 of plants tend to appear together wherever the climate, soil and temperature are suitable for them. These familiar groupings create distinctive habitats, each nourishing its own ecosystem of plants, insects and animals. In addition to evergreen forests, some of the predominant habitats in Marin include riparian, oak woodlands, chaparral and grasslands.
The riparian community that flourishes wherever there are waterways is populated by plants that not only require somewhat regular water, but can survive inundation — some for as much as two months at a time. This habitat is rich with places of refuge and diverse resources for a multitude of visitors, many of which are temporary migrants. Here, willows, rushes and horsetails help anchor the streambed, while ferns, thimbleberry and sedges stabilize the banks and create tangles of vegetation.
A little farther from the stream banks, deciduous valley oaks and buckeyes and evergreen redwoods, bays and madrones help cool the waters in summer and allow more light in winter, both conditions vital to the creek’s life support systems. Natural sloping banks, fallen logs, and dense overhanging vegetation create dappled shade and resting places for salmon and steelhead. A walk along Devil’s Gulch to Stairstep Falls or from Cataract Creek to Cataract Falls will cross waterways where giant elk clover and huge chain ferns dominate the banks, creating the atmosphere of ancient forests. Mount Tam’s Rock Spring Trail leads to a meadow traversed by a stream along which fragrant native azaleas bloom in late spring. Thanks to the mountain, the county is crisscrossed with streams and riparian habitats, yours for the exploring.
Most plant communities in Marin contain various species of native oaks, but an open-canopy oak woodland is a very distinctive plant habitat, rich with biodiversity and supporting more species than any other habitat type in the state. Oak woodlands primarily become established at lower elevations and in soils too dry to support a forest. Meadow grasses and wildflowers thrive along with oaks in more open sites. The show begins early in January with fragrant white milkmaids, followed soon by the golden glow of buttercups, until the blues of hound’s tongue and ground iris become predominant. Autumn brings a show of golds and reds as leaves turn color, coffeeberry and toyon bushes hang heavy with fruit, and clouds of creamy cotton-like flower puffs cover the stands of coyote brush.
An oak woodland is alive with life in all seasons. Mule deer browse the understory plants but depend on the acorn harvest for a major component of their fall diet. Acorn woodpeckers create stores of the oak nuts in communal granary trees and excavate nesting cavities that will be repurposed by other residents. As many as four thousand species of insects are associated with oaks, including the California Sister and Mournful Duskywing butterflies. Native bees collect oak pollen, and Anna’s hummingbirds forage for small insects among the growing tips. The best examples of true oak woodlands occur in Novato, with exceptionally beautiful walks along the Bahia Ridge Trail at Rush Creek Open Space Preserve. Here, deciduous blue oaks predominate but mingle with coast live oaks and magnificent large old specimens of common manzanitas with deep red bark and gnarled limbs.
At the sunnier edges of the woodland, California sagebrush, sticky monkeyflower and California bee plant may be seen growing together. This same trio is also at home in the chaparral, a plant community prevalent throughout Marin, mostly on south-facing slopes with thin, rocky soils. Chaparral shrubs have evolved to thrive in the resulting nutrient-poor soil where other types of vegetation struggle. Many of the plants are evergreen and have thick, leathery or resinous leaves that enable them to survive the summer drought. Marin’s chaparral habitats are in good shape due to their dense growth on thin soils, two factors that make it hard for nonnative species to get a foothold.
From the chaparral community, we get two of Marin’s most iconic plan