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The families of flowering plants

L. Watson and M. J. Dallwitz

Tropaeolaceae DC.

Including Cardamindeae (Cardamindaceae) Link

Habit and leaf form. Herbs (with mustard oils and watery juice); not resinous. Plants somewhat succulent, or non-succulent. Annual to perennial; without conspicuous aggregations of leaves; when perennial, tuberous. Prostrate or climbing; often petiole twiners, or scrambling. Leaves alternate, or alternate and opposite (sometimes opposite below); flat; petiolate (the petioles often long and twining); non-sheathing; gland-dotted, or not gland-dotted; simple, or compound; peltate; when compound, palmate. Lamina when simple entire, or dissected; when simple/dissected, palmatifid; palmately veined; cross-venulate. Leaves stipulate, or exstipulate; leaf development not ‘graminaceous’.

Leaf anatomy. Mucilaginous epidermis present, or absent. Stomata present; mainly confined to one surface, or on both surfaces; anomocytic. Minor leaf veins without phloem transfer cells (Tropaeolum).

Axial (stem, wood) anatomy. Cork cambium present, or absent; initially deep-seated. Nodes tri-lacunar. Primary vascular tissues comprising a ring of bundles, or in a cylinder, without separate bundles to comprising a ring of bundles (the separate bundles becoming joined via an interfascicular cambium); collateral. Secondary thickening absent, or developing from a conventional cambial ring (the interfascicular cambium sometimes producing phloem to the outside, as well as prosenchymatous elements to the inside).

The vessel end-walls simple. The vessels without vestured pits.

Reproductive type, pollination. Plants hermaphrodite. Pollination entomophilous; mechanism conspicuously specialized (in T. majus, the the anthers move sequentially to the nectariferous spur to shed their pollen before returning to their original positions, when the style moves to the spur. The hairs on the lower margins of the anterior petals exclude the entry of insects too small to effect pollination).

Inflorescence, floral, fruit and seed morphology. Flowers solitary; axillary; medium-sized (showy); very irregular (usually), or somewhat irregular (Tropaeastrum); zygomorphic. The floral irregularity involving the perianth and involving the androecium. Flowers cyclic; pentacyclic. Free hypanthium present (the corolla slightly perigynous).

Perianth with distinct calyx and corolla; 7–10; 2 whorled; isomerous, or anisomerous (the corolla sometimes incomplete); petaloid. Calyx 5 (the sepals petaloid); 1 whorled; gamosepalous; 5 blunt-lobed; bilabiate; long to short spurred (from below the dorsal (adaxial) sepal(s)); imbricate, or valvate; with the median member posterior. Corolla 2–5 (the two upper members exterior and often differing from the lower, which are sometimes missing); 1 whorled; polypetalous; imbricate. Petals clawed; variously lobed or fringed.

Androecium 8. Androecial members free of the perianth; markedly unequal (declinate); free of one another; 2 whorled (four per whorl, the median of each supposedly suppressed). Androecium exclusively of fertile stamens. Stamens 8; filantherous (the filaments filiform). Anthers basifixed; dehiscing via longitudinal slits; latrorse; tetrasporangiate. Pollen grains aperturate; 2–3 aperturate; colporate (the colpi short); 2-celled.

Gynoecium 3 carpelled; partly petaloid (sometimes with petaloid modification of style and/or stigma), or non-petaloid. Carpels reduced in number relative to the perianth to increased in number relative to the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 3 locular. Gynoecium oblique; stylate. Styles 1; apical. Stigmas 1, or 3; 3 lobed; dry type; non-papillate. Placentation axile to apical. Ovules 1 per locule; pendulous; epitropous; with ventral raphe; non-arillate; anatropous; bitegmic; tenuinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Endosperm formation nuclear. Embryogeny solanad.

Fruit fleshy (sometimes), or non-fleshy; a schizocarp. Mericarps 1 (Magallana), or 3; comprising nutlets, or comprising drupelets, or samaroid (Magallana). Dispersal unit the mericarp. Seeds non-endospermic; with amyloid. Embryo well differentiated. Cotyledons 2; thick, plano-convex. Embryo chlorophyllous (Tropaeolum majus); straight.

Seedling. Germination cryptocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Tropaeolum. Mustard-oils present (in the leaves, stems and roots, seemingly not always in special cells). Not cyanogenic. Arbutin absent. Iridoids not detected. Proanthocyanidins absent. Flavonols present; kaempferol and quercetin. Ellagic acid absent.

Geography, cytology. Neotropical. Temperate to tropical. Mexico to temperate South America, widely introduced elsewhere. X = 12–14.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rutiflorae; Tropaeolales. Cronquist’s Subclass Rosidae; Geraniales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Brassicales.

Species 92. Genera 3; Magallana, Tropaeastrum, Tropaeolum.

Illustrations. • Technical details: Tropaeolum. • Technical details: ‘Chymocarpus’, Tropaeolum (Lindley). • Tropaeolum azureum: Bot. Reg. 65, 1842. • Tropaeolum brachyceras: Bot. Reg. 1926, 1837. • Tropaeolum majus: Bot. Mag. 17, 1786. • Tropaeolum minus: Bot. Mag. 98, 1789. • Tropaeolum tricolorum: as T. tricolor, Bot. Reg. 1935, 1837.

The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. This is much more easily achieved using 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).

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 22nd August 2016.’.