October 5, 2013
Remember that old flame, the one who eventually drove you mad? You were drawn in by those seductive eyes, but looks were deceiving. What started as an innocent romance morphed into obsessive phone calls and a whole lot more together time than you wanted or needed. You felt smothered. Powerless. It was a fatal attraction.
That's how it is with invasive plants: they lure us in and then create havoc. We ask ourselves how something so beautiful - or, on the other hand, so ordinary - could become such a nuisance.
Ever tried to get rid of ivy? How about morning glory? Like vixens, those alluring purple flowers are hard to ignore at the nursery. Pick me, they say. But the love affair ends when those cablelike runners start prying shingles off the exterior of your house. Party's over. Time for a new vine. Only, what's this? You clip and tug and dig, but that vine won't be leaving anytime soon.
Hint: don't choose Morning Glory's sidekick, pink jasmine (Jasminum polyanthum). Opt instead for the tamer bower vine (Pandorea jasminoides).
But there's much more to the story than that — especially when viewed on a statewide level. Invasive plants cause serious economic and ecological damage as well as being annoying. They reduce livestock forage, increase the risk of fire and flooding, interrupt recreational activities, lower land value, choke waterways, and jeopardize animal and human health.
Sadly, they also crowd out the native plants that give each area of California its own unique look and feel. (One need only take a walk on Larkspur's King Mountain, where a more apt name might be Broom Mountain.) This change occurs because the native species can't compete or the environment becomes altered because of the invading plant. Soil fertility and stabilization shifts. The availability of light declines. The birds and the bees don't like the new fare so flutter elsewhere, leaving the bigger critters hungry. The biggest thug in the forest wins.
But this isn't you, right? You always know what you're planting. You've checked the list of California's noxious plants. You trust that your local nursery would never sell you something like this. You've never had a plant turn on you. Yeah, me neither.
Thirty-seven percent of the species listed on the California Invasive Plant Council Inventory were accidentally introduced. That means an unsuspecting soul picked up a rogue seed on a shoe or hoof, an immigrant packed seeds in his suitcase, a tractor dug up a buried seed, or packing material from heaven-knows-where contained a little sprout. The rest - 63 percent - were intentionally introduced, mostly through nurseries. See? It's not all your fault.
So what should a responsible gardener do? Learn which plants to avoid (and
always rely on botanical - not common - names.). This is easier than it sounds, thanks to excellent resources like the California Invasive Plant Council's "Don't Plant a Pest" website (cal-ipc.org/landscaping/dpp/).
Here are some common plants to avoid and some good alternatives to consider:
- Ice plant (Carpobrotus edulis): No, this is not part of the coastal scrub plant community. Plant dewflower or rosea iceplant (Drosanthemum floribundum) instead.
- Periwinkle (Vinca major): Spreads rapidly and smothers others. If you want a colorful, easy groundcover, consider freeway daisies (Osteospermum fruticosum).
- Purple Pampasgrass or Jubatagrass (Cortaderia jubata or Cortaderia selloana): Tiny seeds can be carried up to 20 miles. Reduces wildlife habitat and creates a fire hazard. Opt for Lindheimer's Muhly grass (Muhlenbergia lindheimeri), a large, dependable grass with blue-gray foliage. It develops large flower spikes in fall and winter. Good in lousy soil.
- Broom (any kind - Retama, Genista, Cytisus, Spartium): Brooms have invaded over a million acres in California and created serious fire hazards in residential areas. Flowers produce thousands of seeds and entire plant communities have been wiped out. If it's yellow flowers you're after, opt for Jerusalem sage (Phlomis fruticosa) or Japanese kerria (Kerria japonica) or forsythia (Forsythia x intermedia).
- Cotoneaster (Cotoneaster lacteus or Cotoneaster pannosus): Often used for median strips and along freeways. Birds have spread the berries into wildland areas. If it's berries you're after, consider Toyon (Heteromeles arbutifolia) or Redberry (Rhamnus crocea) instead.
- Blue gum eucalyptus (Eucalyptus globulus): Common along the coast. Extremely flammable (remember the East Bay hills fire of 1991?). Choose one of California's striking native trees instead, such as the Catalina Ironwood (Lyonothamnus floribundus asplenifolius).