The Vanilla Orchid
The main species harvested for vanilla is V. planifolia. Although it is native to Mexico, it is now widely grown throughout the tropics. Indonesia and Madagascar are the world's largest producers. Additional sources include V. pompona and V. tahitiensis (grown in Niue and Tahiti), although the vanillin content of these species is much less than V. planifolia.
Vanilla grows as a vine, climbing up an existing tree (also called a tutor), pole, or other support. It can be grown in a wood (on trees), in a plantation (on trees or poles), or in a "shader", in increasing orders of productivity. Its growth environment is referred to as its terroir, and includes not only the adjacent plants, but also the climate, geography, and local geology. Left alone, it will grow as high as possible on the support, with few flowers. Every year, growers fold the higher parts of the plant downward so the plant stays at heights accessible by a standing human. This also greatly stimulates flowering.
The distinctively flavored compounds are found in the fruit, which results from the pollination of the flower. These seed pods are roughly a third of an inch by six inches, and brownish red to black when ripe. Inside of these pods is an oily liquid full of tiny seeds. One flower produces one fruit. V. planifolia flowers are hermaphroditic: they carry both male (anther) and female (stigma) organs. However, self-pollination is blocked by a membrane which separates those organs. The flowers can be naturally pollinated by bees of genus Melipona (abeja de monte or mountain bee), by bee genus Eulaema, or by hummingbirds. The Melipona bee provided Mexico with a 300-year-long advantage on vanilla production from the time it was first discovered by Europeans. The first vanilla orchid to flower in Europe was in the London collection of the Honourable Charles Greville in 1806. Cuttings from that plant went to Netherlands and Paris, from which the French first transplanted the vines to their overseas colonies. The vines grew, but would not fruit outside Mexico. Growers tried to bring this bee into other growing locales, to no avail. The only way to produce fruits without the bees is artificial pollination. Today, even in Mexico, hand pollination is used extensively.
In 1836, botanist Charles François Antoine Morren was drinking coffee on a patio in Papantla (in Veracruz, Mexico) and noticed black bees flying around the vanilla flowers next to his table. He watched their actions closely as they would land and work their way under a flap inside the flower, transferring pollen in the process. Within hours, the flowers closed and several days later, Morren noticed vanilla pods beginning to form. Morren immediately began experimenting with hand pollination. A few years later in 1841, a simple and efficient artificial hand-pollination method was developed by a 12-year-old slave named Edmond Albius on Réunion, a method still used today. Using a beveled sliver of bamboo, an agricultural worker lifts the membrane separating the anther and the stigma, then, using the thumb, transfers the pollinia from the anther to the stigma. The flower, self-pollinated, will then produce a fruit. The vanilla flower lasts about one day, sometimes less, so growers have to inspect their plantations every day for open flowers, a labor-intensive task.
The fruit, a seed capsule, if left on the plant, ripens and opens at the end; as it dries, the phenolic compounds crystallize, giving the fruits a diamond-dusted appearance, which the French call givre (hoarfrost). It then releases the distinctive vanilla smell. The fruit contains tiny, black seeds. In dishes prepared with whole natural vanilla, these seeds are recognizable as black specks. Both the pod and the seeds are used in cooking.
Like other orchids' seeds, vanilla seeds will not germinate without the presence of certain mycorrhizal fungi. Instead, growers reproduce the plant by cutting: they remove sections of the vine with six or more leaf nodes, a root opposite each leaf. The two lower leaves are removed, and this area is buried in loose soil at the base of a support. The remaining upper roots cling to the support, and often grow down into the soil. Growth is rapid under good conditions.
Flowering normally occurs every spring, and without pollination, the blossom wilts and falls, and no vanilla bean can grow. Each flower must be hand-pollinated within 12 hours of opening. In the wild, very few natural pollinators exist, with most pollination thought to be carried out by the shiny green Euglossa viridissima, some Eulaema spp. and other species of the euglossine or orchid bees, Euglossini, though direct evidence is lacking. Closely related Vanilla species are known to be pollinated by the euglossine bees. The previously suggested pollination by stingless bees of the genus Melipona is thought to be improbable, as they are too small to be effective and have never been observed carrying Vanilla pollen or pollinating other orchids, though they do visit the flowers. These pollinators do not exist outside the orchid's home range, and even within that range, vanilla orchids have only a 1% chance of successful pollination. As a result, all vanilla grown today is pollinated by hand. A small splinter of wood or a grass stem is used to lift the rostellum or move the flap upward, so the overhanging anther can be pressed against the stigma and self-pollinate the vine. Generally, one flower per raceme opens per day, so the raceme may be in flower for over 20 days. A healthy vine should produce about 50 to 100 beans per year, but growers are careful to pollinate only five or six flowers from the 20 on each raceme. The first flowers that open per vine should be pollinated, so the beans are similar in age. These agronomic practices facilitate harvest and increases bean quality. The fruits require five to six weeks to develop, but around six months to mature. Over-pollination results in diseases and inferior bean quality. A vine remains productive between 12 and 14 years.
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