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nasturtium family

Habit Herbs, annual [perennial]; usually glabrous; roots fibrous [tuberous], (producing glucosinolates).
Stems

often trailing [climbing];

not branched.

Leaves

alternate, simple; usually stipules present;

petiole present (often twining);

blade (peltate), margins entire or sinuate.

Inflorescences

axillary, flowers solitary;

bracts absent.

Pedicels

present.

Flowers

zygomorphic;

sepals 5, imbricate, adaxial 1 (or 3) prolonged into slender nectariferous spur;

petals 5 (sometimes fewer by abortion), imbricate, clawed, distal 2 smaller than the others;

stamens 8, (barely exserted) in 2 whorls, unequal;

anthers 2-celled, dehiscence longitudinal;

pistil 1;

ovary 3-carpellate, 3-locular;

placentation axile;

ovule (1 per locule, pendulous from apex), anatropous, bitegmic;

style 1 (apical);

stigmas 3, linear.

Fruits

schizocarps (mericarps), 1-seeded, fleshy or dry.

Seeds

1, (greenish), ovoid;

embryo straight;

endosperm absent.

Tropaeolaceae

Distribution
Mexico; Central America; South America [Introduced in North America; introduced also in Europe, Asia, Africa, Australia]
[BONAP county map]
Discussion

Genus 1, species ca. 90 (1 in the flora).

Tropaeolaceae have sometimes been included in Geraniaceae; they differ in having distinct stamens, fruits that split into 1-seeded mericarps, and persistent stylar beaks. Molecular phylogenies have indicated placement in Brassicales, with which they share the production of glucosinolates. The nearest relative of Tropaeolaceae is, putatively, the Akaniaceae, a family of woody plants in eastern Asia and eastern Australia (L. Watson and M. J. Dallwitz, http://delta-intkey.com, 29 July 2006). The family has been divided into three genera by some (e.g., A. Cronquist 1981): Magallana and Trophaeastrum, both monotypic and restricted to southern South America, and Tropaeolum with the remainder of the species. L. Andersson and S. Andersson (2000), based on molecular sequence data, concluded that the former two genera are imbedded within Tropaeolum, and made the needed transfers so that the family consists now of a single genus.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 165. Author: Gordon C. Tucker.
Parent taxa
Subordinate taxa
Name authority Jussieu ex de Candolle
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