Vanilla planifolia, the main source of the fragrant spice and flavoring, is a vine in the orchid family. Native to the Neotropics, in the wild vanilla grows from Mexico to Brazil in warm and humid climates and is cultivated on tropical islands in the Indian Ocean such as Madagascar and Réunion. In the Conservatory, you can find it climbing on our cacao tree. Though 'vanilla' as an adjective can indicate something plain and ordinary, the plant itself is anything but.
Vanilla has adapted to a wet and hot environment. Since it often grows as an epiphyte with no roots in the soil, it has little access to water despite growing in tropical climates. Its stems and leaves are succulent to store water. At the same time, the plant's waxy cuticle repels excess rainfall to ensure it does not rot in high humidity. Vanilla is also a CAM photosynthesizer, opening its stomata at night to reduce water loss. Green aerial roots help support the plant as it climbs and can also photosynthesize.
The lovely fragrance of vanilla is due to the organic compound vanillin found in the fruit, the vanilla bean. This scent probably developed as a mechanism for seed dispersal, evolving in tandem with orchid bees. When the fruit is mature, it will crack open, exposing the seeds. Male orchid bees brush their hairy legs along the fruit to pick up the fragrance which helps them attract mates. The seeds stick to the bees and drop off in other locations as they fly.
The expense of vanilla spice is partly because of its peculiar floral anatomy. Though vanilla is self-compatible, it rarely pollinates itself because of the rostellum, a structure that blocks the anthers and stigma from touching. In the wild, vanilla is probably pollinated by various bees. In cultivation, it must be hand pollinated. The rostellum is lifted by a thin tool so that the anthers can be gently pressed down onto the stigma. This technique was developed in 1841 by a 12-year-old slave named Edmond Albius. Though he revolutionized the vanilla industry and his technique is still used today, he died in poverty.
Flowers are only open for one day and are best pollinated in the morning when temperatures are cool. After fruit set, the vanilla beans take up to nine months to mature. Harvest is labor intensive because the fruits do not ripen at the same time and therefore must be checked and picked daily. Vanilla beans must then also be cured, which can take up to another six months. One of the most popular flavors in the world, vanilla is well worth all the effort!