Fagus sylvatica purpurea
There are two small beeches in the park, one a copper beech. See Wikipedia entry here for the genus.
Beech, either American or European, in the southeast triangle in July, looking southwest
Young copper beech in the west triangle in July with its distinctive purple leaves.
The beech holds on to its dead leaves late into winter. Before the leaves turn brown in the fall, the anthocyanin that turns the leaves purple may be broken down leaving the leaves as green as the wild-type beech.
Young copper beech in the west triangle on April 22.
There are two bowl-shaped female flowers at the top of the photo. The male flowers hang on long peduncles and have multiple filaments with black anthers.
Copper beeches are alleged to come from a single purple-leafed beech tree discovered 400 years ago. Copper beeches grown from seed may have variable intensity of the purple color. Many are therefore grafts of purple-leafed beeches onto European beech root stock. The different trunk structure at the base of our copper beech indicates that it was a graft. Graft scars are even more clearly seen on the hawthorn trees planted on the sidewalk on 19th Street.
Botany 101 Bonus
The maple trees in the Park withdraw all the green chlorophyll from their leaves, leaving the anthocyanins and other pigments in the beautifully colored leaves as those leaves separate from the tree and fall to the ground. Other trees are more stingy, and withdraw all the pigments from the leaves, so that dull brown leaves fall to the ground. Still others, like our copper beech and oak, hold on to those dead brown leaves over the winter.
Marcescence is the scientific term for the retention of dead plant organs, usually leaves, that normally are shed. This occurs especially in the young trees, and you will notice that there are more dead leaves on our young beech than on our mature red oak, and more near the bottom of the tree than at the top. Why is this trait seen in the beech and the oak? They are related; they both belong to the same taxonomic family, and no other tree in the Park is in this family.
It is not clear of what advantage is marcescence to the survival of the tree. Theories are that it may discourage herbivores like deer or that it is allows the leaves to fall and act as fertilizer in the spring when the new trees are breaking seed. It is almost like a compromise between being an evergreen with leaf retention through the winter and being deciduous with leaf fall in autumn.