First, the welcome visitor: a tiger swallowtail (Papilio glaucus) that enjoyed the dianthus on the patio yesterday:

Now the intruder

It all started with the Idaho locust tree. I love purple flowers, and when I saw purple robe locusts (Robinia ambigua) around town I had to have one in my yard. (The Idaho locust, which I ended up buying, blooms a couple of weeks later than the purple robe.) It took a long time for it to get established in our salty clay, but this year it's really putting on a show.


One of the things that made me think it would be good for our yard was it was supposed to grow fast and tolerate heat and poor soil. (To give you a clue about our soil, the tree is surrounded by salt grass.)

I should have paid more attention to the rest of the description in the Sunset guide: "Drawbacks: wood is brittle, roots aggressive, plants often spread by suckers."

A few years ago, another locust tree popped up nearby. Cool! I thought. A free tree! It grew amazingly fast, much faster than the original tree, in fact. When it bloomed, it had white flowers.

While I wasn't paying attention, locust suckers started popping up all around it. I didn't realize it at first, but each sucker was coming up from a root. And the suckers were coming up further and further from the tree . . . Here's an example:


I let them get out of control until I had a forest of locust suckers. I'm serious. Last year I cut them all down, and this year Phil cut down the main sucker tree. Since then he's been trying to hack out the roots. Here are just a few to show you how big and long the roots are (these are more than 10 feet long).



Unfortunately these continue under the lawn, but it would destroy the lawn to tear them out. (Well, the moles have nearly destroyed the lawn already, but that's another story.) At this point, we're not sure what it's going to take to completely solve the problem. I'm not ready yet to get rid of the original tree. I know now we need to be ruthless with the suckers.