go look at this great photo someone else took.
But I bring this up to point out that the segregation of male and female flowers into entirely different parts of the corn plant is still a relatively recent, and fragile, evolutionary development, and it doesn’t take a lot to disrupt it. There’s a series of tasselseed mutants.** Stresses can do it. Various infections can do it. And sometimes corn plants, particularly tillers, just decide to be confusing.
*And no, don’t call sorghum heads (or panicles, it depends on how formal you feel like being) tassels.
**Why aren’t there just as many anther ear mutants? It could have to do with the way corn flowers are wired. If female floral organs start developing, they actually cause the male floral organs to die prematurely. But anther ear phenotypes still happen.***
***QTL Controlling Masculinization of Ear Tips in a Maize (Zea mays L.) Intraspecific Cross