Humidity and an abundance of light in the tropical and subtropical zones have evolved plants with grand and spectacular foliage in unusual patterns, with flowers a rainbow of colors, often with haunting fragrance, especially at night, according to Dr. Alfred B. Graf.

It is exciting, he says, that most of these plants can be grown quite well under conditions very different from their native home. Most species can adapt to other surroundings; in fact, it would be a challenge to try them.

"I have found that plants used in gardens are apt to be very similar in all warm-climate regions and many may be adapted to widely varying conditions - outdoors or on the patio where climate permits, and indoors where they may not survive the cold of winter."

In fact, many of the tropical foliage plants are now grown as annuals in summer gardens.

Graf is a widely traveled plant explorer of the world's tropics and subtropics. Horticulturist, botanist, and professional photographer, he is headquartered at the Exotic Nurseries of the Roehrs Co. where he has presided over one of the world's most complete plant collections.

He is the author of a new book, "Tropica," published by Scribner's, 1,120 pages, 7,000 photos showing the best of the tropical plants, $115.

It is, in fact, an encylopedia with instructions on how to care for plants in the home, office or greenhouse, how to take care of blooming plants received at holidays, plant descriptions with photo index and climate guide, propagation methods, pest control and diseases, orchids, bromeliads, cacti and succulents.

Trees have many beneficial effects, according to Dr. P. P. Pirone, plant pathologist emeritus, New York Botanical Garden. They provide cool shade during hot summer days, they add to the beauty and to the value of a property, they cut noise pollution by acting as barriers to sound and they help keep a house warmer in winter and cooler in summer.

Pirone is the author of a very fine book on who to care for trees, "Tree Maintenance," published by Oxford University Press, 584 pages, illustrated, $24.95. It is a completed revised 5th edition of his book first published in 1941, updated to cover the ecological and environmental changes that have taken place.

Featuring descriptions of all phases of tree care, the book is a basic guide to tree care, and covers planting and transplanting, pruning and treatment of wounds, fertilizers, storms and diseases and insect pasts.