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The families of flowering plants

L. Watson and M.J. Dallwitz

Menyanthaceae Dum.

~ Gentianaceae.

Habit and leaf form. Herbs. With a basal aggregation of leaves. Hydrophytic, or helophytic; when hydrophytic, rooted. Leaves alternate; spiral; petiolate; sheathing; simple, or compound; peltate (sometimes), or not peltate; when compound, ternate. Lamina when simple, entire; pinnately veined, or palmately veined; cross-venulate. Leaves exstipulate; leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral, or bifacial (isobilateral). Hydathodes present. Stomata present; on both surfaces (usually), or mainly confined to one surface (then adaxial, on floating leaves of Nymphoides); anomocytic. The mesophyll with sclerenchymatous idioblasts (in three of the generA), or without sclerenchymatous idioblasts; without crystals.

Axial (stem, wood) anatomy. Nodes tri-lacunar, or penta-lacunar. Primary vascular tissues comprising a ring of bundles; except sometimes in cortical bundles collateral. Internal phloem absent. Cortical bundles present (in Nymphoides and Villarsia, sometimes inversely orientated), or absent. Medullary bundles absent. Secondary thickening absent, or developing from a conventional cambial ring.

The vessel end-walls simple, or scalariform and simple. ‘Included’ phloem absent.

Reproductive type, pollination. Plants hermaphrodite; commonly heterostylous. Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in heads, or in fascicles, or in panicles. The ultimate inflorescence units cymose, or racemose. Inflorescences scapiflorous, or not scapiflorous; fascicles, many flowered cymes, panicles or involucrate heads; with involucral bracts, or without involucral bracts. Flowers small to medium-sized; regular; usually 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present; intrastaminal.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous, or gamosepalous (sometimes connate); regular. Corolla 5; 1 whorled; appendiculate (with interstaminal scales), or not appendiculate; gamopetalous (with a tube); valvate (or induplicate-valvate); regular. Petals often fringed (or crested).

Androecium 5, or 10 (if the scales which sometimes alternate with the stamens are interpreted as staminodes). Androecial members adnate (to the tube); free of one another. Androecium exclusively of fertile stamens, or including staminodes (depending on interpretation of the scales). Staminodes if regarded as such, 5. Stamens 5; inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; isomerous with the perianth; oppositisepalous (the filaments alternating with the C lobes). Anthers sagittate; versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. Anther wall initially with one middle layer, or initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; 3 aperturate (usually), or 6 aperturate; colpate (sometimes parasyncolpate), or colporate, or rugate (exceptionally 6-rugate); 3-celled.

Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium syncarpous; synstylovarious; superior, or partly inferior. Ovary 1 locular. Gynoecium median; stylate. Styles 1 (shortly bifid); apical. Stigmas 2; wet type; papillate; Group III type. Placentation parietal (two placentas). Ovules in the single cavity 10–100 (‘many’); horizontal; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed, or not formed (then the three nuclei degenerating early); when formed, 3; not proliferating; ephemeral to persistent. Synergids pear-shaped. Hypostase present, or absent. Endosperm formation cellular. Embryogeny asterad.

Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry. Capsules septicidal, or loculicidal, or valvular. Fruit 4–100 seeded (‘few to many’). Seeds endospermic. Endosperm oily. Seeds winged, or wingless. Cotyledons 2. Embryo straight.

Physiology, phytochemistry. Inulin recorded. Not cyanogenic. Iridoids detected; ‘Route I’ type (normal and seco). Saponins/sapogenins present, or absent. Proanthocyanidins absent. Ellagic acid absent (Menyanthes).

Geography, cytology. Temperate. Cosmopolitan. X = 9, 17.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Gentianiflorae; Gentianales. Cronquist’s Subclass Asteridae; Solanales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Asterales.

Species 40. Genera 5; Liparophyllum, Menyanthes, Nephrophyllidium, Nymphoides, Villarsia.

Illustrations. • Liparophyllum gunnii: Hooker, Fl. Tasmaniae (1860). • Menyanthes trifoliata (B. Ent.). • Nymphoides peltata (B. Ent.). • Nymphoides peltata (as Limnanthemum nymphoides): Eng. Bot. 921 (1866).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 13th March 2017.’.