Interspecies Interactions

Young girl holding a tub of vanilla ice cream. [Taken by Jason Ruud.]The most obvious interaction Vanilla planifolia has with another species probably comes as no surprise.  With vanilla ice cream, vanilla cookies, and vanilla, dare I say, everything, this crafty plant has certainly found its way into a considerable wealth of recipes, and into quite a few happy bellies.  As has been noted before, the trip from flower to food is not a simple one.  Vanilla is second only to saffron in price, due to its relative rarity, and strenuous harvest and transformation process.  After the flowers are pollinated, and the pods plucked at their perfect ripeness, the pods are either boiled or frozen, to kill the vegetative tissue, and prevent any further growth.  Next the pods are forced to ‘sweat’ by wrapping the pods in a wool cloth and leaving them out in the sun, which is meant to allow enzymes to catalyze the necessary reactions to give vanilla its distinctive flavor and aroma.  Before this point, neither the Vanilla planifolia flower, nor the ripe pods had that characteristic vanilla smell or taste.  To prevent any rotting, at this point the vanilla pods are left out in the sun during the day to dry out, and kept in airtight boxes during the night.  Any following steps depend on the form the consumer will get their vanilla: pod, powder, or extract. 

An ericoid mycorrhizal fungus isolated from Woollsia pungens.  [Taken by Dr. David Midgley]Humans are certainly not the sole organism Vanilla planifolia interacts with, though!  One of the most fundamental and important relationships vanilla is involved with, is a mutualistic association with fungi in its roots.  Vanilla relies on a fungi in the phylum Glomeromycota, in an association called 'mycorrhizae'.  This relationship provides the fungus with a stable supply and access to the sugars produced by Vanilla planifolia through photosynthesis.  In return, vanilla is able to get water and minerals from the fungus's extensive network of mycelium, allowing it to obtain much more than it could do on its own with its much thicker, shorter roots.  This particular association involves 'endomycorrhizae', fungi whose  hyphae actually enter the plant’s root's cell membrane.  These associations are also referred to as 'arbuscular mycorrhizas' or 'AM's.  This very close contact  allows greater, and easier transfer of materials between the fungi and the plant in which it is associated with.    
Interested in these fascinating fungi?? This website is for you!

Vanilla planifolia vine pictured on a tree.  [Taken by Henrietta Kress,]

Vanilla is also plagued by many annoying pests including many members of the genera: Fusarium, Sclerotium, Phytopthora and Collectroticum, all purveyors of rot. 

And last, but not least, Vanilla relies on its fellow Plantae-members, specifically tropical trees, to get the light for photosynthesis it desperately needs.  The commencial relationship doesn’t harm the trees involved, but allows Vanilla planifolia to climb up its trunk, and have a much better shot at getting some sun, in this very competitive biome. 




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