Whether it's a Hoboken brownstone with just ten square feet of front yard or a sprawling 50-unit complex nestled in the Watchung hills, no condo association is complete without at least a little bit of colorful landscaping. Plants and flowers not only contribute to the lush aesthetic of a property, but also have a emotionally calming effect.

Along with all the benefits, however, are risks—many plants can pose a danger to children, pets and other wildlife. Certain types of plants are extremely toxic, and can cause symptoms ranging from nausea and diarrhea to seizures, convulsions, depression of the central nervous system, and even death in some cases. More alarming still, some of the most toxic plants are also the most common. Therefore, it's important for boards, residents, and property managers to be aware and work with their individual landscaping professionals to make sure that the plants that look so pretty in HOA flowerbeds and planters are safe and non-toxic.

Pretty but Poisonous

According to information provided by the Children's Hospital of Pittsburgh, plants rank fourth on the list of most common ways people get exposed to poisons, following medications, household cleaning products, and health and beauty aids. While symptoms resulting from minimal exposure to poisonous plants are typically mild—usually limited to nausea or itchy skin rashes and hives—prolonged exposure or ingestion of larger quantities of toxic plants or flowers can cause fatal malfunctions of the heart, liver, kidneys, and other organs.

A few common plants that can be harmful to humans include azaleas, elephant ear, holly, lily-of-the-valley, mistletoe, morning glory, nightshade, oleander, philodendron, rhododendron, yew, and of course poison ivy, poison oak and poison sumac.

The fact that the leaves of English ivy can be fatal if swallowed is not reason enough to stop planting the vine altogether, of course. People don't tend to eat ivy leaves—just as people don't generally go around eating mistletoe berries, azalea petals, or whole rhododendron plants. Those who may harbor such an inclination are usually small children, and with a few precautions, kids can usually be kept away from potentially dangerous plants.

Pets, however, are another story. While most animals know instinctively what to avoid, there are those who will consume anything and everything. Animals can also be difficult to contain, especially if they're left home alone all day or are allowed the run of a yard or other outdoor enclosure. The list of potentially dangerous plants expands a bit when animals are considered.

According to the American Society for the Prevention of Cruelty to Animals (ASPCA) the most common poisonous plants are:

Sago Palm:The seeds of this plant look like nuts, but can cause vomiting and diarrhea in milder cases, and liver failure in extreme cases.

Lilies:No one knows exactly why, but when cats eat lilies, cats die. Melissa Marshall, DVM, a critical care veterinarian with Red Bank Veterinary Hospital in Tinton Falls, says, "Lily toxicity in cats is the number one poison that we see."

Tulips:Not the petals but the bulbs of these beautiful plants contain potent toxins that can harm a pet's central nervous system. So be careful during the planting season, and don't leave tulip bulbs sitting around on windowsills or stoops.

Azalea/Rhododendron:The nectar in the flowers of type of plant is laden with poisons called grayanotoxins, which are as harmful as they sound. Mild exposure causes temporary effects such as nausea, vomiting, dizziness, and irregular heartbeat, but severe exposure can be fatal.

Oleander: The entire plant is poisonous, and ingestion has deleterious effects on a pet's digestive system and heart function.

Castor Bean:A common houseplant sold at grocery stores. Contains a potent poison called ricin, which causes severe abdominal pain if consumed.

Cyclamen:Also a common plant at grocery stores. The root of the plant is the root of the poison.

Kalanchoe: Not as pathogenic as other plants, but contains toxins that can impair cardiac rhythm.

Yew:Contains an active toxin called taxine that can be fatal to pets. The Japanese variety is common in New Jersey.

Dr. Marshall cites other potentially poisonous plants that are endemic to the region, including water hemlock, narcissus bulbs, buttercups, and oak. "Acorns, if consumed in large enough quantities, can also be poisonous," she says.

In addition to the most common varieties of plants, there are seasonal ones, too, that can be harmful or fatal to pets and even to humans if consumed.

"The Holly and The Ivy" may be celebrated in Yuletide song, but both contain powerful poisons. Kissing under the mistletoe won't bring on any ill effects (unless the person you're kissing has a cold), but eating its berries certainly will. Children are also drawn to the plants' bright-colored berries and glossy leaves. For this reason, scientists at Kansas State University suggest barring holly, ivy and mistletoe—as well as azalea and Jerusalem cherry—from places where small children or pets might access them.

David Paulovic of Kale's Nursery & Landscape Service in Princeton agrees. "The bark of cherry trees is highly toxic," he says. "That's where cyanide was originally derived."

But, says Paulovic, like most things, poison is relative. "We have parents who call us saying that their kids ate four berries of holly. The toxicity in hollies generally causes a mild stomachache. Unless an individual eats a large quantity or has an extreme reaction, holly is usually only mildly toxic."

