October 3, 2009
There are 1,679 species of plants in Marin County, according to the revised edition of "Marin Flora." The California flora numbers 5,800 species, according to "The Jepson Manual: Higher Plants of California."
Most of California has a Mediterranean climate with warm, dry summers and cool rainy winters. The same climate is found in the Mediterranean regions of southern Europe and also northern Africa, southern Africa, Chile and southwestern Australia.
With our recent drought and limited water supply, many gardeners have been choosing drought-tolerant California natives for their gardens. It makes good sense: California natives are adapted to this Mediterranean climate we live in and they are adapted to the pollinators, pathogens and predators here.
Why then the sudden interest by nurseries, horticulturists and home gardeners in Australian plants? First, plants from southwestern Australia are also adapted to our California climate. Many of them are drought tolerant and deer resistant. And there are so many interesting ones from which to choose. One source says there are 20,000 species of plants in Australia, a startling difference to the 1,679 species of plants in Marin County, according to the revised edition of "Marin Flora," and the 5,800 species of California flora, according to "The Jepson Manual: Higher Plants of California."
Some Australian plants have become invasive pests in California. Most of us are familiar with eucalyptus - it is listed as an "invasive non-native plant that threatens wildlands in California." The California Invasive Plant Inventory also lists Australian saltbush, Atriplex semibaccata, as invasive. Growers, horticulturists and nurseries must act with diligence and concern to prevent the import of Australian plants that may become pest plants here.
A visit to an Australian gardens will give gardeners a better idea of how Australian plants can fit into our California landscape. You can see some fine examples of Australian plants at Falkirk Cultural Center in San Rafael. Through a joint effort of Marin Master Gardeners and the City of San Rafael, an Australian plant garden was established last November. Several species of acacia, grevillea, kangaroo paws and Australian mint bush are thriving. The Flora Grubb Gardens in San Francisco has wonderful displays of plants in the Proteaceae family: leucadendrons, grevilleas, banksias and proteas. The hot reds, vivid pinks and deep maroon colors are eye popping.
The University of California at Santa Cruz Arboretum has 30 to 40 acres devoted to Australian plants. It estimates it has 2,000 species, forms or cultivars growing. Since 1978 the Arboretum has tested several hundred species of Australian imports, many of which have now been introduced into the nursery trade.
With so many spectacular plants to choose from, it is difficult to describe just a few. But here are three popular plants from Down Under:
- Banksias are evergreen shrubs or trees. They will grow in full sun with moderate water, and good soil drainage is required. The spectacular, cylindrical clusters of flowers give way to woody seed cones. The foliage varies in different species. Plant size varies from prostrate species, to shrubs at 10 feet tall, to trees that reach 30 feet or more.
- Anigozanthos are perennials with erect, swordlike leaves. Their fuzzy tubular flowers, divided and curved at the tips, gives them their name, kangaroo paws. They grow in full sun with regular water. Foliage clumps can spread from 1 to 3 feet. Kangaroo paws prefers sandy soil, but will do well in a loose, light soil with good drainage.
- Proteas are evergreen shrubs with unusual and beautiful flower heads. The flower is actually a tight cluster of tubular flowers surrounded by colorful bracts. They make wonderful, long-lasting cut flowers for your home. These plants may not be easy for the novice to grow, because they are fussy about growing conditions.Ê Proteas need soil with good drainage; some prefer an acid soil. Protection from wind and good air circulation around plants is also important.
If you're looking for something different that will grow well with your California natives, that's colorful and exciting, try some Australian plants.