Bougainvillea
Between 1766 and 1769, Louis-Antoine de Bougainville became the first French navigator to circumnavigate the world. On board was the French naturalist Philibert Commerson, who, during a brief stop in Rio de Janeiro, discovered a plant that has become a horticultural cliché; the garishly-coloured bougainvillea. Bougainville's expedition was notable in many ways, including that Commerson's 'male' assistant turned out to be female; consequently, Jeanne Baret was the first woman to go around the globe. In his undergraduate lectures, in the late-1780s, the Oxford professor John Sibthorp described Commerson as 'a Libertine' but seemed more concerned by Commerson's new genera, which 'he called after the Names of his several Mistresses'. Two decades after the expeditions return, the French botanist Antoine de Jussieu described the genus Bougainvillea in honour of the expedition's commander.
Bougainvillea comprises about 18 species of semi-deciduous Central and South American shrubs or woody vines with thorny stems and persistent, spine-like inflorescence stalks. Three species are grown throughout warm regions of the globe. In the UK, bougainvilleas can be grown outside in the summer but they must be protected from frost in the winter. Bougainvilleas have been adopted as 'official blooms' in parts of east and south east Asia, and are frequently used as cinematic tropes, symbolic of flamboyance and the exotic.
Clusters of inconspicuous, tubular flowers are likely to be pollinated by humming birds, moths or butterflies. The flowers are surrounded by a wreath of colourful, papery, leaf-like bracts. These bracts have attracted horticultural attention since the early nineteenth century, when the genus was brought into European cultivation.
One of the most important hybrids in the history of bougainvillea breeding was discovered by Mrs Butt and named after her, Bougainvillea x buttiana. Mrs Butt's bougainvillea is an accidental garden hybrid between the Brazilian species Bougainvillea glabra and the northern Andean species Bougainvillea peruviana.
Complex hybrids among cultivated species, together with natural mutations and variegation, means accurate naming of bougainvilleas is difficult. However, out of these genetic processes a rainbow of bracts colours has been produced, ranging from reds, oranges and yellows through purples to whites. The distinctive magenta-coloured bracts of some bougainvilleas are because of a class of pigments called betalains, which replace the anthocyanins that are more typical of flowering plants. Betalains are primarily found in a group of related families that make up the plant order Caryophyllales, an order that includes beetroots, cactuses and ice plants.
Further reading
Roy RK and Singh S 2016. Migration and domestication of Bougainvillea: a historical review. Chronica Horticulturae 56: 10-15.
Schiebinger L 2003. Jeanne Baret: the first woman to circumnavigate the globe. Endeavour 27: 22-25.
Stafford HA 1994. Anthocyanins and betalains: evolution of the mutually exclusive pathways. Plant Science 101: 91-98.
Stephen Harris