Alnus maritima (Seaside Alder)
- Images, plant synonyms, range map, scientific classification, and wetland indicator status.
- http://plants.usda.gov/java/profile?symbol=ALMA7

Alnus crispa (Green Alder)
- Describes physical characteristics and habitat. Provides photo of branch with fruit and flowers.
- http://www.borealforest.org/shrubs/shrub2.htm

Alnus nepalensis
- Photograph of flowering parts.
- http://www.botany.hawaii.edu/faculty/carr/images/aln_nep_mid.jpg