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Tropaeolaceae Juss. ex DC., nom. cons.
the nasturtium family
The name of Tropaeolum, the only genus in the family, is derived from the Latin word tropæum, a trophy, referring to the shape of the flowers. Most species are climbing or trailing herbs with more-or-less succulent stems and leaves, the latter being alternate and peltate. The flowers are solitary on long axillary peduncles. There are 5 sepals, one produced into a long slender nectar-spur. There are 5 petals, clawed, often cut or fringed, the upper two different from the others. There are 8 stamens, and a trilocular ovary, each cell with one ovule. The fruit consists of three one-seeded carpels. The pollination mechanism is highly specialized. In T. majus, for example, the anthers move sequentially to the nectariferous spur to shed their pollen, before returning to their original position, when the style moves to the spur. The hairs on the lower margins of the anterior petals prevent the entry of insects that are too small to effect pollination.
Tropaeolum majus - Nasturtium
Photograph © Donald Simpson 2014
Page last updated 30th March 2018