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Wednesday, May 15, 2013

Acer macrophyllum - Bigleaf Maple

The bigleaf maple is a common riparian tree seen in most stream beds in the county. It is native range is most of the pacific coast from just south of Santa Cruz up to British Columbia. In Maple Valley Washington they have a big leaf contest, and some of the leaves are really huge, like up to 24" across.

This is a medium to large deciduous tree, 30-100 (but generally about 50 around here) feet tall and about half as wide as tall, forming an upright oval shape. Generally multiple trunks. Very fast growing. Fall color can be yellow in areas getting frost. I have found it difficult to find one planted in a residential area, so the picture below shows it in it natural area taken from the foot bridge of Soquel Creek.

My new favorite Bigleaf maple, in Portland, formerly pollarded and eventually left to grow.

Leaves are deciduous, opposite, simple, palmately lobed with 3 or 5 lobes. Leaves are variable in size, maybe 5-18" long and almost as wide. They will not get that large here, its too dry. Dark green above and slightly pubescent,  pale green below. Lobes are very deep each with several teeth but more or less entire otherwise. Very long petioles, 4-6" long. In spring the foliage can be various shades of purple when emerging from the buds. White milky sap from the petiole or stem.

This is a common leaf shape in our area.

Its somewhat interesting to note that some of the plants have leaves that emerge purple and then fade to green. This is also seen in A. platanoides and resulted in a cultivar named 'Schwedleri'. Eventually someone found a purple one that lasted all summer. I am surprised that has not happened with this species. Okay, so it has, there is a cultivar called 'Mocha Rose' introduced from non other that Bucholtz and Bucholtz Nursery (one of my all time favorites) . Here is a great link to a blog post on this cultivar and species by Talon B himself Article on species and cultivars. You should look at his photographs, wow.

(There is also a cultivar called Seattle Sentinel' that is columnar and might be worth having around here.)

Flowers (seen above) are quite showy in the early spring. Staminate (male) and perfect flowers in drooping clusters, up to 10" long. Flowers are slightly fragrant, 1/4" diameter and yellow. 

Fruit is typical of maples, with the samaras arranged in pairs. Samaras about 2" long, wings at about 90 degrees or less. Samaras arranged in long drooping clustes up to 10" long. Light tan colored and covered with yellow or brown hairs except on the wings which are glabrous.

Stout twigs, green to reddish colored, large buds with hair on the margins. Notice the white sap coming out of the stem by the bud, one of several maples that have this.

Trunks lightly checked, mostly silver gray for many years.

Fall color is a nice yellow. This is up in the rainy PNW.

You might think its a London Plane but the LP has alternate leaves, or you might think its a Silver Maple, Acer saccharium. The silver maple gets its name from the silver undersides of the leaves so look for that, as well as the leaves. The silver maple leaves are smaller, the lobes are more deeply incised and have more minor teeth on them than our native.

Silver on the left - Big leaf on the right

Any riparian area. Along Hecker Pass going over to Gilroy.
Highway 1 and 41st ave in the clover leaf by Home Depot and the opposite side.

Along Park Drive nearing the beach, on the railroad side of the street.

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