The World Flora Online

SELECTED REFERENCES

Barker, W. T. 1986. Ulmaceae. In: Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, Kans. Pp. 119-123. Elias, T. S. 1970. The genera of Ulmaceae in the southeastern United States. J. Arnold Arbor. 51: 18-40. Giannasi, D. E. 1978. Generic relationships in the Ulmaceae based on flavonoid chemistry. Taxon 27: 331-344. Giannasi, D. E. and K. J. Niklas. 1977. Flavonoids and other constituents of fossil Miocene Celtis and Ulmus (Succor Creek Flora). Science 197: 765-767. Grudzinskaya, I. A. 1965. The Ulmaceae and reasons for distinguishing the Celtidoideae as a separate family Celtidaceae Link. Bot. Zhurn. (Moscow & Leningrad) 52: 1723-1749. Sweitzer, E. M. 1971. The comparative anatomy of Ulmaceae. J. Arnold Arbor. 52: 523-585. Zavada, M. 1983. Pollen morphology of Ulmaceae. Grana 22: 23-30.

Trees or shrubs , deciduous (sometimes tardily deciduous in Ulmus ). Bark smooth to deeply fissured or scaly and flaky; sap watery. Leaves alternate [opposite], distichous [or not], simple; stipules present; petiole present. Leaf blade: base often oblique, margins entire or serrate, crenate, or toothed; venation pinnate to palmate-pinnate. Inflorescences axillary, cymes, racemes, fascicles, or flowers solitary, arising from branchlets of previous season (e.g., Ulmus ) or of current season (e.g., Celtis ). Flowers bisexual or unisexual, staminate and pistillate on same [different] plants; sepals persistent, (1-)5(-9), connate [distinct], imbricate or valvate; petals absent; stamens usually as many as calyx lobes, hypogynous, opposite calyx lobes, erect in bud; filaments free or arising from calyx tube, distinct, curved or sigmoid in bud; anthers 2-locular, dehiscence longitudinal; pistils 1, 2(-3)-carpellate; ovary 1(-2)-locular; ovules 1 per locule, pendulous from apex of locule, anatropous or amphitropous; styles (1-)2, distinct, receptive stigmatic area decurrent on distal inner margin of style branch. Fruits fleshy drupes, samaras, or nutlike. Seeds 1; arils absent; endosperm absent to scanty, consisting of 1 layer of thick-walled cells; embryo straight or curved.

Arbres ou arbustes, parfois grimpants, parfois épineux, monoïques, dioïques ou polygames, à feuilles caduques ou persistantes, sans latex ; bourgeons munis d’écailles ou non, parfois épineux. Stipules présentes, libres ou soudées, caduques. Feuilles alternes, généralement distiques, rarement opposées (hors Afrique), pétiolées, simples ; limbe souvent inégal à la base, habituellement 3-nervé, rarement penné, à nervures qui ne terminent pas dans les dents (non camptodromes), à marge entière à serrée, habituellement avec des cystolithes. Inflorescences axillaires, racémeuses, fasciculées ou rarement réduites à une fleur, souvent précoces. Fleurs unisexuées, rarement bisexuées, peu voyantes, régulières ; tépales 4 à 6(à 8), imbriqués ou valvaires, libres ou soudés, persistants ; étamines 4 à 6(à 8), aussi nombreuses ou un peu plus que les tépales, opposititépales, anthères à 2 thèques, à déhiscence longitudinale ; ovaire supère, à 2 carpelles, à 1(ou 2) loges à 1 ovule apical et pendant, anatrope ; styles 1 ou 2, bifides, rarement entiers. Fruits drupacés, faiblement charnus, ou en samares et ± ailées ou appendiculées ; endocarpe osseux. Graines arrondies, exalbuminées ; embryon courbé ou droit.

Famille cosmopolite avec jusqu’à 16 genres et 167 espèces, dont deux genres et six espèces au Gabon.

Arbres'ou arbustes, souvent polygames, à feuilles alternes, distiques, presque toujours asymétriques, à stipules latérales, libres, généralement petites et caduques.'Fleurs'petites, ♂, ♀ ou ☿, isolées ou réunies en cymes; périanthe simple à 4-6 segments; étamines en même nombre que les segments du périanthe et opposées à ceux-ci, rarement plus nombreuses, dressées dans le bouton; ovaire supère à 1 (2) carpelle, 1-loculaire, à 1 ovule penduleux inséré au sommet de la loge ou plus bas; style divisé en 2 branches souvent divisées à leur tour.'Fruit : samare ou drupe.\n\t\t\tQuatorze genres et environ 120 espèces : 4 genres et 10 espèces au Congo belge, jouant un rôle assez important dans les forêts primaires, surtout de la périphérie de la cuvette centrale, et spécialement'Trema guineensis , dans les reboisements.

