You might want to consider one of the Ribes or flowering currants. Ribes sanguineum is a west coast native that blooms in very early spring with long pendant racemes of pink or white flowers. An early hummingbird attractor! Ribes odoratum or clove currant is native to large portions of the midwest and blooms in April with yellow, spicy scented flowers and will often have some nice fall color. Both are happy in part shade and pretty drought tolerant once established.

One of my favorite understory trees is serviceberry (Amelanchier). There are a number of different species with different ranges and growth forms -- some are shrubbier, others tend to be small trees (often multi-trunked). They have beautiful white flowers early in the spring, and edible (by humans and wildlife) blue berries in mid summer -- they're sometimes called Juneberries. The fall color can also be good, ranging from yellow to orange to red.

Good luck. Maples are tough competitors -- for both moisture and light.

Witch hazel? Not sure about its water needs,though.

Thanks for your suggestions. I have considered a witch hazel, hamamelis x intermedia "Diana," to be exact. Other options include Harry Lauder's Walking Stick or cornus kousa "Snowboy." Which variety of serviceberry tolerates quite a bit of shade?

Gardengal48, do you know if Ribes is prohibited in Michigan? This is noted in "Dry-Land Gardening," a book on Xeriscaping. If not, it sounds like an excellent choice.

The two Amelanchier species that are most widely distributed in the northeast are A. arborea (downy serviceberry) and A. laevis (Allegheny serviceberry). Both will perform better (better fruits and fall color; faster growth) in full sun, but around here A. arborea commonly occurs in the understory.

Arborea is one of the many species that prefers the elusive 'moist, but well-drained' soil. I have two young arbora in a mostly shady site on a slight slope with heavy soil -- but they are growing pretty slowly.