Ironically, a plant many people do think is poisonous, the poinsettia, is in fact non-toxic to animals or humans. This was indicated by a study at Ohio State University a quarter century ago. On the other hand, the Easter lily, found in grocery stores everywhere in the spring, is quite harmful to pets, especially cats.

Picking Flowers

In the end however, homeowners associations and their chosen landscaping professionals are generally diligent in determining which plants may be even mildly poisonous, and avoid cultivating them in common areas.

Paulovic recommends that homeowners associations avoid planting holly, or any other plants known to be toxic, where children might play, and adds that HOA managers and boards should specifically seek out landscapers who have Certified Landscape Technician, or "CLT" credentials. CLT-trained landscapers have the specific botanical training to identify poisonous plants.

But, "To be frank, the associations are anal," says attorney John Kwasnik, of Mezzacca, Kwasnik & Eichert in Metuchen. "It would be odd for an association to plant poisonous plants for any reason."

In 15 years of practice, and 10 years of just doing condominium law, Kwasnik has never known of a successful lawsuit from a case of ingesting poisonous plants. "No one goes through the trouble," he says. "We've had claims," he adds, "but unless a veterinarian is willing to testify," it usually goes by the boards, he says.

Furthermore, it is rare for a pet or child to eat enough of a poisonous plant to do themselves fatal harm. "Most poisonous plants are distasteful," says Dr. Marshall. "Most of the time, an animal will take one bite and spit it out."

That said, cats may eat toxic houseplants if they're bored enough, and dogs may eat poisonous outdoor plants if they are tied up outside, and hungry with no other food available. Thus, it's vital for pet owners to care for their furry companions by never leaving them chained up for long periods without access to food or real exercise.

Actually, the experts say, perhaps more dangerous than the plants themselves are the pesticides, the rodenticides, and the fertilizers used on plants, some of which can be harmful or fatal to both animals and humans. Other than the cases of cats eating lilies, Dr. Marshall sees more poisoning cases from these substances than from the other plants mentioned. Another common seasonal occurrence in New Jersey is emergency room visits for cats and dogs that have consumed antifreeze originating from a leaky car engine.

Luckily, most associations are, as Kwasnik says, extremely particular when it comes to what substances they use to treat their lawns and their gardens. And landscapers tend to play it safe when using pesticides and fertilizers: spraying on days when the wind isn't gusting, spraying downwind when the wind does pick up, and avoiding spraying toys, play gyms, sandboxes, or pet food dishes.

Furthermore, there is a trend towards the organic in today's society, and pesticides are no different. "Most associations investigate pesticides," says Kwasnik, "and they insist that their [landscaper] use just organic ones."

Protecting Yourself

How to protect yourself, your children, and your pets from poisoning?

Dr. Marshall recommends a thorough read of the ASPCA's Animal Poison Control Center web site, www.napcc.aspca.org, so that pet owners can familiarize themselves not only with which plants are and are not poisonous, but which parts of those plants carry the poison.

"Different parts of different plants are poisonous," she says. "In tulips and narcissus, it's the bulbs. In azaleas, it's the nectar from the flowers."

The Animal Poison Control Center is a 24-hours-a-day, seven-days-a-week, 365-days-a-year operation, staffed by veterinarians who are trained in poison control and treatment. Dr. Marshall advises keeping their toll-free number—(888) 426-4435—on hand.

Finally, she suggests assembling a poison safety kit, including vomit-inducing medicines and plastic gloves, in case a cat rolls in poison ivy and needs to be bathed, for example.

As for the little ones, here are a few tips on how to avoid incidents of poisoning from plants, as provided by the Children's Hospital of Pittsburgh:

Keep away from children.Obvious but important: keep unsafe plants out of the reach of youngsters.

Know your garden. Be familiar with which plants are and are not poisonous. If a landscaper is in charge of the garden, request pet-friendly plantings.

Store your seeds and pesticides. Keep seeds in bags, pesticides in their original containers, and both locked in a place pets and people can't get to them.

Wear gloves. Do this whenever working with plants, to avoid exposing yourself, and through you your children or pets, to plants like poison ivy.

Creating Green Space

While landscapers will continue to create elaborate landscape designs that please the eye, homeowner's associations should be careful to protect themselves from the danger certain plants pose to pets, to children—and to their pocketbooks, should litigation occur from negligence. Flowering plants, manicured shrubbery, and lush lawns all add to the luster of a condominium. By following a few simple rules, and knowing what to banish from your garden, the greenery can be enjoyed by all—pets and children included.

Greg Olear is a freelance writer living in Westchester County, NY.