In the article from the Arnold Arboretum there is an incredible photo of the root system. It is an amazing underground structure. It is now believed that the root system is a scaffolding support system to hold the trees erect in the swampy conditions...buttressing the base of the tree. My favorite reference, National Forestry Service Silvics manual, has both answers for the knees. Trees are such interesting structures.
When learning the difference between the Baldcypress and Dawn Redwood I had two different people give me their methods of knowing which is which. Taxodium distichum vs Metasequoia glyptostroboides. One said Taxodium DISTichum ---leaves arranged like discs, one on top of the other, alternating along the stem or METAsequoia...the leaves meet--arranged opposite. The other person said the Metasequoia is MEATIER...thicker leaves. Right Les?
The bark is reddish brown and as the tree ages it becomes shredded and coarse...it can peel off in strips. The young tree is pyramidal in shape, but as the tree matures, the top flattens out. The trunk flares out at the base, often quite enlarged.
The leaves are soft to the touch and drop in the late fall. In the spring the new leaves emerge for the new season.
It is a monoecious tree, its fruits mature in one growing season. The female fruits are rounded cones, either in clusters of two, three or alone.