Red Maple

Acer rubrum

The Red Maple in the southwest corner of the west triangle blends in during the summer months, but turns scarlet in the fall. There is another red maple in the northwest triangle. It is the most abundant native tree in the eastern deciduous forests. See Wikipedia entry here.
It ranges from Newfoundland to Minnesota, and as far south as Miami and east Texas.
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Red maple in west triangle in July
Red Maple factoids:
  • The fruits of the red maple are those wind blown "helicopters," technically called samaras, seen in the spring.
  • Red maples are usually dioecious with separate male and female individuals, but can be monoecious, with both male and female flowers on one tree. Under certain conditions they can switch from male to female, male to hermaphroditic, or hermaphroditic to female.
  • The red maples that line 18th Street are all males. The two in the Park are females.
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This red maple in the northwest triangle, seen here in July, has female flowers in March. It will look red in spring from the flowers and samaras and in autumn from the foliage.
Red samaras on the red maple in the northwest triangle at the end of March. If it has samaras, it's a female.
Red maple in northwest triangle in November
Red maple descriptor tag from the Morris Arboretum
Botany 101 Bonus
News flash: Trees have sex lives. On flowering plants, the flowers are the reproductive organs of the plant. There can be flowers that are called perfect flowers, carrying both male and female organs, and these flowers are also called hermaphroditic. There can also be solely male or solely female flowers.
Some trees, like the common street tree ginkgo biloba, have separate male and female plants with male trees producing male reproductive organs and female trees producing female flower-like structures and seeds. These plants are called dioecious, which means two houses, and only the female plants bear seeds. Monoecious plants have both male and female flowers on one plant, like our contorted hazelnut in the eastern triangle.
Most trees, except for the conifers and technically the ginkgo, produce flowers. Most people when they think of flowering plants think of perfect flowers, or hermaphroditic flowers, with both male (pollen producing) and female (egg producing) parts on one flower. The red maple has a fluid reproductive strategy as noted. Other dioecious trees in the Park include the katsura, the fringe tree, and the honeylocust.
A diagram of perfect flower on the left, containing male (stamenate) parts and female (pistillate) parts, contrasted with the female only (pistillate) flower on the right. The anther produces the pollen grains which when introduced on the stigma elongate toward the ovule to fertilize it.
The flower buds on the red maple are some of the earliest to develop in the Park in the spring.
The tiny anthers that make pollen can be seen topping the slender filaments on the male flower. As of 2020, the red maple in the west triangle has perfect flowers and the maple in the northwest triangle has female flowers, both blooming in early March. The anthers on the male flowers are quite obvious, making it a little difficult to tell if a flower is perfect or only male. If that flower produces seed pods, you know it had female parts.
Trees that bloom very early are usually wind-pollinated, since so early in the growing season there are few insect pollinators active.
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There is another classification term for flowers that is sometimes confused with the perfect-imperfect dichotomy. A complete flower has all four parts of a flower: sepal, petal, stamen (male part), and pistil (female part), working from the outside to the center. An incomplete flower is missing one of these components. A complete flower is always perfect. An incomplete flower can still be perfect, if it is only missing sepals or petals. An imperfect flower is always incomplete.