Jepson (2012) (APG System)



Jepson (1993) (Cronquist System)



In California, Betulaceae is represented by three genera: Alnus (Alder), Betula (Birch) and Corylus (Hazelnut). All members of Betulaceae, and indeed all members of Fagales, are woody plants. All members of Betulaceae, at least in California, are trees.

Plants in Betulaceae favor moist to wet soil. Alnus (Alder) and Betula (Birch) are characteristic of lower flood plains. Birch is found only in northern California in areas with higher rainfall. Corylus (Hazelnut) has a wider range than the others, and is normally found on hillsides, however, it requires deep forest soil with available summer moisture. It grows in the full sun where it is cool and foggy. In hotter areas, hazelnut only grows in the shade of other trees.

Plant Relationships

Native Genera:



Other Common Genera:



Related Families:


(Beech, oak, chestnut)


Growth Forms:

All members of Betulaceae are trees.


Alternate branching.


Simple leaves with dentate margins.


The flowers are catkins at the tips of branches.


Alder and birch produce seed in what appear to be miniature pine cones at the tips of the branches. They are often in clusters of 3 or more.
Corylus produce the commonly known hazelnuts. These look like small acorns in a papery husk.

Growing Conditions

Sun and Exposure:

These plants are shade tolerant, and often grow under a forest canopy. It local conditions are cool or foggy, they grow better in full sun.

Soil and Moisture Requirements:

All members of Betulaceae require deep soil with available moisture, especially in late summer. Alder and birch are restricted to moist sites; hazelnut is somewhat more flexible.

Horticulture and Restoration

Horticultural Comments:

In California, it is difficult to use alder and birch in landscapes, unless you can provide them a consistent irrigation source. Alder can be highly reliable, however, in the proper natural setting.
Hazelnut is a sturdy, reliable landscape plant that would be used as a large shrub or small tree.

Wildlife Habitat:

Hazelnut provides fruit in August and early September.

Restoration Projects:

Alder is widely used in riparian restoration projects, especially within the floodplain. In the right conditions, it establishes easily and grows fairly rapidly.
Hazelnut is not used very often, primarily because it is not found in the habitat types where most restoration occurs. It would otherwise be a very popular plant because it establishes readily and produces wildlife forage.

California Native
Plant Guide


Dicot Plant Families

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