The River birch is a large, fast growing, deciduous tree capable of reaching 80 feet but more likely 35-60'. Often grown as a multi-stemmed tree to show of the bark. It forms a pyramidal shape and can be 30' wide. Give it room. Very interesting bark when mature. Fall color is not as great as other birches but not bad.
These are going fast, most of the cul-de-sac on Mar Vista (in Aptos) was stripped of trees this winter.
Leaves are alternate, simple, rhomboid to ovate shaped, margins doubly serrated, base is wedge shaped. Dark green above and glaucous (waxy layer) below. Leaves generally 1- 1/2" 3- 1/2" long. Petiole is slightly hairy.
Stems are light reddish brown and slightly pubescent when young. Much smoother than the other birches and has a smaller bud.
Flowers are monoecious (male and female flowers on the same plant). Males in overwintering catkins 2-3" long. Females emerge with the leaves, small (3/4") red and erect. This image shows the males and the pollenated females.
Fruit are small nuts in a catkin. All the birch fruit look alike to me. You can see a picture of the nuts in the post on Betula pendula.
The bark of the species is usually dark brown with stiffly exfoliating sheets. Quite rough in appearance. There will be a few that show some smooth pinkish white peeling bark.
The cultivar 'Cully' is such a selection beautiful bark, larger leaves and faster growth. 'Cully' has the common name of Heritage Birch. This birch selection has very nice bark, and is very fast growing, with slightly larger leaves. I am not sure I have seen any around here but I will keep looking.
Misidentification: Other birches perhaps, but not with that bark. Look at the stems, once you know its a birch it will be easy.
Not really common,
Aptos:
Mar Vista Dr. across from the intersection of Madeline along the street and into the small cul-de-sac but you better hurry, many of them were removed this winter.
There are some young ones on the Cabrillo campus
1770 Dolphin Dr are a few nice ones
Soquel:
Soquel along Soquel/San Jose at the entrance to the blue ball park.
Santa Cruz:
619-623 Seabright Ave - Condo driveway