Trees or shrubs Leaves alternate, simple, often unequal-sided; stipules paired, caducous Flowers fasciculate, hermaphrodite or unisexual Calyx herbaceous, lobes imbricate, persistent Fruit usually compressed, membranous, dry or thinly fleshy, often winged or appendiculate Seed without endosperm; embryo straight or curved Petals absent Stamens inserted at the bottom of the calyx, erect in bud, opposite the calyx-lobes; anthers 2-celled, opening lengthwise Ovary of 2 connate carpels, 1–2-celled; styles 2, divergent Ovules solitary, pendulous from near the top Leaves alternate, simple, often unequal-sided; stipules paired, caducous Flowers fasciculate, hermaphrodite or unisexual Calyx herbaceous, lobes imbricate, persistent Fruit usually compressed, membranous, dry or thinly fleshy, often winged or appendiculate Seed without endosperm; embryo straight or curved Petals absent Stamens inserted at the bottom of the calyx, erect in bud, opposite the calyx-lobes; anthers 2-celled, opening lengthwise Ovary of 2 connate carpels, 1–2-celled; styles 2, divergent Ovules solitary, pendulous from near the top

Sepals 4–5(8), imbricate or valvate, free or shortly united, persistent Petals absent Trees or shrubs, monoecious or dioecious, sometimes spiny Flowers small, unisexual or bisexual, regular, axillary, solitary or in cymes or clusters Leaves alternate, simple; lamina often unequal-sided at base; stipules lateral, caducous Stamens as many as, and opposite to, the calyx lobes or (not in south tropical Africa) a few more, inserted at the base of the calyx, erect in bud; anthers 2-thecous, opening longitudinally Seeds without endosperm; embryo curved or (not in south tropical Africa) straight Fruit thinly fleshy or compressed, dry and ± winged or appendiculate; endocarp hard Ovary superior, of 2 united carpels, 1(2)-locular; styles 2, divergent; ovule solitary, pendulous from or near apex, anatropous Petals absent Trees or shrubs, monoecious or dioecious, sometimes spiny Flowers small, unisexual or bisexual, regular, axillary, solitary or in cymes or clusters Leaves alternate, simple; lamina often unequal-sided at base; stipules lateral, caducous Stamens as many as, and opposite to, the calyx lobes or (not in south tropical Africa) a few more, inserted at the base of the calyx, erect in bud; anthers 2-thecous, opening longitudinally Seeds without endosperm; embryo curved or (not in south tropical Africa) straight Fruit thinly fleshy or compressed, dry and ± winged or appendiculate; endocarp hard Ovary superior, of 2 united carpels, 1(2)-locular; styles 2, divergent; ovule solitary, pendulous from or near apex, anatropous

Fls regular or nearly so, hypogynous or perigynous, perfect or unisexual; sep (2–)5(–9), distinct or often connate below; pet none, stamens erect in bud, as many as and opposite the cal members, rarely 2 or 3 times as many; ovary superior, bicarpellate, unilocular; ovule solitary, suspended, anatropous or amphitropous; styles 2, stigmatic along the inner side; fr a samara or a small drupe or nut; seeds with dicotyledonous embryo and scanty or no endosperm; woody plants; lvs alternate, simple, distichous, often oblique at base; fls small and inconspicuous, anemophilous, in small cymes or racemes or fascicles, or solitary and axillary. 18/150+.

Trees or shrubs, evergreen or deciduous. Winter buds with scales, rarely naked; axillary buds developed; terminal bud usually dying back early. Stipules usually membranous, caducous. Leaves simple, alternate or rarely opposite, usually distichous, petiolate; leaf blade pinnately veined, basally 3(or 5)-veined, margin entire or serrate. Inflorescences axillary. Flowers monochlamydeous, bisexual, or rarely unisexual or polygamous. Perianth lobes 4-9, imbricate or rarely valvate, persistent or caducous. Stamens usually equal in number to and opposite perianth lobes, opposite, basally adnate to tepals; filaments distinct; anthers 2-celled, longitudinally fissured. Pistil 2-carpellate; ovary superior, 1(or 2)-loculed; ovule 1, suspended, anatropous; integuments 2. Style very short; stigmas 2, linear. Fruit samara, drupes, or winged nutlets, apically usually with persistent stigmas. Endosperm scanty or absent; embryo erect, curved, or involute; cotyledons flat, curved, or flexed. Seedling epigeous.

Fruits either compressed, dry and ± winged or appendiculate, or thinly fleshy Ovary of 2 connate carpels, 1–2-locular; styles 2, divergent; ovule solitary, pendulous from near the top, anatropous Stamens the same number as the calyx-lobes and opposite them or a few more, inserted at the base of the calyx, erect in bud; anthers 2-thecous, opening lengthwise Petals absent Sepals 4–8, free or shortly united, imbricate or valvate, persistent Flowers small, polygamous, solitary or in axillary cymes or clusters Seeds without endosperm; embryo straight or curved Trees or shrubs, sometimes armed Leaves simple, alternate; blade often unequal-sided Stipules lateral, usually free, often small and caducous Ovary of 2 connate carpels, 1–2-locular; styles 2, divergent; ovule solitary, pendulous from near the top, anatropous Stamens the same number as the calyx-lobes and opposite them or a few more, inserted at the base of the calyx, erect in bud; anthers 2-thecous, opening lengthwise Petals absent Sepals 4–8, free or shortly united, imbricate or valvate, persistent Flowers small, polygamous, solitary or in axillary cymes or clusters Seeds without endosperm; embryo straight or curved Trees or shrubs, sometimes armed Leaves simple, alternate; blade often unequal-sided Stipules lateral, usually free, often small and caducous

About 14 genera and 120 species, mostly tropical and north temperate The family is rather poorly represented in Africa, but the species which do occur are mostly widespread across the continent The family is rather poorly represented in Africa, but the species which do occur are mostly widespread across the continent