First, that weird name, Lead Plant. Says the Missouri Botanic Garden, the plant was once thought an indicator of lead in the soil. Meaning what? Lead to mine? Or lead contamination, land to avoid? Doesn't say, dunno. As usual, Latin is better. Amorpha canescens. Amorpha means mis-shaped, in that the flowers are missing most of the petals their other pea-family relatives have. Just one here, thank you. Canescens means grey or hairy, which the delicate ferny foliage certainly is.
The plant is as tough it is adaptable, native from the Canadian sub-Arctic to the Gulf Coast. At home, it's a small-scale early-Summer thrill to puzzle experts as well as just-folks gardeners.
The profuse spikes of indigo-blue flowers are way too early to be caryopteris, which is the same size bush (a foot or two high and two or three feet wide) but doesn't bloom until August. But caryopteris foliage is simpler and a bit bigger anyway. As are the leaves of buddleia, the other possible floral look-alike. But it too is in bloom much later in the season, not by the end of June, and even in the dwarf forms is distinctly bigger and more erect.
All Lead Plant wants is these three things:
1. Lots of sun.
2. Good drainage in the Winter. 3. Freedom from herbivores, deer included: The foliage tastes great (to them) and is nutritious too. No idea of its lead content though. And all you need to do for your Lead Plant is to cut it to the ground without mercy in early Spring: As with caryopteris and buddleia, the flowers happen at the tips of new growth, so last year's isn't worth a damn.