Neotropical Tropaeolaceae

Description

Herbaceous climbers often with tuberous roots; plants dioecious.  Leaves simple, alternate, estipulate, entire and often peltate or deeply lobed, to palmate. Inflorescence axillary, few-flowered or flowers solitary. Flowers showy, colourful, hermaphrodite, usually zygomorphic, sepals 5, united forming a spur or calcar; petals 5, clawed, 3 lowermost frequently variously marked towards center of flower; stamens 8, in 4 pairs opposite and alternate with petals, free, anthers 2-locular; ovary superior, 3-carpelate, 3-locular, placentation axile, uni-ovulate, 1 style. Fruits fleshy schizocarp, splitting into 3 one-seeded fruticules, or fruit 3-winged; seeds rounded.

Notes on delimitation

• The Tropaeolaceae is a family related to the Brassicales (Brassicaceae and Caricaceae), where it was placed due to morphological (stamen number and disposition) and chemical characteristics. Its phylogenetic relationships were confirmed by recent molecular studies (APG II, 2003, Souza & Lorenzi 2005).

Distribution in the Neotropics

• The Tropaeolaceae is a small family (2 genera, 100+ species) all endemic to the Neotropics.

Distinguishing characters (always present)

• Herbaceous climbers with entire to palmate leaves.
• Flowers axillary, showy, generally solitary, with noticeable spur.
• Flowers zygomorphic with 8 stamens.
• Ovary 3-locular, each locule uni-ovulate.

Other important characters

• Leaves often peltate, plants usually arising from tuberous roots.
• Fruit fleshy, splitting into 3 fruticules, or 3-winged (Magallana).

Key differences from similar families

• It differs from the Brassicaceae (Capparaceae) in its herbaceous, climbing habit, and the calcarate flowers.

Number of genera

• 1. Tropaeolum L. - around 100+ species distributed mostly in Andean countries and in the highlands of other regions.
• 2. Magallana Cav.  - 1-2 species, Southern South America.
• 3. Tropaeastrum - 1 species, Patagonia.

Status

• Endemic to the Neotropics, more often in the highlands, with one species cultivated and becoming widely naturalized in Brazil (Tropaeolum majus L.).

General notes

• Tropaeolum majus L. is edible; its fruit and flowers taste like capers and are used to garnish salads.

Important literature

APG II, 2003. An update of the Angiosperm Phylogeny group classification for the orders and families of flowering plants: APG II. Bot. J. Linn. Soc. 141(4): 399-436.

Souza, V.C. & Lorenzi, H. 2005. Botânica Sistemática: guia ilustrativo para identificação das famílias de Angiospermas da flora brasileira, baseado em APG II. Nova Odessa, Brazil: Instituto Plantarum.

How to cite

Zappi, D. (2009). Neotropical Tropaeolaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Tropaeolaceae.htm.