According to the NPS website, "Riparian woodlands occur along canyon and valley bottoms with perennial or intermittent streams in nutrient rich soils, or within the drainage of steep slopes. Of all the plant communities in the Santa Monica Mountains, the riparian community contains the greatest species diversity. Also unlike other communities, riparian woodlands have multi-layered vegetation, with both an under and overstory. Dominant species may include arroyo willow (Salix lasiolepsis), California black walnut (Jugalns californica), sycamore (Platanus racemosa), Mexican elderberry (Sambucus mexicana), California bay laurel (Ubellularia californica), and mule fat (Baccharis salicifolia). -----and-----

"Sycamore riparian woodlands occur throughout the mountains. They are easily recognizable by the dominance of this species and a variety and abundance of other plant species, such as poison oak. A rich community, sycamore riparian woodlands are the most diverse riparian community in the Santa Monica Mountains.

We advocate for the maximum protection of native indigenous plant species and are committed to science-based and ecologically-sound land management practices. Las Flores Creek Sanctuary founder and steward is a member of the California Native Plant Society and The Theodore Payne Foundation. Other consultants include members of the Resource Conservation District of the Santa Monica Mountains, Leave No Trace, and Heal The Bay. Santa Monica Mountains Local Implementation Program guidelines are followed for the most protective and best land use management practices in this highly environmentally sensitive area.
BEST PRACTICES: Any plants included into the protected habitat meet all of our following strict guidelines:
1.They are native species to the rural coastal environment of the Santa Monica Mountains.
2.They are appropriate to the riparian and woodland habitat.
3.They are supportive of the entire health of the watershed.
4.They are strategically placed to support creek preservation (such as consideration of shading and soil stability). NOTE: No creek alteration, restoration or enhancement involved).
5.They are not nursery-produced hybrids or “selections”.
6.They are not from commercial wildflower mixes.
7.They are chosen and arranged for fire safety/wildfire resistance (such as the use of perennial native grasses instead of annual grasses and the strategic placement of fire resistant species). They are compatible with the City of Malibu, County of Los Angeles Fire Department and Department of Public Works Building and Safety Codes, Standards and Guidelines.
8.They include special consideration of endangered and rare species.
9.They are relevant to the support of native wildlife (such as the use of narrow leafed milkweed to support Monarch Butterflies and the inclusion of bird-friendly vegetation).
11. They may be relevant to the early cultural history of the region (such as the inclusion of Chumash medicinal plants).
12. They may also include plants for human educational value and passive recreational enjoyment (such as native indigenous flowering plants).


Additional Resources used:
Recommended List of Native Plants for Landscaping in the Santa Monica Mountains (by the California Native Plant Society)
“Flora of the Santa Monica Mountains, California” by Raven, Thompson and Prigge, Southern California Botanists Special Publication No. 2
“Flowering Plants - The Santa Monica Mountains Coastal & Chaparral Regions of Southern California” by Nancy Dale
“Wildflowers of the Santa Monica Mountains” by Milt McAuley
“S.A.F.E. Landscape Southern California Guidebook: Sustainable and Fire-Safe Landscapes In The Wildland Urban Interface”
California Invasive Plant Council
“Chumash Ethnobotany - Plant Knowledge Among the Chumash People of Southern California” by Jan Timbrook
“Healing with Medicinal Plants of the West” by Cecelia Garcia and James D. Adams, Jr.