GARDENING : WHY TORREYS ARE PINING FOR THEIR NATIVE SURROUNDINGS.

Byline: Joshua Siskin

The most majestic tree in Los Angeles just might be the Torrey pine (Pinus Torreyana) that grows in the Mildred Mathias Botanical Garden on the campus of UCLA. Yes, I know there are spectacular oaks, formidable examples of which may be found at Orcutt Ranch in Chatsworth. And there is a rose gum (Eucalyptus grandis) and a floss silk tree (Chorisia speciosa) - also in the UCLA garden - that are without equal in our city. But there is something about this Torrey pine.

Standing beneath this tree, which must be more than 60 feet tall, you are overcome with feelings of reverence and gratitude. You feel reverence for the divine inventor, creator and sustainer of such a miraculous work of arboreal art. You feel gratitude to the prescient person who, decades ago, planted an unassuming seedling that somehow grows into this awe-inspiring pine.

And yet, the person who planted this pine probably was not a prophet. There's no way the stature it has attained could have been foreseen.

Typically, our greatest triumphs in the garden happen almost by accident. We go to the nursery looking for azaleas and, instead, bring home blue-flowering ``Jungle Beauty'' ajuga, orange-flowering ``Gartenmeister'' fuchsia, and ``Myers'' fox-tail asparagus. The combination of these three shade-loving plants turns out to be perfect. Or we plant low-growing, cerulean blue-blooming Burmease plumbago (Ceratostigma griffithii) next to violet-blooming Mexican sage (Salvia leucantha) because they are the only fall bloomers available on our November visit to the nursery. Several years later, these two plants complement each other in such extraordinary ways that everyone who visits our garden swears that we must be geniuses in the art of landscape design.

The Torrey pine is appropriately named after John Torrey, one of the two or three greatest botanists America has known. This tree is unique, and carefully watched, for several reasons. It is the only pine indigenous to the coast of Southern California, and the only pine whose seeds germinate while still in their cones, and the rarest pine - in terms of numbers - on the entire North American continent. It is native to only two areas: the coastal bluffs flanking Soledad Valley in San Diego County and Santa Rosa Island (one of the Channel Islands).

Because Torrey pines are confined to such limited areas, there is little genetic variability in their seeds. This means that an environmental catastrophe, such as that brought on by drought, insects or disease, quickly could decimate much, if not all of the species. In addition, these pines are very sensitive to air pollutants, a real problem since the trees near San Diego are affected by that city's air pollution, and the trees on Santa Rosa Island absorb easterly Santa Ana winds that carry pollutants all the way from Los Angeles.

Ironically, a significant threat to the future of Torrey pines in their native surroundings is their carefully monitored status. Absent the kind of enormously destructive fires that once occurred on a regular basis - but aren't allowed anymore due to the proximity to people and houses - these trees may not be capable of survival. In a single day or two, fire may kill all the adult trees in the Torrey pine forest, but fire also causes thousands of Torrey pine seeds to germinate. Without fire, few seeds will germinate. Without a land-clearing fire, seedlings that do manage to grow probably will not reach the age of seed production (which occurs at age 12 to 18) due to competition from the many older, taller trees around them.

Tip of the week: Observe the leaves of mulched plants for slug damage. Although mulch made from shredded leaves and wood chips is an effective deterrent to snails, it harbors slugs that chew holes in the foliage of certain ornamentals such as hydrangea, dead nettle (Lamium maculatum), and angel wing jasmine (Jasminum nitidum). Where such ornamentals are planted, use an aged compost for mulch, rather than the rougher materials mentioned above.