Living Pleistocene Fossil

[ashcraft]

A while back I put some info on hedgeapples in another thread, which generated some interest, so here is another iceage survivor, the honey locust. The honey locust, Gleditsia triacanthos is an early invasive species here in Missouri, and actually makes a very nice tree- except for the thorns. These thorns appear to have no apparent function, so why are they there? They are probably an adaptive response to the large pleistocene animals, particularly mastodons, who may have tried to push the tree over to get at the sweet fruit pods as they ripen. Trees with thorns didn't get pushed over by elephants, so they lived longer, so they produced more offspring, which tend to look like their parents.

The tree is also interesting in that it is a legume, a group of plants that symbiotically live with nitrogen fixing bacteria, giving them an advantage in poor soil locality where nitrogen is the limiting nutrient. Other legumes include beans, peas, and clover. Other trees would include the Red Bud.

Trees are not a natural group, meaning that trees are not necessarily closely related. Many plants have experimented with gigantism, which we think of as trees, but they are not necessarily closely related. The Fern Trees come immediatly to mind, but other plants also have trees. Monocots, which are the group that contains the grasses have experimented with trees, the most commonly thought of is the palm, but grass has also grown its tree-like member, which we call bamboo.

School starts Thursday, just trying to get back into the swing of things.

Brent Ashcraft

[tracer]

that's very interesting, and not something that i ever would have thought of intuitively, sooo....cool!

[grandpa]

Great stuff, Brent. Keep it coming.

[MikeD]

oooooh, I remember a few encounters with those as a kid.

[Nicholas]

Nice specimens, I really like living fossil flora.

[Traviscounty]

Reminds me of a cross between a Mesquite Tree and one we used to call "Tickle Tounge". You could cut off a patch underneath a thorn, and it would numb your tongue. I'm not quite sure why we used to do that.

[Auspex]

Your honey locusts are a lot spinier than ours in the mid-Atlantic! Ours do not have thorns on the trunks (at least on the ones bigger than sapling).

Not getting pushed over is a good strategy, but they still relied on mammals for seed dispersal, so should "want" them to be swallowed by something big enough to do so, but which was not equipped to grind the seeds in the pod. Ground-feeders, maybe?

[ashcraft]

Your honey locusts are a lot spinier than ours in the mid-Atlantic! Ours do not have thorns on the trunks (at least on the ones bigger than sapling).

Not getting pushed over is a good strategy, but they still relied on mammals for seed dispersal, so should "want" them to be swallowed by something big enough to do so, but which was not equipped to grind the seeds in the pod. Ground-feeders, maybe?

We have honey locusts that are thornless, they are often planted by nurseries because they make such a nice tree, sans thorns. These are some of the thornier that I have seen, and are right on the edge of the woods, maybe sunshine on the trunk encourages growth? Everything eats the pods, and I assume people have too to say they taste like honey. This is probably why they are still so widespread, with many vectors of dispersion, whereas the hedgeapple became too specialized, relying on large animals only for dispersion. Specialization always leads to extinction.

It has two close relatives, the water locust, which is distinguishable by its fruit, and the fact it tends to grow in swamps, and the black locust, which isn't quite as thorny. The black locust has rot-resistant wood, and so was often used for fence posts, which would then take root and turn back into trees. The black locust also makes great firewood, if you can get by the thorns, because it has extremly high BTU value.

Brent Ashcraft

[MarkGelbart]

I corresponded with Dr. Saunders of the Illinois State Museum about a paper he wrote in the early 1990's. He was with a group of scientists who studied several Pleistocene fossil sites in southern Missouri which are now flooded by Truman Lake. Apparently, during the Pleistocene there were artesian springs in the region that attracted mastodons. There were lots of plant macrofossils that showed the change in the environment from a broad-leafed forest, 50,000 years ago to an open jack pine parkland forest 30,000 years ago to an open spruce forest 20,000 years ago.

At one of the sites they felled a living honey locust tree and they noted the thorns were robust up to about 18 feet, as far as a ground sloth or mastodon could reach. Higher than that, the thorns were small or non-existent.

Here's the list of species from the Jones Spring site which dates to > than 40,000 years BP.

There were plant macrofossils of juniper, maple, dowood, plum, cherry, hazelnut, hawthorn, hornbean, oak, honey locust, ash, hickory, and osage orange. The pollen was 30% pine, 10% oak, with high percentages of sedges, grass, and ragweed, indicating lots of meadows as well as forest.

Animal fossils included box turtles, painted turtles, alligators, ducks, Harlan's ground sloth, gophers, giant beavers, voles, raccoon, saber-tooths, mastodons, mammoths, horse, tapir, camel, white-tail deer, long-horned bison, and woodland musk-ox.

Here's the list of species from the Trollinger Spring I site.

Painted turtle, black bear, mammoth, horse, deer, bison.

From Trollinger Spring II.

shrew, field mice, bog lemming, mastodon, stilt-legged deer, and woodland musk-ox.

