The Chinese Witch Hazel (H. mollis) is also at full bloom right now. It can be identified by its more linear golden yellow petals. It also has a tendency to hold onto its old leaves, as shown here.
The other ‘native’ is the Common Witch Hazel (H. virginiana). This species is widely distributed in the Eastern US and is normally found in upland woodlands. The bright yellow flowers of this plant open up in the fall, while the leaves are still attached, so it is easy to miss them.
One place to see these plants in the Boston area is at Mount Auburn Cemetery. You can also see more Mount Auburn photos at the Friends of Mount Auburn Flicker page.
While the origins of plant names can be rather fuzzy, one that stuck in my mind for witch hazel is that it often gets ‘warts’ on its leaves due to a gall formed by the spiny Witch-Hazel gall aphid. The red-tinged galls have long spines that look something like a hairy wart. In most cases these galls do not do serious harm to the plant.