Some ivy species in the Hedera genus are a problem in California. They can smother understory vegetation, kill trees, and harbor non-native rats and snails. It's difficult to distinguish problem species from less invasive ones. Do not plant ivy near natural areas, never dispose of ivy cuttings in natural areas, and maintain ivy so it never goes to fruit. Researchers hope to determine which ivies can be planted safely.
This vigorous groundcover forms impenetrable mats that compete directly with native vegetation, including several rare and threatened plants. Small mammals can carry seeds of iceplant from landscape settings to nearby natural areas. Pieces of the plant can be washed into storm drains and into natural areas where they become established.
This aggressive grower has trailing stems that root wherever they touch the soil. Their ability to resprout from stem fragments enables periwinkle to spread rapidly in shady creeks and drainages, smothering the native plant community.
Forms lush compact mat 4 to 6 inches high. Glossy dark green leaves, white flowers. Mow or cut back annually to force new growth. Can be found growing along the coast from Monterey county and north to Alaska.
Grows more slowly than Vinca spp. and Hedera spp., but has a crisp, neat growth form. New foliage is bright green, changing to dark green with age. Small white flowers on 1-2 inch spikes. Withstands shade and is widely used under trees. Variegated cultivars are available. Deer resistant.
A non-invasive iceplant with smaller, succulent leaves and brilliant violet-pink flowers May through October. Salt tolerant. Fire resistant.
A low-growing, evergreen shrub with fragrant, dark-green leaves. Can tolderate full sun along the coast but needs partial shade in the hotter inland areas. Once established, evergreen current does not need irrigation and is an excellent choice for growing under native oaks where supplemental watering is discouraged.