The Air Plant

A Plant Hangs On at Zoo Miami – The Air Plant
 By Susana Cortázar

We see them just about anywhere we go.  The park, the street, on trees, on fences, on the ground, and all over Zoo Miami.   What are they?  None other than the ubiquitous air plants in the genus Tillandsia.  And would you believe they belong to the bromeliad family?
Although air plants attach and thrive on hard surfaces such as live oak tree bark, fences and the like, contrary to popular belief they are non-parasitic and get their nutrition and moisture from the air and detritus that accumulates on their leaves and roots, not from the object to which they are attached, thus making them epiphytic plants.  Other epiphytes include mosses, tropical orchids and ferns.
Air plants are most common in arid, forested and the mountainous regions of Central and South America, as well as the southern portion of the United States.
According to Zoo Miami Associate Veterinarian Frank Ridgley, “there are over 500 known species of Tillandsia and approximately six out of the 11 native species can be seen on Zoo Miami grounds.” 

If you’ve been to Zoo Miami, you have probably seen Senior Zookeeper Susan Kong driving her cart, Bobblehead, which is whimsically decorated with various types of air plants.  Although tied to an inanimate object, these air plants will grow and thrive as though they were growing on trees or fences, as their nutrients and moisture are obtained in the same manner as those on tree bark.  “Since they just use the object – in this case the metal cart bars – as an anchor, they should grow just as they would if they were attached to a tree like they are found in nature,” explains Frank.  Susan likes them because they are, “cool-looking, interesting plants which don’t require soil.”  Patrons often stop and ask her what they are and where they can get them, at which point Susan explains this is an endangered species which cannot be harvested, and adds, “the ones I have I did not remove from trees but found them on the ground, so they are ‘rescued’ air plants.”   At one point, Susan even had a lizard and a crab spider living inside on of her plants.
 Susan Kong and her air plants on Bobblehead
When native air plants bloom, they produce large, colorful and intricate flowers, with vibrant red and orange long-stalked flowering stems extending from the center of the plant.  Blooming season is from mid-winter through mid-summer.
Of course, like all nature, air plants are subject to threats such as weevils, humans, draughts, and habitat destruction, which have resulted in a decline in their numbers – thus their endangered status   And as if these threats weren’t enough, a new one has reared its ugly head!  As Frank the vet, and obviously a plant connoisseur as well, explains, “the non-native Mexican bromeliad weevil (Metamasius callizona) has been introduced into Florida and has caused significant mortality in many of the native species.  The adult weevil will feed on the leaves of the plants, lay its eggs on the leaves, and the larvae cause significant damage to the leaves and attachment of the plant base to its roots.  This ultimately results in the plant’s death.”
Weevils get nutrients from the air plants and also use them as a safe place for their larvae to grow.  “However,” says Frank, “there is the potential that the native species that the weevils chooses as a replacement for its natural plant host will not be able to survive the weevil’s damage.  Sometimes these non-native animals do not have natural predators or diseases to keep their population numbers in balance and they can then overwhelm the native species when their population grows uncontrollably.”
At Zoo Miami, you will only find the air plants on the live oak trees, since those are the trees these plants arrived on and they provide a rough bark the air plant’s roots can firmly latch on to.  Because of the way the zoo is landscaped, it would be difficult for one air plant to jump to another unless purposely transplanted to a tree other than a live oak.  A plus regarding the live oak tree is that since it is extremely sturdy, it can sustain hurricane winds, affording the air plant relative safety during storms.
Air plants are slow growers and when they flower, the parent plant will die.  As far as their lifespan, numerous factors come into play – genetics, sunlight, rain, and other environmental conditions. 
Sadly, as most of the native Tillandsia species are either listed as threatened or endangered, it is illegal for anyone to possess one without the correct permit.  Removing one from a natural area is also illegal, so don’t even think about it!  There are some exotic imported species that can be bought, but please make sure they don’t spread into the environment.  Keep them indoors and far from natural areas to prevent disease and competition with other plants.
So should you come across an air plant, no matter how beautiful you think it will look in your backyard, please do the right thing and place it on the tree from which it fell or put it on another nearby tree, fence or sturdy-enough surface where it can latch on to and survive.  Let’s do our part in conserving these beautiful and unique plants.  As Susan says, “If somebody finds an air plant on the ground, please wedge it into the cracks of a tree where it can continue its happy life.”