The World Flora Online

Arbres de petite taille, arbustes ou herbes terrestres ou aquatiques, généralement des eaux douces, glabres ou à poils simples. Stipules absentes. Feuilles alternes, opposées ou verticillées, sessiles ou pétiolées ; limbe entier à profondément découpé, à marge entière à dentée. Inflorescences axillaires ou terminales, en panicule, racème, fascicule ou à fleurs solitaires, les partielles généralement en cymes dichasiales. Fleurs actinomorphes, 2- à 4-mères, bi- ou unisexuées (et dans ce cas espèces monoïques) ; sépales valvaires, parfois absents ; pétales imbriqués, carénés ou cucullés, parfois absents ; étamines 4 ou 8, à filets courts, anthères à déhiscence par fentes longitudinales ; ovaire infère, (1- à)4-loculaire, avec un ovule par loge ou bien deux dont l’un avorté ; styles 1 à 4, libres, stigmates parfois sessiles, papilleux ou plumeux. Fruits : nucules avec 1 à 4 graines, schizocarpes déhiscents généralement en 4 méricarpes, ou bien indéhiscents avec 4 pyrènes, l’extérieur souvent tuberculé, côtelé ou ailé. Graines à albumen abondant.

Famille avec dix genres et environ 140 espèces, distribuée dans les régions tempérées, subtropicales et tropicales du monde entier, mais avec le centre de diversité en Australie. En Afrique tropicale, on trouve deux genres : Laurembergia et Myriophyllum. Au Gabon, seulement une espèce de Laurembergia a été observée.

Herbes'ou suffrutex, aquatiques ou terrestres, monoïques ou dioïques.'Feuilles'sans stipules, alternes, opposées, verticillées ou toutes radicales, parfois très petites, simples, entières ou ± divisées, surtout les immergées.'Inflorescences'axillaires ou terminales, en cymes, fascicules, racèmes, particules d'épis, ou fleurs solitaires; bractées souvent présentes.'Fleurs'parfois bractéolées, généralement petites, ☿ ou ♂♀, actinomorphes ; calice à tube adné à l'ovaire, à 2-4 lobes valvaires, parfois rudimentaires ou nuls; pétales 2(3)4, valvaires ou légèrement imbriqués-contortés ou absents; étamines (1)2-8; filets longs ou courts; anthères basifixes, à 2 loges déhiscentes par fente latérale; ovaire infère, arrondi ou anguleux à ailé, 1-4-loculaire; loges 1-ovulées; ovule apical, pendant, anatrope, à 2 téguments; styles 1-4, libres ou nuls; stigmates papilleux ou plumeux.'Fruits': nucules ou drupes arrondies, anguleuses, côtelées ou ailées, à 1-4 loges monospermes, ou divisées en 2 ou 4 coques monospermes.'Graines à albumen charnu, abondant.\n\t\t\tFamille des régions tempérées, subtropicales et tropicales comprenant 7 genres et environ 130 espèces; pour la Flore, 2 genres et 2 espèces, l'une représentée par 2 variétés, l'autre par 1 sous-espèce réunissant 3 variétés.

Seeds pendulous, with copious endosperm and straight fairly large (rarely small) embryo Fruit small, a nut or drupe, sometimes winged, indehiscent or rarely breaking up into cocci Ovary inferior, 1–4-celled; styles 1–4; ovules as many as the styles, pendulous from the apex of the cells Stamens 2–8, rarely 1, large; anther basifixed, 2-celled, opening lengthwise Petals 3–4 or absent, valvate or slightly imbricate Calyx-tube adnate to the ovary; lobes 2–4 or absent Flowers hermaphrodite or unisexual, solitary to paniculate or corymbose, often very small Herbs or undershrubs, often aquatic; leaves alternate, opposite or verticillate, sometimes very large, the submersed ones often much divided; stipules absent Fruit small, a nut or drupe, sometimes winged, indehiscent or rarely breaking up into cocci Ovary inferior, 1–4-celled; styles 1–4; ovules as many as the styles, pendulous from the apex of the cells Stamens 2–8, rarely 1, large; anther basifixed, 2-celled, opening lengthwise Petals 3–4 or absent, valvate or slightly imbricate Calyx-tube adnate to the ovary; lobes 2–4 or absent Flowers hermaphrodite or unisexual, solitary to paniculate or corymbose, often very small Herbs or undershrubs, often aquatic; leaves alternate, opposite or verticillate, sometimes very large, the submersed ones often much divided; stipules absent

