Guide to Estimating Irrigation Water Needs of Landscape Plantings

Appendix B—
Invasive Species
Certain species, if grown adjacent to wildland areas,
have the ability to “invade” native habitats to
the detriment of the native species. Others cause
problems in managed landscapes. Species of both
types are listed here. It is incumbent on landscape
architects, designers, and managers to learn which
plants are considered to be invasive, and use appropriate
caution in their use.
Invasive species are indicated on the list by ☹☹,
or ☹.
Examples:
☹☹ Arundo donax
Considered an important wildland weed (can
displace native species in natural communities
in one or more regions).
☹
Acacia decurrens
Considered a wildland weed of secondary importance,
or is potentially invasive, or is a species
which is limited to one region, landscaped
areas or roadsides.
☹☹ Genista spp.
NOT ALL Genista species are considered invasive.
Refer to “Notes on Invasive Species”
for information about Genista monspessulanus
French broom.
Notes on Invasive Species
Acacia baileyana—mainly near habitations
Acacia dealbata—Northern coastal to southern inland
regions
Acacia decurrens—Northern coastal
Acacia longifolia—Minor threat along coast
Acacia melanoxylon—Northern coastal and inland to
southern coastal
Achillea millefolium—Coastal and inland areas in moist
places
Ailanthus altissima—Urban and natural areas around the
world
Albezia distachya—Coastal areas
Aptenia cordifolia ‘Red Apple’—Coastal zones, mainly
southern
Arctotheca calendula—Northern and southern coastal
bluffs, foothills
Arundo donax—All regions in moist areas, seasonal water
courses
Atriplex glauca—Southern coastal foothills
Altriplex semibaccata - Coastal to inland areas
Briza media - Grasslands
Carpobrotus edulis —Coastal and inland regional throughout
California
Carpobrotus chilensis — Coastal and inland regional
throughout California
Centranthus ruber—Coastal, inland and foothill regions
throughout California
Cistus ladanifer—coastal sage scrub and chaparral
Coprosma repens—Only coastal
Cordyline australis—Only coastal
Cortaderia sellowana—Coastal regions, dunes, scrub and
Monterey pine forest
Cotoneaster pannosus—Disturbed sites, many communities,
central and northern coast
Crataegus monogyna—Central and northern coast
Cupressus macrocarpa—Northern coastal
Cytisus canariensis—Foothill regions, northern California
and Central Valley
Cytisus racemosus—Foothill regions, northern California
and Central Valley
Cytisus scoparius—Coastal scrub, oak woodland
Cytisus striatus—Coastal scrub, oak woodland
Delosperma spp. —Potential threat on coast
Duchesnia indica—Potential threat on coast
Echium candicans (fastuosum)—Coastal
Elaeagnus angustifolia—interior riparian areas
Erica lusitanica—possible threat to wildlands
Eucalyptus camaldulensis—Southern coastal canyons and
foothills
Eucalyptus globulus—Coastal canyons and foothills,
riparian areas
Eucalyptus pulverulenta—Southern coastal
Ficus carica—Central Valley, south coastal and Channel
Islands riparian woodlands
Genista monspessulanus—Coastal scrub, oak woodland
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