Where have all the flowers gone? That's the unspoken feeling of Robinboy and Robingirl in their slick new Parisian apartment (#192,768, tenth floor, stairway B, etc.). The architect has provided disposals for everything--except boredom. From the window of their ""sad pad,"" the children see a Mocking Bird (with hat, vest, shoes) who brings relief: he plants a fraxilumelle seed from Java, and the flower grows. . . like wild. Known for its TLC (rocking children to sleep, counting seconds for soft-boiled eggs, etc.), the fraxilumelle is a homegrown response to mass-produced sterility. There is, at first, some bureaucratic bafflement, but when the President of the Republic comes out to investigate the blooming things and ends up playing hide-and-seek among the petals, their sanctity is virtually assured. Cold-bright colors, however, undercut the argument for their existence: the flowers are accepted as utilitarian, even more importantly as affectionate, but the visual impact is not warm and personal. The skyscraper-high blossoms look threatening despite softer contours than the surrounding buildings, and the gentle digs in the text have no corresponding wit in the illustrations. Flower Power parable belted by the pictures.