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Epiphytes & Parasites

The much-maligned ball moss, Tillandsia recurvata, is actually a bromeliad, related to pineapples and the brilliantly-flowered exotics seen in greenhouses. Bromeliads can be terrestrial, saxicolous or epiphytic. Terrestrial species grow, like most plants, with their roots in the soil. Saxicolous ones grow on rocks and epiphytes grow on other plants.

Epiphytes are not parasites; none draw any nutrients directly from their hosts. The advantage bromeliads gain from their arboreal perch is height. They are elevated beyond the reach of most browsing animals and receive more sunlight for photosynthesis than they would if growing on the ground in a tropical forest.

Why is it, then, that ball moss is thought by many to be a scourge worse than mistletoe? Primarily because of a misunderstanding regarding how trees grow and eventually lose their lower branches. Look closely at the trunk of any large tree and you will notice circular patterns in the bark with indicate the positions of long-dead branches. Throughout its life, a tree is forming new branches at its growing points and killing its lower ones. Branching occurs to disperse, both efficiently and uniformly, the sunlight-catching leaves throughout the canopy of a tree. 

Limbs die naturally when their leaves cease to produce enough nutrients because shading has impaired their ability to photosynthesize. At any time, a mature tree can be expected to have several limbs in the interior of its canopy in various stages of decline, and others dead and decaying. In the absence of ball moss, such a scene does not beg for fantastic explanations.

Now comes the innocent ball moss seed, propelled by wind away from the flower spike where it formed. Most seeds land on inhospitable sites, never to grow. A very few become tangled in the bark crevices of a limb somewhere within a tree's canopy. In such a site, protected from too much sunlight, they germinate and grow to maturity if rainfall and atmospheric humidity are sufficient. The ball moss will thrive until the branch supporting it falls due to death and decay.

In general, ball moss grows best in the interior of trees where it is shielded from the sun's drying rays. In sites where relative humidity is ample, ball mass can spread to the upper reaches of a tree and even onto electrical wires or fences. This phenomenon can be seen near Pleasanton and in some of the narrow river valleys in the Hill Country.

There are still those who assert the contrary position, claiming ball moss is detrimental to trees.  Another answer to those skeptics is to point to large, old trees, whose dying, interior branches are fully clothed with ball moss and then inquire how such a tree, a paragon of its species, could ever have achieved its lofty status having spent the last 200 years "encumbered" by that native epiphyte? 

If one wished to proceed further with such a line of reasoning, one might also inquire of the skeptics how it happened that any tree was able to live to maturity before this area was civilized and its woods "freed" from the "ravages" of ball moss? Will they answer that the aboriginal Americans spent their days as compulsive arborists busily plucking every single clump of ball moss?

If your trees are healthy and actively-growing and you cannot stand the sight of ball moss, just prune out the inner dead wood. Chemical sprays are used by some to kill ball moss, but because of its tenacious roots, it will remain, dead and very ugly, on the tree for up to three years until it decays.

If your trees are declining and have more ball moss than your neighbor's trees, pay an arborist or horticultural consultant to determine the real cause of their malaise. Just removing ball moss from sick trees will not cure the underlying problem.

Some "arborists" will still attempt to persuade you to spend large sums to remove ball moss. They do so for personal pecuniary advantage and not for the benefit of your trees.

The botanical images on this site were produced by The Photon Hunt.

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Copyright at Common Law by Manuel Flores