Adenostoma fasciculatum (chamise or greasewood) is a flowering plant native to Oregon, Nevada, California, and northern Baja California. This shrub is one of the most widespread plants of the chaparral biome.
An evergreen shrub growing as high as 13 feet tall, Adenostoma fasciculatum sports dry-looking stick-like branches. The leaves are small, 4–10 mm long and 1mm broad with a pointed apex, and sprout in clusters from the branches. These clusters are known as fascicles, and give the species its Latin name. The leaves are shiny with flammable oils, especially in warmer weather. The branches terminate in bunches of white tubular flowers five mm in diameter, with five petals and long stamens. The fruit is a dry achene.
The oily leaves give rise to the common name greasewood.
There are two varieties which differ from each other in minor characters: A. f. var. fasciculatum, with leaves 5-10 mm, apex sharp; shoots hairless; and A. f. var. obtusifoliu, with leaves 4-6 mm, apex blunt; shoots slightly hairy.
Chamise is very drought tolerant and adaptable, with the ability to grow in nutrient-poor, barren soil and on dry, rocky outcrops. It can be found in serpentine soils, which are generally inhospitable to most plants, as well as in slate, sand, clay, and gravel soils. Chaparral habitats are known for their fierce periodical wildfires, and like other chaparral flora, chamise dries out, burns, and recovers quickly to thrive once again. It is a plant that controls erosion well, sprouting from ground level in low basal crowns that remain after fires, preventing the bare soil from being washed away.
Thickets of chamise are sometimes called chamissal. The species also gives its name to a specific chaparral (i.e., Adenostoma fasciculatum chaparral) dominated by A. fasciculatum.