Platanus racemosa - Quercus agrifolia Woodland Alliance
California sycamore - coast live oak riparian woodlands

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation0-2400 m
  • State RarityS3
  • Global RarityG3
  • DistributionUSA: CA. Baja California, Mexico (TJM2)
  • Endemic to CaliforniaNo
  • Endemic to California Floristic Province and DesertsYes
  • Date Added1995/11/01

Characteristic Species

Platanus racemosa and/or Quercus agrifolia is dominant or co-dominant in the tree canopy in riparian habitats with Alnus rhombifolia, Juglans californica, Populus fremontii, Quercus lobata, Salix exigua, Salix gooddingii, Salix laevigata, Salix lasiolepis, Salix lutea, Schinus molle and Umbellularia californica.

Vegetation Layers

Trees < 35 m; canopy is open to intermittent. Shrub layer is open to intermittent. Herbaceous layer is sparse or grassy.

Membership Rules

  • Platanus racemosa > 30% relative cover in tree canopy; Quercus agrifolia, Salix species, or Populus fremontii may be co-dominant. (Evens and San 2005, Klein and Evens 2005, Keeler-Wolf and Evens 2006, Stillwater Sciences and URS 2007).
  • Platanus racemosa > 5% absolute cover in tree layer; in mixed stands, Populus fremontii < 5% absolute cover in the tree canopy (Potter 2005).
  • Platanus racemosa > 50% relative cover in the tree layer (Keeler-Wolf et al. 1997).
  • Quercus agrifolia > 50% relative cover in a riparian setting, or Platanus racemosa > 30 relative cover or sometimes > 15% relative cover as a characteristic tree with Acer macrophyllum, Acer negundo, Aesculus californica, Juglans hindsii, Quercus agrifolia, Quercus lobata, Salix laevigata, or Umbellularia californica (Sikes et al. 2023).
  • Quercus agrifolia > 50% relative cover in a riparian setting, often with Salix spp. and Toxicodendron diversilobum (Sikes et al. 2021, Buck-Diaz et al. 2021)


Gullies, intermittent streams, springs, seeps, stream banks, and terraces adjacent to floodplains that are subject to high-intensity flooding. Soils are rocky or cobbly alluvium with permanent moisture at depth. The USFWS Wetland Inventory (1996) recognizes Platanus racemosa as a FACW plant.

Other Habitat, Alliance and Community Groupings

MCV (1995) California sycamore series
NVCS (2009) Platanus racemosa temporarily flooded woodland alliance
Calveg California sycamore
Holland Central Coast cottonwood-sycamore riparian forest, Sycamore alluvial woodland, Southern sycamore-alder riparian woodland
Munz Not treated
WHR Valley foothill riparian
CDFW CA Code 61.310.00

National Vegetation Classification Hierarchy

Formation Class Mesomorphic Tree Vegetation (Forest and Woodland)
Formation Subclass Temperate Forest
Formation Temperate Flooded and Swamp Forest
Division Western North America Warm Temperate Flooded and Swamp Forest
Macro Group Southwestern North American Riparian, Flooded and Swamp Forest
Group Southwestern North American riparian evergreen and deciduous woodland