Corydalis solida is a spring blooming (April/May) ephemeral. After flowering the foliage begins to deteriorate and is usually gone (or removed) by midsummer. But sometimes climate or other cultural conditions can encourage an out of season flowering. Prefers at least partial shade and consisently moist but not wet soils

Yellow flowering fumewort, Corydalis lutea, is not ephemeral and can have a very extended (May through September) bloom season.

Very early for me (March/April if I recall correctly) and disappears entirely soon after flowering. Mine are under a weeping birch along with Hellebores, ferns, Cyclamen hederifolium etc.

If your reappearing Corydalis was yellow it wasn't C solida.

Quite spring ephemeral.

It's nothing like the prolifically seeding and spreading Corydalis lutea which is currently still blooming in the garden here. The only draw back for me has been that once you've planted it, you've got it forever. With its flashy root, it's extremely easy to pull out/rake away C. lutea, but it's close to impossible to remove the corns that C. solida grows from.

Still with the space and location for it, see below (Merlin's Hollow, May 10, 2014).

Ah! Thank you. I had forgotten that not all Corydalis is "Solida." I was just writing from the package. Now that you remind me, "Corydalis lutea" was what the person who gave me the yellow one called it.

This explains a lot. The Corydalis lutea is perfectly fine staying where it is. Corydalis "Solida" will be going where I need something ephemeral.