Native Plants A-Z
Cephalanthus occidentalis (sef-uh-lán-thus ok-si-den-tá-lis), or Buttonbush, is a deciduous wetland shrub that anchors riparian food webs and is easily recognized by its spherical white flower clusters.
Native to lowland wet areas, Buttonbush can be found locally in suitable moist habitats of the San Lorenzo Valley, particularly along slow-moving creeks, seasonal ponds, or shaded floodplains where water pools in winter and spring.
Its dense, globe-shaped clusters of white tubular flowers bloom from late spring into early fall, offering rich nectar that attracts a wide array of native pollinators. During midsummer dormancy in other plants, Buttonbush provides one of the most productive nectar sources, drawing bees, butterflies, hummingbirds, and beetles in abundance. In turn, these insect visitors become vital food for nesting birds and amphibians, tying Buttonbush into the broader seasonal food web.
Beyond pollinators, Buttonbush supports birds and amphibians, offering seeds to goldfinches, sparrows, and waterfowl, while its dense structure shelters frogs, salamanders, and nesting songbirds. It is also a larval host plant for the Buttonbush Sphinx moth (Sphinx eremitus), part of the native lepidopteran community that supports insectivorous birds like Pacific-slope Flycatchers and Black Phoebes, species common to the SLV’s riparian corridors. Together, these relationships position Buttonbush as a structural and trophic keystone in riparian habitats.
As a restoration species, Buttonbush excels in moisture-retaining soils along bioswales, pond margins, and slow-draining slopes. Its fibrous roots help stabilize saturated banks, reducing erosion and supporting microbial and mycorrhizal communities below ground. The shrub tolerates seasonal inundation and thrives in areas where other woody plants may struggle to survive. Once established, it is remarkably resilient, requiring no summer water and showing moderate deer resistance due to its bitter foliage.
Its vertical structure and seasonal appeal make it especially valuable in riparian restoration plantings. In gardens, Buttonbush offers more than ecological value; it adds sculptural form and seasonal fragrance. With proper siting, it becomes a dynamic centerpiece in rain gardens, wildlife hedgerows, or amphibian-friendly zones.
Buttonbush
Cephalanthus occidentalis
sef-uh-lán-thus ok-si-den-tá-lis
KEY DETAILS
Plant Type
- Perennial deciduous shrub
- Locally native to moist lowlands and riparian corridors of the Santa Cruz Mountains
Light
- Full sun to part shade
- Blooms best in full sun but tolerates dappled woodland light
Soil
- Prefers moist to wet, humus-rich soil
- Thrives at edges of bioswales, ponds, creeks, and seeps; tolerates flooding and poor drainage but not dry or compacted soil
Size
- Typically 6–12 ft tall and 4–6 ft wide with a multi-stemmed growth form
- Readily pruned to maintain smaller form or more compact habit
Bloom Time
- Late spring to early fall (May–September)
- Distinctive white pompom-like flower clusters are rich in nectar and highly attractive to pollinators
- Rust-colored seed balls persist through fall and winter, feeding birds and adding ornamental interest
Sun Exposures per day
Shade: Less than 3 hours of direct sun
Part shade: 3-4 hours of direct sun
Part Sun: 5–6 hours of direct sun
Full Sun: Receives 6+ hours of direct sun