The Boney Spring site was interpeted to be from a full glacial about 18,000 calender years ago. Here's a partial list--I'm skipping the abundant reptile and mollusk fossils. Note: no alligator present here!

Spruce, larch, moss, boreal beetles, Harlan's ground sloth, shrews and moles, cottontails, fox squirrels, marmots, chipmunks, flying squirrels, gophers, giant beavers, field mice, wood rats, bog lemmings, voles, meadow jumping mice, raccoons, mastodons (at least of 31 individuals) horse, tapir, and white-tail deer (cf).

Source: "Insularity and Mastodont Extinction," by James King and Jeffrey Saunders in Quaternary Extinctions edited by Paul Martin and Richard Klein.

[Auspex]

^^

No birds...see what I'm up against?

[Guest Smilodon]

A while back I put some info on hedgeapples in another thread, which generated some interest, so here is another iceage survivor, the honey locust. The honey locust, Gleditsia triacanthos is an early invasive species here in Missouri, and actually makes a very nice tree- except for the thorns. These thorns appear to have no apparent function, so why are they there? They are probably an adaptive response to the large pleistocene animals, particularly mastodons, who may have tried to push the tree over to get at the sweet fruit pods as they ripen. Trees with thorns didn't get pushed over by elephants, so they lived longer, so they produced more offspring, which tend to look like their parents.

The tree is also interesting in that it is a legume, a group of plants that symbiotically live with nitrogen fixing bacteria, giving them an advantage in poor soil locality where nitrogen is the limiting nutrient. Other legumes include beans, peas, and clover. Other trees would include the Red Bud.

Trees are not a natural group, meaning that trees are not necessarily closely related. Many plants have experimented with gigantism, which we think of as trees, but they are not necessarily closely related. The Fern Trees come immediatly to mind, but other plants also have trees. Monocots, which are the group that contains the grasses have experimented with trees, the most commonly thought of is the palm, but grass has also grown its tree-like member, which we call bamboo.

School starts Thursday, just trying to get back into the swing of things.

Brent Ashcraft

Is this strategy similar to Acacia and cactus?

[ashcraft]

Is this strategy similar to Acacia and cactus?

I believe somewhat similar, except the honeylocust is to protect the trunk from being pushed over, while cactus is to protect the stem from being eaten. Cacti spines are modified leaves, while the locust spines are modified stems.

Acacia are a fascinating group, some are thorned for protection, while others have modifications that allow ants to live in hollows in the tree, and even receive food from the tree to keep them living there, the ants then attack any insects, or even larger, that land on the tree.

Brent Ashcraft

[ashcraft]

I corresponded with Dr. Saunders of the Illinois State Museum about a paper he wrote in the early 1990's. He was with a group of scientists who studied several Pleistocene fossil sites in southern Missouri which are now flooded by Truman Lake. Apparently, during the Pleistocene there were artesian springs in the region that attracted mastodons. There were lots of plant macrofossils that showed the change in the environment from a broad-leafed forest, 50,000 years ago to an open jack pine parkland forest 30,000 years ago to an open spruce forest 20,000 years ago.

At one of the sites they felled a living honey locust tree and they noted the thorns were robust up to about 18 feet, as far as a ground sloth or mastodon could reach. Higher than that, the thorns were small or non-existent.

Here's the list of species from the Jones Spring site which dates to > than 40,000 years BP.

There were plant macrofossils of juniper, maple, dowood, plum, cherry, hazelnut, hawthorn, hornbean, oak, honey locust, ash, hickory, and osage orange. The pollen was 30% pine, 10% oak, with high percentages of sedges, grass, and ragweed, indicating lots of meadows as well as forest.

Animal fossils included box turtles, painted turtles, alligators, ducks, Harlan's ground sloth, gophers, giant beavers, voles, raccoon, saber-tooths, mastodons, mammoths, horse, tapir, camel, white-tail deer, long-horned bison, and woodland musk-ox.

Here's the list of species from the Trollinger Spring I site.

Painted turtle, black bear, mammoth, horse, deer, bison.

From Trollinger Spring II.

shrew, field mice, bog lemming, mastodon, stilt-legged deer, and woodland musk-ox.

The Boney Spring site was interpeted to be from a full glacial about 18,000 calender years ago. Here's a partial list--I'm skipping the abundant reptile and mollusk fossils. Note: no alligator present here!

Spruce, larch, moss, boreal beetles, Harlan's ground sloth, shrews and moles, cottontails, fox squirrels, marmots, chipmunks, flying squirrels, gophers, giant beavers, field mice, wood rats, bog lemmings, voles, meadow jumping mice, raccoons, mastodons (at least of 31 individuals) horse, tapir, and white-tail deer (cf).

Source: "Insularity and Mastodont Extinction," by James King and Jeffrey Saunders in Quaternary Extinctions edited by Paul Martin and Richard Klein.

Thanks, that looks like a paper that I need. Mr. King also wrote a paper on the Holocene drying, where he sampled peat out of a bog deposit near here.

On a side note, Truman lake isn't in the southern part of the state, it is central, but really just nitpicking.

Brent Ashcraft