The bullhorn acacia is kind of sad as acacias go. You know how most acacias produce alkaloids that taste nasty and keep things from eating them? Well, bullhorn acacias don’t. It’s like, get on the bus, bullhorn acacias.
Of course, bullhorn acacias are not hearing your noise, because they’re thinking outside the metabolically-expensive-poison box.
And what they’re thinking is that maybe if you like eating them, you’re really gonna like this face full of motherfucking ants they’ve got for you.
Yes, you read that right. Instead of playing fair and making their own toxins to keep everything and their brothers off of their leaves, this plant outsourced that shit to ants. Presumably this is because ants are easily bribed with food, generally looking for a fight, and, most importantly, can run really fast. Acacias in general, while also easily bribed and kind of ornery, are not known for their speed and mobility.
You’re probably looking at that picture and going “Man, I am just not seeing a real place for those ants to live. This plant is a terrible employer if it’s not even going to provide housing. Also, those thorns are kind of nasty-looking, but they’re awful big. I bet I could just avoid them and not step on the ant mound and be fine.” And this is not an unreasonable thing to think! Which is probably why the acacia already thought of it, and decided to keep its ant legions in its thorns.
Yup. This plant has evolved a way to shoot stinging insects out of its thorns, just in case stabbing you didn’t get the point across. This is because this plant is hardcore.
Now you may be sitting there going “I don’t know, ants are pretty metal, and that ant looks pretty metal even by ant standards. Maybe they just really liked the idea of living in hollowed-out thorns and did this all on their own.” And I can see why you’d say that, because it totally sounds like something ants would do, but you’d be tragically wrong. You know how some ants will properly farm or half-assedly shepherd aphids because they suck out plant juices and process and concentrate the sugars in their waste, which the ants then treat like gatorade?
The acacia tries to cut out the middle man there. They produce little bundles of protein and fat called Beltian bodies and then stick them on their leaflet tips, which is basically just mocking herbivores at this point, and then on the leaf stalks they’ve got these fancypants glands that produce nectar, to further rub it in. I mean, seriously. This plant is just hanging out going “Oh, yeah, my leafy greens taste like cake, assholes. You want this? Hope you like ants, too, because that’s what else is there.”
So the ants are getting a super fucking sweet deal here, and it’s like, man, this plant is going way out of its way to keep these sons of bitches around. Is it sure it wouldn’t be easier to just pony up with the alkaloids and taste gross? Because it seems like it wouldn’t be nearly so cool, but it would be way simpler than growing these ant apartments and ant cafeterias and whatnot, and this plant probably isn’t vain enough to evolve based on sheer coolness.
Well, ants aren’t stupid, but they are pretty fucking territorial. Remember how acacias are generally just not capable of getting up and wandering around? The ants do that for them. Any vines and shit trying to climb on the acacia get ant-murdered the same way herbivores trying to eat it get all face-stung, and the ants will go the extra distance of killing anything that tries to grow around the base of the tree. They send out fucking ant doom-patrols looking for weeds. And then they kill the shit out of them.
So, fucking bullhorn acacias, right? They really hit on a cool scheme. Surely they are the only plants that could pull this off. Nope! There’s a bunch of plants that have figured out how to make deals with ants, to the point where there’s a name for them: myrmecophytes. (“Myrmecophyte” is Greek for “Yo, dawg, there may have been a slight miscommunication after you said you liked plants.”). Some of them don’t even do anything for ants except make a nice living space, because that way when the ants die and start their little ant graveyards in random unused spaces, the plant can use their little tenant corpses as fertilizer. (Note: Do not trust plants. Ever.)