Jerusalem Thorn, 5/23/10
In Full, Glorious Bloom...I have been stalking this amazing Jerusalem Thorn tree for the last four or five years each spring when it blooms.
It grows near a railroad trestle, at the end of an obscure dirt and gravel road off Oak Lawn across from the Infomart. You'd almost never know it was there, unless you were looking for it.
Actually, designer Emily Summers spotted it first. A group of us were in the car together one misty spring morning as a part of a small informational tour on the development of the Trinity River. While the rest of us were looking at who knows what, Emily spotted this tree as we were leaving. "What a glorious specimen," she said, gazing out the car window at its weeping bouquets of yellow blooms. We all paused for a moment to study it; no one knew what it was.
After I got home, I looked it up online. Here's what I found out:
Jerusalem Thorn, or Parkinsonia aculeata, are native to Mexico and the more arid parts of the southwest. They thrive in drought conditions and sandy, well drained soil. They are often found near ravines that flood, when their seeds are washed away by the rushing water and implanted in the dirt after the water recedes.
Graceful, whip-like branch tips allow the tree to sway in strong winds. Branches also have long, thick thorns. 
In areas where Jerusalem Thorn trees are not native, such as in Florida, they are treated with the same disdain as the kudzu vine, both of which tend to go all crazy and take over. In Florida they hate the trees so much it's illegal to buy or sell their seeds. I've read that they are not welcome near pastures in Texas either, where they tend to grow in massive tangles along creeks and rivers, their thorns preventing livestock from drinking.
They were once more common in Dallas, and now they're pretty rare. This one has probably survived so long because it's in a spot that hasn't been developed, and probably won't be, unless they redirect the train tracks elsewhere. 
This one, because of its remote location (you can see the dirt road and the Infomart behind it) has thrived for a couple of decades, no doubt. They live for only 15-20 years, and I read that mature ones are wider than they are tall, with branches bowing towards the ground. This one must be middle aged.
Bonus: Here's a close up of a black cat sitting peacefully under the tree as I took pictures at sunset one evening last week. I got the feeling this was his spot, the way he's perched on the rock. He never moved the whole time I was there, shooting. I don't blame him. Spring is brief. The blooms probably attract all kinds of butterflies and birds, and he likes to be ready.
