Deerbrush: Ceanothus integerrimus (Synonyms: Ceanothus andersonii, Ceanothus californicus) - Common around the southern base of Mt. Adams, but seen occasionally up to 3000' on the southeastern flanks.
Mahala Mat, Prostrate Ceanothus, Squawcarpet: Ceanothus prostratus (Synonyms: Ceanothus divergens ssp. occidentalis, Ceanothus prostratus var. laxus, Ceanothus prostratus ssp. prostratus) - Currently limited to within one-half mile of the western edge of the Klickitat Canyon.
Buck Brush, Redstem Ceanothus, Oregon Tea-tree: Ceanothus sanguineus - Currently only seen on the southeastern flank of Mt. Adams up to about 4100'.
Greasewood,Mountain Balm, Snow Brush, Sticky-laurel, Tobacco-brush: Ceanothus velutinus var. velutinus (Synonym: Synonym: Ceanothus velutinus ssp. velutinus) - Common on the eastern and southern slopes of Mt. Adams up to near the treeline.
Cascara, Chittam Bark: Rhamnus purshiana (Synonyms: Frangula purshiana, Frangula purshiana ssp. annonifolia, Frangula purshiana ssp. purshiana) - Currently only seen on open slopes on the south side of Mt. Adams, including Crofton Butte and the Aiken Lava Flow.