GARDENING : OVERLOOKED L.A. AREAS SEEN THROUGH HORTICULTURIST'S EYE.

Byline: Joshua Siskin

Until last Sunday, nearly 15 years had passed since I had seen a dogwood tree.

In 1984, I spent several months setting traps for fruit flies in South Central and East Los Angeles. If you recall, the Mediterranean fruit fly had become a major threat to California agriculture, and Los Angeles was identified as a principal point of entry for this insect. Fruit flies came to the L.A. area in mangoes and other fleshy fruit or hitched rides on airplanes before settling into our local fruit trees.

South Central and East Los Angeles never have been accorded the horticultural acclaim they deserve. These parts of our city have been the subjects of film and song, but not because of the incredible diversity of their neighborhoods. Someone should compose a hymn to the deep sandy soil and perfect climate - from the standpoint of raising vegetables, fruit trees and a whole host of landscape ornamentals - found in the subtropical hinterland of Los Angeles.

And then one summer afternoon - I think it was in Cudahy - I saw a dogwood, the first dogwood I had seen since becoming horticulturally conscious. Horticultural consciousness is reached when a person begins to notice the difference between one plant and another. This is a moment of awakening, but it's also a kind of curse. Like so many other leisure-time pursuits, distinguishing between one plant and another - and remembering each plant's Latin name - soon can become an obsession. Show me someone who must know the Latin name of every plant and I'll show you someone with at least a smidgen of an emotional disorder.

Dogwood is one of the triumvirate of spring bloomers - the other two being forsythia and lilac - which transplanted Easterners never can forget, no matter how many decades they have called Los Angeles home. But dogwood struggles to grow here, chiefly due to its susceptibility to more than 50 kinds of fungi, be they saprophytes of leaf, stem or root. Root fungus generally is the bane of dogwoods planted in Southern California, since these trees demand the same quick-draining, acid soil that azaleas, for example, require - the opposite of the soil found in many of our alkaline, desertlike backyards.

This winter, which was colder than the average Los Angeles winter, has given us more blooms than usual on the lilacs and forsythias that may be spotted here and there. It also has shown off the dogwood in the backyard of Margaret and Robert Davis in a most floriferous way.

In 1964, Margaret Davis dug a dogwood seedling out of her parents' back yard in Port Jervis, N.Y. She put it in a shoe box and transported it back to Sherman Oaks, where she had moved a few years earlier. Today, that dogwood is just over 20 feet tall with an even, horizontal branching structure suggestive of a pagoda.

Davis does not have a sprinkler system on her property. This helps explain the longevity of her dogwood, which, quite frequently, succumbs to root fungus infections due to standing water. Davis does have a well-drained soil, but taking the time to water by hand, I think, has much to do with her success.

Over the years, I have discovered that people with healthy, long-lived plants are loathe to water them more than is absolutely necessary. Davis has a comely pink rosebush that she bought at a Ralphs market 40 years ago for 39 cents. It is quite rare for roses, in our area, to look as good as Davis' specimen after 40 years. In fact, most roses virtually cease to produce flowers after 10 to 15 years in the ground. This short productive life is no doubt attributable to the constant watering that roses receive in our careless use of automatic sprinkler systems.

The botanical name of dogwood is Cornus, which comes from the word carnelian, a reddish quartz-like mineral. Some species of Cornus do indeed have red bark. What many call flower petals on this tree actually are bracts, modified leaves that give plants such as bougainvillea, rosemary and shrimp plants their color. On dogwoods, the actual flower is a nondescript button in the middle of the bracts. Bracts are white (as on Davis' tree), pink or red. Two California native dogwoods can be grown in our area: Cornus nuttallii and Cornus stolonifera. The latter has red twigs.

The name dogwood, sometimes interchanged with dogberry, has two possible derivations. The bark, which contains a type of quinine, was used at one time for washing mangy dogs. Also, the berries of this tree are so bitter that one authority described them as ``not fit to be given to a dog.''

Tip of the week: One of the dominant flowers in Davis' garden is the gloriosa daisy or black-eyed Susan (Rudbeckia hirta). This species self-sows and thrives in full sun on little water. Plant a packet of gloriosas now for flowers during summer and fall for years to come.