Stuff I shoulda known

[urbpan]

Just heard a snippet of a Robert Krulwich piece on NPR that made me dash to the computer to check out the full story.

One of the guaranteed species on an Urban Nature Walk is the honey locust. It's a widely planted, pollution tolerant tree, with tiny leaflets that blow away in the fall requiring little clean-up. Most of the honey locusts found in cities are cultivated varieties that have done away with their two most interesting features. First, their huge seed pods, and second, their array of large sharp thorns:



I'd been walking around with the misapprehension that this tree was native to the hills south and west of here, but apparently that applies only to black locust.  Honey locust is considered native, and for the purposes of Krulwich's piece, was known to be growing on Manhattan Island 13,000 years ago.  Also on Manhattan at that time, were elephants, specifically mastodons.  Now for the honey locust tree to evolve these big, sharp, and expensive (from a biological point of view--that's a lot of energy to devote to a decoration) thorns, there had to be some animal that the tree wanted to deter.  I always assumed that the thorns were there to slow down raccoons and bears from climbing the tree to eat the seed pods before they were ready.  Krulwich proposes that the thorns, which come out of the bark of the trunk as well as the branches, evolved to keep some herbivore from stripping the bark.  He points out that the acacia tree of Africa, which famously still has elephants, bears similar thorns.  He also mentions that until someone studies mastodon droppings or coprolites and finds honey locust parts therein, there is no proof that mastodons ate from the honey locust.

Pretty cool.  Of course my contrary side would quickly like to mention that there are other bark-eating animals in Northeastern North America that haven't gone extinct.  Moose and white-tailed deer come to mind, not to mention the cottontails.  But it's so fun to picture mastodons in New York and New England that I'll play along for a while.

Comments

[buboniclou.livejournal.com]

Awesome! Of course, the thorns don't deter squirrels. They like to steal the seed pods, which reportedly taste like vanilla. Squirrel candy!

I knew they'd found mastodon teeth on Long Island before, but I guess I always figured our honey locusts, like so many other street trees, were an import. Thanks for the post, I <3 Krulwich.

[urb-banal.livejournal.com]

heh, you don't say, heh, umm interesting.

[mellawyrden.livejournal.com]

We have those all over campus at Binghamton Univesity. Apparently, at some point, students' parents complained that the thorns might be dangerous (should one of their precious children drunkenly blunder into one of the trees some night, or skateboard into them...). University landscapers have to go round and trim the thorns from the locust trees regularly.. and I gather them all up, to make sculptures out of them. They're SHARP! Some of the thorns are as long as fingers!

[mellawyrden.livejournal.com]

and actually, I don't think there's extra energy devoted to the development of these thorns... because I think they eventually grow into branches. You can see how they start branching out, the bigger they get. That was always my impression.

[harrietbrown.livejournal.com]

I just have this image of mastodons trotting down Fifth Avenue, trunks raised high, trumpeting loudly to hail a cab ... must be the wine and Coke ...

[wirrrn.livejournal.com]

Now *that* is a thorn!! *g*

I'm sure there are plenty of North American animals it could have used the thorns against- beavers, bears etc. As for prehistory, weren't there giant ground sloths in the US of A at one point?

[urbpan.livejournal.com]

It's possible. Apparently Megalonyx sloths roamed very far north from their South American origins.

http://en.wikipedia.org/wiki/Megalonyx

[agelena.livejournal.com]

There's one that arches over my driveway, so I'm constantly on the lookout for broken twigs with the killer thorns on them, hoping to get to them before my tires do.

[brush-rat.livejournal.com]

I've got a story in tuesday's paper about a huge paleological site in the valley dating from when it was a marsh. We had non-wooly mammoths here, as well as camels, sloths, sand American lions, which could totally have kicked ass on those puny African lions.

[urb-banal.livejournal.com]

i just re read your entry. i have no other source for such amazing info. thank you for all your posts.

[urbpan.livejournal.com]

You're Welcome!

[http://users.livejournal.com/_bazilisk_/]

A rogue historian tried to convince the crowd that I was in that Broadway, built on top of a "cowpath"/ deer trail, was not a mere deer-trail-turned-human-path-turned-horse-and-buggy-path-turned-paved-road but rather one that started with MASTADONS. I like the idea of giant herds of giant elephants stampeding, carving out this slightly random trajectory that curves below Houston street, turning NY's perfect grid into a rather confusing mess, more than mere deer politely, orderly, prancing through the forest.

[(Anonymous)]

I don't think that the existence of anti-girding thorns on honey locusts is posited as a reason for the disappearance of mastadons from North America. It is simply another piece of circumstantial evidence (a pretty cool one) that they were a well established part of the ecosystem (which we're pretty sure of anyway given the relative ubiquity of their remains throughout the continent).

It's pretty wild to imagine what North America was like until just several thousand years ago, when most of the megafauna was still here - mastadons, wooly mammoths, giant ground sloths, saber-tooths, camels, zebras, cheetahs, lions... Wow!

Btw (anal-retentive-hat-on), current understanding is that mastadons were not elephants or even elephant-ancestors - they were distant cousins, belonging to an entirely different Family (a taxonomic distance similar to that between us humans and gibbons).

[urbpan.livejournal.com]

I don't think that the existence of anti-girding thorns on honey locusts is posited as a reason for the disappearance of mastadons from North America.

I don't believe anyone said that...?

As far as I'm concerned, foxes are dogs, humans are apes, spiders are bugs, and zebras are horses. You know what they say about people who wear anal retentive hats!

[(Anonymous)]

I guess I misread this bit:

Of course my contrary side would quickly like to mention that there are other bark-eating animals in Northeastern North America that haven't gone extinct.

...my bad.