Coffee, quinine and a red dye all come from one huge plant family
The family that gives us coffee also gave the world quinine, the antimalarial drawn from Cinchona bark, and madder, whose roots dyed cloth red since ancient times. With about 14,200 species, Rubiaceae is the fourth-largest flowering plant family, and some members fling pollen at moths or house ants inside swollen tubers.
Botanists spot Rubiaceae by a tidy set of traits: simple, untoothed leaves in opposite pairs, a stipule bridging the stem between each pair, tubular flowers with fused petals arranged symmetrically, and an ovary set below the flower. Most are shrubs, like coffee, but the family includes trees such as Cinchona, climbing lianas, herbs such as Galium, and even plants that perch on others. Only one species, Pentagonia osapinnata, has compound leaves.
Its roughly 615 genera grow almost everywhere except polar regions and deserts, but diversity peaks in the humid tropics, where woody Rubiaceae shrubs are a major part of rainforest understoreys. Colombia, Venezuela and New Guinea hold the most species; allowing for area, Venezuela leads, followed by Colombia and Cuba. The tribe Rubieae is the exception, centred in temperate lands.
Most species rely on insects, offering nectar from a disc at the base of the flower tube. To avoid self-fertilisation, many present pollen on the outside of the style before the female parts are ready, and in Posoqueria and Molopanthera a catapult launches a ball of pollen onto visiting hawk moths. Others use flowers of different style lengths. Fruits are spread by animals, wind or water; the fruit of Galium aparine hitches rides on fur with hooked bristles.
Partnerships abound. Epiphytes like Myrmecodia grow a tuber from the seedling stem that ants move into. In Pavetta, Psychotria and Sericanthe, Burkholderia bacteria live in dark leaf nodules, probably making toxins that deter grazers. The name comes from Rubia, Pliny the Elder's term for madder, from Latin ruber, red; its roots supplied the dyes alizarin and purpurin. Despite the similar name, blackberries in the genus Rubus belong to the rose family. Antoine Laurent de Jussieu published the family name in 1789, and molecular studies now split it into two subfamilies.
Source: Rubiaceae
