Alnus rubra
The upper stream banks are in the coast redwood ("Sequoia sempervirens") belt of the Santa Cruz Mountains while the lower stream banks are lined by red alder ("Alnus rubra"), big-leaf maple ("Acer macrophyllum"), California buckeye ("Aesculus californica"), Pacific madrone ("Arbutus menziesii"), California laurel ("Umbellularia californica"), and, in the lowermost portion, by willows ("Salix spp."). Occasionally encountered are tanoak ("Lithocarpus densiflora"), box elder ("Acer negundo subsp. californicum"), white alder ("Alnus rhombifolia"), black cottonwood ("Populus trichocarpa"), California nutmeg ("Torreya californica"), and coast Douglas fir ("Pseudotsuga menziesii var. menziesii").