THE BOOK ON MAINTAINING A BEAUTIFUL GARDEN.

Byline: JOSHUA SISKIN

The moment you open ``Flora,'' a recently published plant encyclopedia, you will realize that life is just not long enough to plant everything your heart desires. You may also conclude that this is the last plant book you will need to add to your horticultural library for quite some time.

``Flora: A Gardener's Encyclopedia'' (Timber Press; $99.95) is a two-volume set more than 1,500 pages in length. There are more than 20,000 plant photographs here, including pictures of more than 70 salvia, 200 narcissus, 200 iris, 500 camellia and 1,000 rose varieties, as well as species you probably never heard of but, once you see them, will wish you could plant in your garden.

For instance, consider Brunfelsia maliformis, a yellow flowering relative of the popular shrub known as yesterday-today-and-tomorrow (Brunfelsia pauciflora) because its flowers turn from purple to lavender to white in a matter of days. The creamy yellow Brunfelsia pictured in ``Flora,'' if and when it is locally available, would provide a breathtaking contrast to the more-familiar purple Brunfelsia. This yellow Brunfelsia has been grown in the Huntington Botanical Gardens in San Marino so we know it is suitable to our area. By the way, the flowers of all Brunfelsias are highly fragrant, and all their plant parts, being rich in alkaloids, are toxic.

Or take the green bottlebrush (Callistemon viridifolius), a stunning shrub from Tasmania that would thrive wherever the common red bottlebrush (Callistemon citrinus) grows. The green bottlebrush has luminescent greenish-yellow flowers and new foliage whose underside is flushed with pink.

A group of plants closely related to bottlebrushes are the melaleucas. Melaleuca flowers appear as half-size to miniature bottlebrushes, some of them resembling fuzzy caterpillars. In ``Flora,'' you will be introduced to white-and-violet-flowered, gold-stamened melaleucas and wonder why these tall shrubs to medium-size trees, native to an Australian climate much like our own, are not more frequently encountered in our local nurseries.

Speaking of climates like our own, it seems that we are on the verge of a ``pincushion revolution,'' the result of increasing attention lavished on a singular genus of plants from South Africa. Pincushions, botanically classified in the genus Leucospermum, are sprouting up in gardens from Santa Monica to La Canada, desiring little more than well-drained soil to display their global inflorescences and leathery leaves. More adventurous gardeners, who know how to acidify their soil with peat moss, should try proteas, a related group of South African shrubs.

Although they can be a challenge to get growing, once established these plants require no care other than the delightful task of harvesting their unforgettable blooms. ``Flora'' offers a pictorial introduction to pincushions and proteas that will make you think seriously about growing these plants.

``Flora'' is an encyclopedia for active gardeners as opposed to armchair horticulturists. For each plant group or genus, as well as in the case of many individual species and varieties, valuable information regarding soil and pruning requirements is provided. In addition, you will learn how and in what season to propagate each of the plant types included in these volumes.

Finally, a CD-ROM is included that will not only allow instant access and identification of thousands of species but also provide design guidance in coordinating planting selections by flower color, light exposure and climate zone. If your focus is fragrant, dry garden, water garden, bird-attracting, medicinal, edible or container plants, the CD-ROM will have a plethora of planting suggestions to offer you.

TIP OF THE WEEK: If you want to harvest peas this winter and spring, now is the time to plant them. They need to be growing well before the cold weather arrives. In the Valley, you simply cannot plant peas in the spring because the heat is upon us before their pods can develop. Try any of the sugar peas, which can be eaten raw, for a sweet snack every time you step into the garden two, three and four months from now.