Life History & Reproduction
Growing vanilla is very labor intensive, and it can take up to 5 years for a vine to mature and produce vanilla pods. After being planted and reaching the third year of growth, the Vanilla planifolia vine flowers. The full vine will flower over the course of about 2 months. Each flower is open for 24 hours, but must be pollinated within 8-12 hours, or else the flower wilts, drops from the vine, and no pods can be produced. However, the means by which pollination happens is not as simple as it may seem.
For a very long time, Mexico was the sole grower of Vanilla planifolia, because vanilla had no natural pollinators elsewhere in the world. Attempts were made to introduce the plants to other locations with similar climates and environments, but without that specific pollinator all attempts were, as you could say, “fruitless.” The flowers bloomed, but no vanilla pods were produced. Much later, it was later found to be pollinated chiefly by a small bee called the Melipona bee, and also hummingbirds.
Vanilla planifolia is hermaphroditic
(containing both male and female parts) and the flower itself is
self-fertile, but incapable of self pollination.
Vanilla’s pollen is also largely inaccessible to most
pollinating insects. It
requires outside action to either transfer pollen from an anther to
the stigma, or lift the thin-membrane preventing self-fertilization,
or rostellum, and press the flower's anther to the stigma.
Vanilla planifolia, and many other species of flowering
plants require double fertilization to fruit, an adaptation that
allows the flower to concentrate its energy on producing seeds that
have the best chance at growth and survival.
If the flower is cross pollinated, as often done by insects,
the seeds are viable, and can produce further generations of viable
offspring. If the flower
is self-pollinated, however, it produces only sterile seeds.
The biggest advancement in vanilla growth and pollination happened in 1841, through a discovery by Edmond Albius, a slave on the island of Réunion. Albius discovered the way by which the rostellum could be lifted out of the way using a small stick or blade of grass, so that the pollen could be manually passed from the anther to the stigma. Now practically all vanilla is produced by hand pollination. (To see how, click here.)
When the flower is pollinated, a pod will grow 6-10 inches in 6 weeks. A healthy vine produces about 100 pods per year, each with thousands of tiny black seeds, but if too many flowers are pollinated the vine may be overloaded and can die. Most of the vanilla fragrance resides in the seeds and the oily liquid surrounding those seed. Crystallized vanillin can be seen in vanilla pods of exceptionally good quality forming tiny white needles, called ‘givre’, French for ‘frost’, on the surface of the pods.
For more information on Vanilla planifolia reproduction, and the importance of the Melipona bee, check out this video by Exploration Films.