Tuesday, January 5, 2016

American Holly

American Holly with berries 

     American Holly (Ilex opaca) is what most people envision when they think of a holly. Despite there being several deciduous hollies, this evergreen tree is what typifies the holly to most people. This is specially true during the holidays, as this evergreen, along with its evergreen relatives from the Old World, were often a large part of the holiday festivities. Indeed another common name for this tree is "Christmas Holly." Each individual leaf may last 3 years before dropping off and getting replaced on a living tree, and the leaves cling on long after a branch is cut, making this plant ideal for decorations.
     This small tree (to 50' or so) was heavily collected as part of holiday decorations. Being slow growing, this led to great shortages and threatened its existence until protections were enacted to preserve them. The dense crown of evergreen, spiky leaves and pyramidal growth made this a holiday favorite. Though not as shiny as its European cousin ("opaca" in its scientific name means "not shiny"), it was a staple of many households. It, along with its relatives, remains a favorite of landscaping, with 1000 types of Ilex in cultivation. We have 13 native holly species in the East and American Holly is the state tree of Delaware.
     This tradition of using the evergreen hollies dates back well before Christmas and Christian tradition. The Romans for example used hollies as part of their Saturnalia or winter solstice celebrations. It was then adopted by Christians and others as a symbolic gesture of green life in midwinter. It was traditionally considered bad luck to bring hollies indoors before Christmas or to leave them up after Epiphany or Three Kings Day (January 6th).
     There are problems with being an evergreen tree in winter however. Not only must you produce anti-freezing agents in your leaves, but the leaves need a waxy covering to keep from losing water too quickly. Available water is hard to find in winter and the plant can ill-afford to lose any through its leaves. But these green leaves are tempting to herbivores as well, and so the spines on the leaves. As if that wasn't enough, snow and ice can be heavy and break limbs. The leaves thus point downwards to shed snow and are very flexible to withstand what they cannot shed. All good adaptations for an evergreen tree.

Downward pointing leaves help American Holly shed heavy snow.

     If considering hollies for the garden, it is good to keep in mind that most of these trees are dioecious, meaning that male and female flowers are formed on separate trees. If you plant a male tree, you will never get berries (drupes botanically). If you plant a female and there are no male trees nearby, you also will not get fruit.
     The colorful berries on American Holly are not edible to people, but at least 49 bird species have been documented eating them. They are however not usually the first choice or preferred food. It may be because they have a low fat content and so are not as nutritious, but I think they simply are not tasty to most birds. That is one reason they hang on the trees for so long (and add holiday color). After being conditioned by the cold, and when there are few remaining food sources, is when they are finally eaten by birds. Having said that, they can be real life savers, with flocks often descending on them in late February and March in many cases and completely stripping the trees bare. Occasionally a mockingbird will guard its tree from all other bird intruders through the winter. Though it is sometimes considered a "starvation food" by some, it is an important food source. Check out this short video showing American Robins feeding on American Holly:

     Each berry (technically a drupe) contains 4 brown nutlets that are dispersed mostly by birds. It may take 10 years for a tree to mature enough to produce fruits. Each individual tree can live to 150 years or so if lucky. The smooth, thin bark however makes it susceptible to fire damage. It also is a favorite target for sapsuckers to drill into, leaving long rows of holes. These then are often the target of hornets who strip off pieces where its been damaged to use in constructing their own paper nests. All this damage may result in girdling the tree to death.

The smooth grey bark of this American Holly has been marred by numerous sapsucker drills.

     Some other animals also make use of holly. Thirty-nine caterpillar species (5 of which are not native) have been noted as using the tree as a food source. This includes the Henry's Elfin butterfly and the Holly Azure butterfly, who's caterpillars feeds on its flowers. A couple of leaf miner flies also feed within the leaves, leaving distinctive trails where they've fed.

A Holly Leaf Miner Fly has left its feeding trails within the leaf itself.

     Several species of pollinators visit the flowers to feed, though ants in particular are attracted to them. They do not act as pollinators however, rather they just steal the nectar for themselves.

Ants robbing American Holly flowers of their nectar.

     People have been using hollies for more than just decoration and holiday cheer however for a long time. American Holly use was documented by the great ethnobotanist Daniel Moerman by several Native American Indian tribes for example. The Alabama used the bark for an eye wash, as did the Choctaw. The Catawba used an infusion from the leaves for sores and for sore muscles. The Koasati made an infusion from the bark that could be rubbed into the skin for itching. It was the Cherokee that had the most uses for American Holly however. They chewed the berries (which can be toxic) for colic, to treat acid reflux and other gastrointestinal issues, and for hernias. They made a dye from the fruit and used the white wood (the tree is still sometimes referred to as White Holly) in carving spoons. When all else failed, they used the spiky leaves to scratch cramped muscles.
     During the Civil War, Confederate doctor Francis Porcher was ordered to find alternatives for goods no longer available due to Northern blockades. He noted that American Holly bark could be used for colds, coughs, and tuberculosis. The berries he said could be used as an emetic to induce vomiting. An infusion of the leaves could be used as a diaphoretic, to induce sweating that would treat small pox, lung issues, and conditions of the throat. He suggested that the inner bark could be a substitute for quinine and be used to treat fevers. A tea made from the roots could also treat colds, coughs, and stimulate appetite. Consuming the berries could be used to expel intestinal worms. The inner bark he reported could be used to create "bird lime" sticky enough to capture birds. Porcher also mentioned that the light colored wood could take dyes easily and be used for carpentry.
     The wood is sometimes still dyed and used as a substitute for ebony in making black piano keys. Folk healers sometimes still brew tea from the leaves that is said to induce sweating and alleviate fevers. This tea reportedly has caffeine. In the language of flowers (sometimes called floriography) holly is supposed to signify foresight. In ancient times, holly was said to contain magical powers. The flowers could turn water to ice it was said, while planting the tree by a building would lend protection from lightning and witch craft.
     I like to pick a leaf off the ground and hold it on opposite sides by the spines. I then blow on it, making it twirl between my fingers in a helicopter fashion. This small trick is a favorite of young kids when I wrap up a nature walk. American Holly has such a rich heritage of uses and folklore. It is nice to celebrate this native tree any time of year, making any of them Holly-days.

Holding a holly leaf between your fingers and blowing on the underside of the leaf produces a whirlybird.

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