Trees of Big Sur and the Santa Lucia Mountains of Central California

Red Alder Alnus rubra

A member of the Birch Family the Red Alder is a deciduous medium sized tree 50-100 ft. tall (even taller in the north). It is found in riparian habitats, steambanks, and wet moist places. It is often growing in association with Willow, Sycamore, Black Cottonwood, Redwoods, and Big-leaf Maples. The female catkins look like small conifer cones. In the Santa Lucias it occurs from near sea level to near 500 feet.

Note: Red Alder is closely related to White Alder and the two species are difficult to differentiate in the field when growing together. Characteristics of the leaf can be used to distinguish these alders, but is difficult to separate the species in winter months in the areas where they overlap. Red Alder is less common in the Santa Lucia range.

Red Alder in the Santa Lucia Mountains
80 foot Red Alder trees growing on a stream bank.

Red Alder with female catkins
On Red Alder leaves the major veins are indented. Note the erect green female (pistillate) catkins or cones.

Red Alder Leaves
Red Alder leaves and cones.

Red Alder Catkins male staminate
The dropping male (staminate) catkins of the Red Alder.

Red Alder Leaf margin revolute
The Red Alder has a distinct leaf margin that is tight rolled under or revolute on the leaf edges. Mature leaves will often have a 'hairy' rusty underside.

Red Alder leaf edge
Close-up of the revolute or tightly curled leaf margin that is the distinguishing field characteristic of the Red Alder.

In the Santa Lucias, White Alder are most common. If you are over 500 feet in elevation assume it is a White Alder. In mixed growth areas near the coast and below 500 feet refer to leaf characteristics. Also see: White Alder

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