Then suddenly they found themselves surrounded by a walnut orchard that necessitated cultivation that was foreign to them. After several years of this abuse, their root systems were severely violated by excavation for foundations and subterranean utilities of the homes that are now here, as well as the driveways, sidewalks and street. Since then, generous irrigation of the associated landscapes has promoted decay of the roots that are adapted to dry summers. Although the largest specimen next door is remarkably healthy, many of his friends have succumbed to their damages.

Gardening with native species requires some familiarity with the unique climates and soils of California that such species are adapted to. For example, natives are generally adapted to minimal precipitation and therefore prefer minimal, if any, irrigation. Many garden enthusiasts enjoy native species, and many others establish gardens within areas already inhabited by desirable native species.

Meetings of the California Native Plant Society are always open to anyone who enjoys gardening with native species and who might be interested in becoming a member. During the next meeting of the Santa Clara Valley Chapter of the CNPS, guests are invited to share photographs of their favorite specimens of native species and enjoy a slide show of pictures compiled by members. Prints, drawings and other material relevant to native species can also be shared and discussed.

This meeting begins at 7:30 p.m. on Jan. 16 at the Los Altos Library Program Room, located at 13 S. San Antonio Road in Los Altos. Anyone wishing to share pictures or slides should arrange reservations by Jan. 12 with Judy Fenerty by telephoning 408.378.6272 or sending email to judy@fenerty.com. Individual discussions should be limited to five minutes.

Plant of the Week: Christmas cactus

"Pot plant" is a horticultural slang term that designates plants forced into bloom to be enjoyed while bloom continues but then discarded because they are not expected to survive the transition from greenhouse culture to household or garden culture. Most are seasonal, such as poinsettias, Easter lilies and Dutch iris, but others, such as chrysanthemums, azaleas and hydrangeas, are available during a more extensive season. Some are certainly more likely than others to survive transition into the garden or home, and Christmas cactus, Schlumbergera bridgesii, is one of the most reliable.

Christmas cactus is best displayed—as well as more easily protected from snails—in containers from which the pendulous stems may cascade. Bright ambient sunlight is preferred, but direct exposure to sunlight may burn or discolor foliage. Irrigation should not be so frequent that roots rot in saturated soil. Potted Christmas cacti are happiest as houseplants or on sheltered porches or lanais.

Mature specimens may be as wide as 2 ¹/2 feet. The glossy, dark green foliage is actually composed of flat, jointed stems. Each segment is approximately an inch and a half long and has a few blunt "teeth." The purplish-red flowers are tubular at the base but flare in the middle, with upper petals folded back. From base to tip, each petal may be as long as 3 inches. Specimens grown on porches or lanais exposed to cool autumn weather and long autumn nights will be encouraged to bloom profusely during winter.

Crab cactus, Schlumbergera truncata, is very similar to Christmas cactus, but the stem segments have more prominent teeth and may be as long as 2 inches. Flowers are not as tubular and can be orange-red, orange-pink, orange, pink or white.

Although both species appreciate cool autumn weather, they are also sensitive to frost.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.