A thornless variety inermis occurs. Cultivars selected and used for amenity planting are all thornless.

Thorny HLocusts sometimes decrease or even stop producing thorns as they reach maturity & growth slows down.

Also seems like there is a tendency for large, branching thorns to be a feature of the lower parts of the main trunk. If these are a response to terrestrial browers there wouldn't of course be much pressure to evolve thorns high up in the canopy.

Those Gleditsia of wild heritage have some of the most forbidding thorns of anything I've ever seen. And as with so many things, it seems that when the thorns were selected away from in creating cultivars, some other good qualities went away too. Those wild, thorny ones also seem to be larger-growing and less prone to canker diseases than such landscape staples as 'inermis', ie. "Skyline honeylocust.

There is an especially impressive one in one of our older parks. There are thorns down on the lower trunk that must be twelve inches in length, very stout and very sharp.

+oM

There are thornless varieties or cultivars of honey locust; also rooted cuttingÂs taken above the thorn line produce thornless trees. The honey locust is holdover from the ice age, the thorns were a defense against animals that could browse up to fifteen feet (mammoths, ground sloths, etcÂ), no animals exist today that can browse to that height. Above the fifteen the trees have no thorns. Ive seen thorn 18 inches long on some trees.

The North American analog to the parasol acacias of the African savannah.

The larger honey locusts around here have thorns far above 15'.

An 18" thorn would be impressive! The largest clusters I've noticed around here are probably around 6" to 8".

Here's a photo of a very longed thorned honey locust: http://www.flickr.com/photos/21734563@N04/3233243170/?edited=1

That's one mean looking tree; if the monster thorns don't kill you, the poison ivy will make you wish you were dead.

I have a honey locust that's either not a cultivar or is from a thornless cultivar that isn't true from seed, and thus has thorns. I've mostly just been clipping them back as they show up. However, does this present a risk to the tree of getting infections of nematode infestations or whatever else? Should I be putting something on the cuts?

No, cutting the thorns will not harm the tree.

I didn't know that the honey locust didn't grow thorns above 15ft so I checked out a few trees and sure enough it's true.