IN THE GARDEN BOTANICAL VARIETY IS THE SPICE OF GARDENING LIFE.

Byline: JOSHUA SISKIN

For years, accepted wisdom held that we humans normally use only 10 percent of our brains. Recent research on the subject of brain utilization, however, considers this statistic a myth and maintains that we may, in fact, regularly use up to 100 percent of our brains, if not always in the most meaningful and productive ways.

Where plant selection in our gardens is concerned, however, we can confidently state that not only are less than 10 percent of existing plant species used, but a mere 1 percent of them, if not fewer, are regularly encountered around the neighborhood. Estimates of the number of existing plant species range from 250,000 to half a million. Not only would you need a botanical garden-size yard to fit in 1 percent (or several thousand species), but you'd also have to have at your disposal a network of gardeners and nursery operators throughout the world to supply you with the plants. These plants, while considerable in number, would also have to meet the requirements of your particular climate and soil type.

One of the great delights of hanging out at gardens, plant sales and nurseries is the element of surprise. You never know when you will come upon a plant that you have never seen. In the nursery at the Northridge Target store, for instance, I just discovered a plant of irresistible charms. The tag on it says Euryops virgineus. Anyone in the Valley with even a passing interest in plants has seen the more common Euryops pectinatus species over the years. This more common Euryops (YOO-ree-ops) is a bush with either sea green or gray foliage, finely cut, that is covered with yellow daisies 1 inch in size on and off throughout the year. Now picture this plant, if you can, with miniature leaves and flowers and, voila, you have Euryops virgineus. Its flowers and leaves are about one quarter the size of the familiar Euryops shrub. Euryops virgineus is supposed to bloom nonstop throughout winter and spring and eventually reach a height of 6 feet.

Speaking of new plants, I just received a most remarkable plant catalog from Heronswood Nursery (www.heronswood.com), [phone], located in Kingston, Wash. I am familiar with only a few of the dozens of specimens pictured in the catalog. There is a new lily of the Nile, Agapanthus praecox 'Two Times Blue,' that has two layers of petals in every flower, referred to as a ``double'' in horticultural lingo. You can also find Agapanthus 'Mood Indigo,' introduced by the L.A. County Arboretum in Arcadia, which has dark violet flowers that hang like bells. Lily of the Nile blooms in late spring and early summer and, as a cut flower, does well in vase arrangements.

You will also find Acanthus mollis 'Holland's Gold' in this catalog. Acanthus is often seen in shady locations or northern exposures in older gardens. It is easily recognized by its gigantic, deeply cut leaves, the same foliage sculpted at the top of those Greek Corinthian columns. 'Holland's Gold' has shimmering gold leaves instead of the glossy green foliage of ordinary Acanthus.

Among the plants most suitable for Valley gardens and container plantings are begonias, and we owe it to ourselves to experiment with all available types, including Heronswood's Begonia sutherlandii. Imagine uncontrollable mounds of light green foliage topped with pastel orange flowers and you will appreciate this sprawling species.

Two boxwood varieties in the catalog will not be found growing along most beaten garden paths. Buxus microphylla var. japonica 'National' grows into an 8-foot-tall column, while Buxus sempervirens `Elegantissima' is a 5-by-5-foot shrub with unique silver-edged foliage, appearing as though it produced a continuous display of glistening flowers.

TIP OF THE WEEK: When experimenting with a new plant about whose proper care and placement you know little, it is wise to provide a partial or half-day sun exposure. During their first year in the garden, most plants can be moved around without any risk. If your plant languishes, change its position. Just keep in mind that it can take several years for some plants to acclimate to your garden and really start to bloom.