September 7, 2010

Houseplants Run Amok !

We live in a great climate to grow tropical plants, save for the occasional frosts and windstorms. The down side to this climate is that weeds grow well, too. It gets even more complicated when desirable plants run amok, and become weeds by their aggressive growth. There are many examples of "houseplants gone wild", as there are with many exotic animals that are escaped pets-gone-wild. In a strict definition, a weed is a plant growing out of place, but the definition has no strictures for the value of the plant. A good example is a Royal Poinciana growing in the middle of your brick driveway, causing havoc as it lifts the bricks, and rains leaves everywhere. Everyone who sees a Royal Poinciana agrees it is a gorgeous tree, your driveway ?
Many people move here from out of state, bringing their houseplants with them. When the plants get too large, people plant them outdoors. This is where our story begins............

Juvenile 'Pothos"
Over the last 40 or 50 years, laws have changed to keep up with the increase in weed species, some of which used to be grown as nursery plants for the landscape / interior plant trade. Schefflera, Fishtail Palm, Syngonium Vine, Pothos Vine, Carrotwood Tree, Pongamia Tree, Java Plum and a long list of other plants used to be popular landscape plants, but are now on the hot list of exotic weeds. In controlled environments like shopping malls and commercial landscapes, these plants still make usable trees, but once they escape into the wild natural areas, their desirability diminishes fast. The moral of this story is to be careful what you plant. Watch out for catch-phrases like "fast-growing", "vigorous", " seeds attract birds", and "easily propagated". If you bring houseplants to your new home from up north, leave them in their pots. If you want to plant new plants, consult a few authorities before you do. Weeds are serious problems in almost every state, some of which are escapees from somewhere else.

mature 'Pothos"

In my standard dogma, I suggest you research plants a bit before you plant them. One of the biggest ironies I see is people who want a fast-growing hedge, choose Weeping Fig for the hedge, then complain for years about the costs of trimming it. I never met a hedge that would accept the command "stop growing at six feet, please". A better choice would have been some of the native shrubs like White Indigoberry or Simpson Stopper. Some people plant a lovely patch of Wild Petunia ( Ruellia brittoniana) only to find that it spreads everywhere, and pops up in flower pots 100 feet away. Here at Pinecrest Gardens we have been "managing" the burgeoning populations of pothos, Syngonium, Trema, Leucaena ( Lead Tree), and African Tulip Tree for several years.Many of these were planted as ornamentals decades ago. Melaleuca trees were planted here about 40 years ago, since they were fast-growing and durable trees. We spent a lot of time removing them, since they get out of hand rather fast.

Adult Syngonium podophyllum

Many houseplants have turned into serious weeds, and one in particular, Wood Rose, is commonly brought back from Hawaii as a novelty. It is one of the most aggressive weeds in the state, and similarly for Old World Climbing Fern. Both of these were ornamental species, but both can overcome forests in a hurry. You can get excellent information about weed potentials from the University Extension Office, or from plant societies. Both offer free information, and both are excellent plant information resources.

Be judicious in planting new or little-known plants. You are unlikely to endanger the world by planting a palm or Cassia tree, but be extra careful about bringing home a piece of that beautiful vine you saw at the hotel in Costa Rica, or the groundcover at the airport in Thailand. Some of these plants can grow here at astonishing speed, and your "little introduction" can make a really major impact. If you are skeptical, ask the people who introduced Kudzu Vine, Melaleuca Trees, Asian Cycad Scale, African Giant Snails, Walking Catfish, Green Iguanas, Burmese Pythons, and others into our local environments.

Craig Morell
Pinecrest Gardens

African Tulip Tree-Spathodea campanulata

Lead Tree- Leucaena diversifolia

Wild Petunia-Ruellia brittoniana

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