Carya illinoinensis (Pecan)
- Images, plant synonyms, distribution map, and scientific classification. Includes conservation status.
- http://plants.usda.gov/java/profile?symbol=CAIL2

Carya illinoensis (Pecan)
- Native range, climate, associated forest cover, and detailed facts on reproduction and growth. Discusses human and wildlife uses.
- http://www.na.fs.fed.us/spfo/pubs/silvics_manual/volume_2/carya/illinoesis.htm

Pecan Breeding and Genetics
- Includes information and images of many cultivars, as well as species accounts for pecans and all other U.S. hickories.
- http://aggie-horticulture.tamu.edu/carya/

Carya illinoinensis
- Species account from the USDA Forest Service (misspelled as C. illinoensis on this site).
- http://www.fs.fed.us/database/feis/plants/tree/carill/