Oxalis massoniana is a clump-forming perennial with hairy stems, narrow leaves and bright orange flowers; it is named after the Scottish botanist Francis Masson.
About this species
Oxalis massoniana is rare in the wild. It is known only from Van Rhyns Pass, South Africa, a barren rocky mountain plateau where sandstone rocks emerge from evergreen scrub. It was cultivated in New Zealand and from there, in 2000, introduced into cultivation in England. About 500 Oxalis species are found throughout the tropical and temperate regions of the world, but it is in South Africa where the genus has undergone particularly rapid speciation (in both speed and number). There are about 200 species of Oxalis in South Africa, of which around 120 species occur in the Cape region (making Oxalis the seventh largest genus there). About 80% of Oxalis species in the Cape are endemics (found only there and nowhere else).
Geography & Distribution
Native to South Africa, in the Northern Cape, on Van Rhyns Pass, south-west of Nieuwoudtville.
Oxalis massoniana (Image: Richard Wilford)
A winter-growing, dwarf, bulbous perennial, usually clump-forming. The stems are simple, up to 40 mm high, upright, hairy and usually reddish. The leaves are mostly unstalked, with three narrow leaflets about 5 mm long and 1.2 mm wide, with a two-lobed apex. The trumpet-shaped flowers are 16–18 mm long, opening in the sun, with five shiny orange petals and a yellow throat. Each flower has ten stamens, five of which are short and five long, and five styles, which are shorter than the stamens and are recurved, with many-branched stigmas (at least in the cultivated clone). The fruit is a spherical capsule.
Illustration from Curtis's Botanical Magazine
Colour print of Oxalis massoniana after a watercolour by Christabel King (2009), taken from Curtis's Botanical Magazine (Image: Christabel King)
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About Francis Masson
Oxalis massoniana is named after Francis Masson, a Scottish student gardener at Kew who was sent to the Cape by Sir Joseph Banks in 1772 to collect seeds and plants for the Royal Botanic Gardens, Kew. Masson’s first visit lasted from 1772 to 1775, and while there he met and travelled with Carl Thunberg, a student of the Swedish botanist Carl Linnaeus. Masson himself became a competent botanist, as well as a successful plant collector, and wrote and illustrated a book on stapeliads (succulents belonging to the Apocynaceae plant family). Masson travelled widely in the Cape over a period of 12 years, making large collections which he sent back to Kew, and is known to have visited the Nieuwoudtville area in late 1774.
Oxalis massoniana is cultivated as an ornamental, and is grown in pots or planted in rock gardens.
Although there are no known hazards for O. massoniana, other species of Oxalis contain oxalic acid and are potentially poisonous to humans and livestock if consumed in large quantities. The name Oxalis, comes from the Greek oxis, which means acid, referring to the sour-tasting sap of some species.
Oxalis massoniana grows well in a small pot of rich clay soil. It should be watered in the autumn and winter, but kept dry during the summer.
This species at Kew
Oxalis massoniana can be seen in the Davies Alpine House at Kew.
Pressed and dried specimens of Massonia depressa are held in Kew’s Herbarium, where they are available to researchers from around the world, by appointment. The details of some of these, including images, can be seen on-line in the Herbarium Catalogue.
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