Aha!
There's a tree in my neighborhoodof I type I'd never seen before two years ago, when I noticed it blooming. It's smallish, about 30 feet tall, and has distinctive yellow flowers that hang in ice-cream-cone shapes. I have just managed to work out what it is: it's a laburnum. I am very pleased.
It occurs to me that I should go out back and check on my various irises, and if I want to get some columbine going indoors for transplanting, now's the time. I love perennials, they're so low-maintenance. Gonna try transplanting my grocery-store primroses outside too, as they are also perennials and I might be able to keep them going if I can make sure they're watered. They're hybrids--wild primroses are generally pale yellow--so they likely won't seed, but they'll stay alive for a few years if I can take care of them.