The flowering plants, known scientifically as the class Angiosperm, are the dominant group of vascular plants on earth today. They arose some 120 million years ago or more, and about 80 to 90 million years ago they had become the characteristic plants dominating most parts of the world.

There are at least 250,000 species of flowering plants grouped into 250 to 350 families. They are our main sources of food crops, timber, fibers, vegetable oils, gums, herbs, spices, flavorings, drugs, stimulants and narcotics. They also adorn our parks, gardens, streets and other public places the world over as trees, shrubs and flowers.

A new book, "Flowering Plants of the World," with V. H. Heywood as consultant editor, has been published by Mayflower Books. Its 334 pages are priced at $17.95. It describes and illustrates in full color the great majority of these plant families. It would make a wonderful Christmas gift for yourself or a friend.

The main text was written by a panel of internationally recognized authorities; Vernon Heywood, the consultant editor, is currently dean of the faculty of science and has been professor of botany and head of the department of botany at Reading University since 1968. He is also director of the plant sciences botanical garden.

The opening section of the book is an informative introduction to the forms, structure, ecology, uses and classification of flowering plants are then described, each with a concise and readable account of the distribution, diagnostic features, classification and economic uses of its members.

Every family member also has a specially designed quick-reference panel giving details of the number of species and genera, their general distribution and economic uses. The distribution is also presented visually on a map of extra clarity.

The specially commissioned color plates are not only scientifically accurate but also constitute a beautiful and unique collection of painting, according to the publisher.

Perhaps the book will help focus attention on some of the problems faced by flowering plants throughout the world and stimulate a greater appreciation of their role in our future.

One of the main problems is that most of the Angiosperm families are tropical in their distribution-about two-thirds are confined to the tropics or adjacent regions, and many are threatened with extinction.

The tropical countries are under great pressure, with population growth, energy problems, economic difficulties and inflation encouraging them to consume and in effect destroy their plant resources in a headlong race for development and survival.

Offical estimates suggest that 10 million hectares (hectare is equal to 2.471 acres) of tropical forests are being felled each year. It is calculated that at the present rate of destruction there will be no undistrubed tropical humid lowland forest left anywhere in the world by the end of this century.

Many of the plants in these tropical forests and other plant communities will be destroyed before they have even been collected and described for the first time and many others will disappear before we have had a chance to study them thoroughly and learn how best to use them.