Plant Communities of Mount Diablo State Park
Glenn Keator, Ph. D.
(Excerpted from MDIA's book Plants of the East Bay Parks)
Also called coastal scrub or coastal sage scrub, soft chaparral is dominated by small shrubs with "soft" leaves (leaves with a pliable, thin texture). Leaves may be heavily scented -- smelling of sage, turpentine, or mint -- to keep animals from browsing them. These fragrant oils also evaporate on hot days to cool leaves and inhibit growth of competing plants. All of these ploys prevent shrubs from losing precious leaves, since it costs energy and water to make new ones. Yet in summers with prolonged drought, soft chaparral shrubs may lose most of their leaves as a last-gap effort to keep from dehydrating faster than roots can replenish water from bone-dry soils. Winter rains bring temporary supplies of water during which leaves are replaced.
Soft chaparral is typical of rocky promontories in the fog belt, but components of this same community appear as temporary replacements for hard chaparral shrubs after brush fires.
Soft chaparral shrubs are varied, with some particularly aggressive pioneer species, such as coyote brush (Baccharis pilularis). Others include California sagebrush (Artemisia californica), with broad dark green leaves whose edges curl under; sticky monkeyflower (Diplancus aurantiacus), with sticky, viscid green lace-shaped leaves, again with curled-under edges; black sage (Salvia millifera), with highly aromatic dark green, narrowly triangular leaves; blue witch (Solanum umbelliferum), a green-twigged shrub whose fuzzy, light green leaves are cast away in summer; and poison oak (Toxicodendron diversilobum), with shiny, triparite leaves, which are lost early during severe drought.
Link to California Chaparral Field Institute website.