• The Montreal Botanical Garden grows poison ivy.Ken Samuelsen/Photodisc/Getty Images
  
  Botanical gardens are formal collections of plants, arranged for attractive viewing and used for scientific study. Botanical gardens are often located at historic estates, or on the grounds of universities that feature horticultural study. If you are searching for something a little different for your next landscaping project, take a look at some of the unusual plants grown in botanic gardens across the United States.
  
  

Poison ivy

• The Montreal Botanical Garden grows poison ivy --- on purpose. Poison ivy (Toxicodendron radicans) is just one of the dozens of plants featured in this botanic garden's Toxic Plant Garden. Poison ivy would be considered by many an attractive, glossy-leaved vine, were it not for the profound itching and blistering reaction it causes on contact with skin. Other unusual plants in this fenced poison garden include jimson weed (Datura stramonium), a hallucinogen with beautiful large white flowers, and red baneberry (Actaea rubra), a shrub with lacy leaves resembling elderberry, but with stalks of glossy red berries that can cause cardiac arrest. The Montreal Botanical Garden warns visitors not to touch these toxic plants.
  
  

Hoodia

• Hoodia (Hoodia gordonii) is a plant that has been in the news as a potential appetite suppressant, and is added to numerous commercially marketed diet aids. The plant itself is a carrion flower, meaning that its large, dull-pink flowers send out a fetid odor to attract pollination by insects that otherwise swarm to rotting flesh or feces. The Moorten Botanical Gardens, a former estate in Palm Springs, California, grows hoodia in its collection of more than 3,000 species of specialized plants that thrive in hot, dry desert conditions. Among the other unusual plants grown at Moorten is the Welwitchia mirabilis, a primitive tree that bears only two leaves, which grow continually from their base for up to thousands of years.
  
  

Corpse flower

• The corpse flower (Amorphophallus titanum) is the most striking and unusual carrion flower, if not the most unusual plant in general. Specimens can be found at the New York Botanical Garden, the Brooklyn Botanical Garden and the gardens at Western Illinois University, reports the New York Daily News online. Additional corpse flowers are found at the Huntington Botanical Garden in San Marino, California, and the Fullerton Arboretum at the California State University at Fullerton. However, always call to make sure the corpse flower is blooming before you plan your trip to see it --- this native of Sumatra only blooms once every 15 years or so. That may be a good thing. Corpse flowers have a burgundy pleated spathe, or giant "petal," that's approximately 4 feet tall and 12 feet around, from which towers a spadix more than 8 feet tall. The most overwhelming thing about the corpse flower is not its size, however, but its smell. Visitors have been known to pass out from breathing its stench, according to botany professor Wayne P. Armstrong of Palomar College, California.