A Revision of Octamyrtus (Myrtaceae)

Abstract

differs from Rhodomyrtus and other genera of Myrtaceae in the increased number of petals, six, eight or twelve (as against four or five in Rhodomyrtus), which in Octamyrtus are very showy, unequal and strongly imbricate in the bud but enlarge rapidly to up to 6 cm long. Octamyrtus Diels in Engl., Bot. Jahrb. 57: 373 (1922). Shrubs or small trees. Leaves opposite, often large, petiolate, pinnatinerved, villous or tomentose. Flowers large, solitary or in 3-flowered dichasia, axillary or in cauliflorous clusters; bracteoles small and deciduous or leafy and persistent, ovate or lanceolate. Calyx campanulate or turbinate, hypanthium not produced above the ovary, calyx-lobes 4, broad, herbaceous, persistent, unequal. Petals 6, 8 or 12, free, white, pink or red, markedly unequal, strongly imbricate in bud. Stamens numerous in 4--6 series, free, not clustered, incurved near the apex when in bud, finally exserted, filaments filiform, anthers basifixed with parallel cells opening longitudinally. Ovary 4(-7)-locular, with many ovules in 2 series on 4 axile placentas. Style columnar, stigma capitate. Fruit a globose or oblong dry berry. Seeds numerous, compressed-reniform, horizontal in c. 10-30 rows separated by woody to chartaceous, vertical and horizontal false septa, so that the fruit appears to be 8-locular with the seeds in individual compartments. Testa crustaceous, embryo pimentoid (horse-shoe shaped, with a long radicle and short cotyledons). Lectotype species: 0. insignis Diels; McVaugh in Taxon 5: 144 (1956).