A FIELD GUIDE TO THE LITTLE PEOPLE, by Nancy Arrowsmith with George Moorse; illustrated by Heinz Edelmann; calligraphy by Kevin Reilly (Hill & Wang, $10). Elves and brownies are, of course, a common feature of our daily lives, as are trolls (more properly mound folk) and leprechauns. But if you think you know all about the alternate species that share our globe, this handy reference work should be an eye-opener. There is, for example, the Yugoslavian Macic, "who has a weakness for doughnuts and lives in the sea"; the Welsh Gwagged Annwn, who dance in meadows on nights when there is full moon; the Swedish Skogsnufvar whose beauty has led many men to their deaths, from mischief or from longing; the Slavic Vodyany, who drinks and gambles and eats people who drown, storing their souls under jars in his underwater palace. They are all in here with striking pictures, anecdotes and scholarly discussions of their habits and habitats, along with some details that you might not have known about nereides, hobgoblins, changelings and the will-o'-the-wisp. Although highly readable, this is also a solid reference work, with a lengthy bibliography in half a dozen languages.

PARALLEL BOTANY, by Leo Lionni; translated by Patrick Creagh (Knopf, $12.95; paperback, $5.95). What Tolkien did for linguistics, Lionni has done for the study of plants invented a whole new botanical universe, complete with evolutionary history, extinct species, legends and a variety of remarkable structures, habit, abilities - one can hardly avoid saying "personalities," so vivid is the life of some of these imaginary plants.Consider, for example, the Tirillus mimeticus, which fools its natural enemies by imitating black volcanic pebbles; the woodland tweezers, whose aggressive territorial patterns have been shown to parallel the moves in a classic game of go, the Labirintiana labirintiana, which developed maze patterns on its leaves and thus destroyed a destructive species of ant by driving its members into neurosis; the Tirillus silvador, which sometimes whistles on clear nights in January and February. He also invents quite a few people - for example, "the celebrated syndrologist Pierre-Paul Bigny, who for some years has been carrying out important research at the Sorbonne, chiefly in the hydromagnetic radiations of biomorphic fields." And whole primitive tribes and languages - for instance, the Xumi language of the Kwo'na group, in which is told the story of Pwa'ko, who bride was a moon flower. Lionni, best known in the past as a writer and illustrator of children's books (Little Blue and Little Yellow and Frederick ), has now gone to the opposite end of the literary spectrum, writing and illustrating a mockerudite parody of a scientific text that is fascinating and often hilarious.

THE CHRONICLES OF THOMAS COVENANT THE UNBELIEVER, by Stephen R. Donaldson (Hold, Rinehart & Wilson, three volumes, $10 each). In this enormous fantasy, the timeless battle of good and evil is played out against a stunningly detailed and imaginative alternate-world background - giants, cave-dwellers, intelligent horses, strange beasts, potent talismans, and men with incomprehensible powers. The hero, a modern American transported mysteriously to this strange environment, manages to make it all believable because he has trouble believing it himself. Donaldson has created a classic in his specialized field.