Haloragaceae

Abstract

Small trees, shrubs, subshrubs, or perennial or annual terrestrial or aquatic herbs, glabrous or scabrous with simple uniseriate hairs; stems erect, ascending, procumbent or creeping, often rooting at lower nodes; nodes unilacunar. Leaves opposite, alternate or verticillate, sessile or petiolate, simple or deeply dissected, entire or toothed, estipulate, heterophyllous in Proserpinaca and Myriophyllum . Inflorescence thyrso-paniculate, thyrsoid or racemose, or flowers solitary; partial in florescences usually dichasial; prophylls persistent or caducous. Flowers regular, hermaphroditic or unisexual-monoecious, epigynous, 4(-2)-merous; sepals valvate, persistent (0 in female flowers of Myriophyllum); petals imbricate, keeled, hooded, ± unguiculate, falling with the stamens (0 or rudimentary in Proserpinaca and female flowers of Myriophyllum and Laurembergia); stamens equal to or twice the number of sepals; filaments short, slender; anthers 4-sporangiate, dehiscing by slits; gynoecium 4(-2)-carpellate; stylodia free, clavate, from bulbous base; ovary 4(-1)-locular but septa sometimes weakly developed and present only at base and apex of ovary or reduced; ovules 2 or 1 per loculus (if 2, then one aborts at an early stage), anatropous or hemitropous, bitegmic, crassinucellar, with weakly developed funicular obturator. Fruit an indehiscent, 4-1-seeded nutlet, or indehiscent and comprising 4 pyrenes (Meziella), or splitting septicidally into (2-)4 mericarps (Myriophyllum), the exocarp often ornamented with tubercles, wings or ribs; seeds with straight, cylindrical embryo and usually with ± copious, fleshy endosperm. x=7 (9, 21, 29). A subcosmopolitan family of 8 genera and c. 150 species, most south hemispheric, particularly Australian

Keywords

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