^ Dunno, I have no personal experience with DED? As I think it hasn't become "epidemic" in TX yet: "Very little research has been conducted regarding Dutch elm disease in Texas and little is known about how the disease will progress through the state. Early observations indicate that the disease is not slowing down, and is causing damage on both public and private land." "Dutch elm disease, a fungus related to oak wilt, which destroyed as many as 40 million elms. The fungus, which came to the United States from Europe arrived here in 1930 and was confirmed in Texas in 1970." BTW, I wonder if #2 could also possibly be a Slippery Elm (Ulmus rubra)? The 2 are very similar, except the Slipper Elm's leaves are almost the same as American Elm, but are much scratchier due to high silica content in the leaf.

Found another one of these elsewhere in the same park: Yea, I'm also wondering if this might be Eve's Necklace (Styphnolobium affine), now? Does it usually start out as very spindly, green-skinned saplings like this one, too?

^ Yes, thanks! Definitely a Hercules' Club (Zanthoxylum clava-herculis)! Man, I am so psyched! First time ever I've discovered this unique, native member of the Rutaceae (Citrus family) and the same Zanthoxylum genus as Sichuan Pepper! No wonder it had a strong, aromatic smell when I crushed a leaf... But I will now definitely have to actually taste test a leaf next!

This plant about ~4' tall was found growing in a wooded part in a park. It had opposite, pinnate, diamond-shaped leaves a little over an inch long. What is it?