A vine such as clematis or morning glory. A tall, skinny tree such as Lombardy poplar. Skyrocket juniper and dwarf Alberta spruce also suit narrow spaces. The spikelike foliage and jewel-colored spring flowers make them especially beautiful beside water. Summersweet, Clethra alnifolia, which is native to swamps and other wet spots, grows about 5 feet tall.
Fragrant flowers are white or pink.
You can eliminate the problem and expand your plant choices by building a raised bed. Other spots, usually streamside, are constantly wet and require plants, such as summersweet or water irises, that are at home there. And you'd like this done in your lifetime. Burford hollies grow tall and reasonably fast, yet tend to be space-grabbers. Camellias are also old favorites.