Petals 2–4, valvate or ± imbricate, or absent Calyx-tube short, adnate to the ovary; calyx-lobes 2–4, mostly valvate and persistent, or absent Inflorescences axillary or terminal, the flowers usually small, arranged in cymes, fascicles, racemes, panicles or spikes, or solitary; bracts often present Leaves alternate, opposite or verticillate, pinnately or palmately nerved, sometimes very large, the submerged ones often much divided; stipules absent Seeds with abundant fleshy or oily endosperm Fruit a nutlet, indehiscent or breaking up into 2 or 4 single-seeded mericarps, or a drupe Gynoecium 1–4-locular; ovules 1 in each loculus, pendulous from the apex; styles 1–4 or absent; stigmas papillose or plumose Stamens 2, 3, 4 or 8, rarely 1 or absent; anthers basifixed, 2-celled, dehiscing lengthwise; filaments mostly filiform Herbs or undershrubs, often aquatic, monoecious, polygamous or dioecious Calyx-tube short, adnate to the ovary; calyx-lobes 2–4, mostly valvate and persistent, or absent Inflorescences axillary or terminal, the flowers usually small, arranged in cymes, fascicles, racemes, panicles or spikes, or solitary; bracts often present Leaves alternate, opposite or verticillate, pinnately or palmately nerved, sometimes very large, the submerged ones often much divided; stipules absent Seeds with abundant fleshy or oily endosperm Fruit a nutlet, indehiscent or breaking up into 2 or 4 single-seeded mericarps, or a drupe Gynoecium 1–4-locular; ovules 1 in each loculus, pendulous from the apex; styles 1–4 or absent; stigmas papillose or plumose Stamens 2, 3, 4 or 8, rarely 1 or absent; anthers basifixed, 2-celled, dehiscing lengthwise; filaments mostly filiform Herbs or undershrubs, often aquatic, monoecious, polygamous or dioecious

Fls epigynous, regular, bibracteolate, 3- or 4-merous, mostly small and anemophilous; sep valvate, persistent; stamens as many or twice as many as the sep, with short filament and large anther; ovary with 3 or 4 carpels and locules and distinct, feathery styles, each locule with a solitary, pendulous ovule; fr small, nut-like or drupaceous, sometimes separating into mericarps; embryo straight, cylindric, dicotyledonous, embedded in the soft endosperm; exstipulate herbs (some extralimital genera woody), often aquatic. 8/100.

Herbs perennial, rarely annual, aquatic or terrestrial, monoecious or dioecious. Stem creeping, ascending or erect, often rooting at lower nodes. Leaves estipulate, 2-4-whorled, decussate, or alternate, in terrestrial species always simple, in aquatic submersed species always pectinately lobed. Inflorescence an indeterminate or determinate spike of 1-5-flowered dichasia borne in axils of leaflike primary bracts; occasional lateral inflorescences simpler. Flowers minute, actinomorphic, epigynous, protandrous, anemophilous or entomophilous, bisexual or unisexual. Sepals (2-)4, but absent in female flowers of some Myriophyllum, mostly persistent. Petals alternisepalous, (2-)4, absent in female flowers of some Myriophyllum, imbricate, longer than sepals, often deciduous with stamens. Stamens 1 or 2 × as many as sepals; filaments short, slender; anthers basifixed, mostly oblong or linear, 4-loculed, dehiscing by slits, antisepalous anthers sometimes somewhat longer than antipetalous ones; pollen grains shedding at 3-celled stage. Ovary inferior, 1(or 2)- or 4-celled, septa solid or practically absent (present only at base and apex of ovary); styles as many (rarely half as many) as sepals, alternisepalous, free, mostly short, grading into globose or subulate stigmas, spreading in fruit; stigmatic papillae hairlike; ovules as many as styles, rarely 1, apical, pendulous, anatropous. Fruit nutlike or a drupe, variously ornamented with wings, ribs, and tubercles, indehiscent and 1-seeded or breaking up into (2-)4 1-seeded mericarps; pericarp membranous or endocarp woody; exocarp membranous or swollen and spongy. Seeds with thin testa; embryo cylindric, surrounded by thick, white albumen.

Inflorescences axillary or terminal, the flowers in cymes, fascicles, racemes, panicles, spikes or solitary; bracts often present Leaves usually exstipulate, alternate, opposite, whorled or all radical, sometimes very small, the blades simple, entire or ± divided especially in the case of submerged leaves Aquatic or terrestrial herbs or subshrubs with hermaphrodite, monoecious or dioecious flowers Stems (1–)2–8; filaments long or short; anthers basifixed, 2-thecous, dehiscing by lateral slits Ovary inferior, rounded or angular to winged, 1–4-locular; locules 1-ovulate; ovule apical, pendulous, anatropous; styles 1–4, free or absent; stigmas papillate or plumose Calyx with the tube adnate to the ovary; lobes 2–4, valvate, sometimes rudimentary or absent Petals 2(–3)–4, valvate or slightly imbricate-contorted, or sometimes absent Flowers often bracteolate, usually small, regular Seeds with abundant fleshy albumen Fruit a nutlet or drupe, bluntly angular, ribbed or winged with 1–4 1-seeded locules or divided in 2 or 4 1-seeded cocci Leaves usually exstipulate, alternate, opposite, whorled or all radical, sometimes very small, the blades simple, entire or ± divided especially in the case of submerged leaves Aquatic or terrestrial herbs or subshrubs with hermaphrodite, monoecious or dioecious flowers Stems (1–)2–8; filaments long or short; anthers basifixed, 2-thecous, dehiscing by lateral slits Ovary inferior, rounded or angular to winged, 1–4-locular; locules 1-ovulate; ovule apical, pendulous, anatropous; styles 1–4, free or absent; stigmas papillate or plumose Calyx with the tube adnate to the ovary; lobes 2–4, valvate, sometimes rudimentary or absent Petals 2(–3)–4, valvate or slightly imbricate-contorted, or sometimes absent Flowers often bracteolate, usually small, regular Seeds with abundant fleshy albumen Fruit a nutlet or drupe, bluntly angular, ribbed or winged with 1–4 1-seeded locules or divided in 2 or 4 1-seeded cocci