Deer brush (Ceanothus integerrimus) is a woody shrub in the Rhamnaceae (Buckthorn) family native to the western United States, including Arizona, New Mexico, California, Oregon, and Washington. It grows in a wide range of habitats, from chaparral mountain shrub regions to hardwood forests and fir, spruce, and Ponderosa Pine communities, with the most abundance in California's chaparral. The species shows significant variability in form across its range. In some areas, it is a deciduous shrub 1-4 meters tall with an open, ascending to erect branching habit. In others, it is evergreen or semi-deciduous and decumbent. There are two recognized varieties, with overlapping ranges reflecting the species' adaptability.
Deer brush is a drought-adapted shrub that fixes nitrogen through root nodules formed by actinomycete bacteria. It produces fragrant flowers, typically white, though they may occasionally be shades of blue. While it can be tricky to grow in the garden, especially without providing the right conditions, it thrives best in mountain gardens and is particularly suited to growing in the shade of conifers or oaks. The shrub is browsed by wildlife, especially deer.