Close connections in the Plant World
Geri O'Brien Plant Rescue Team

Dodder from the University of Georgia Plant Pathology Archive, University of Georgia Plant Pathology Archive,UGA, Bugwood.org

At the mention of "parasite," chiggers, ticks and fleas are likely to come to mind. Probably not buffalo nut, dodder and mistletoe, three of the 4,000 species of known plant parasites.

Of the three, mistletoe is the most familiar. These evergreen shrubs grow on a variety of deciduous hardwoods and are quite visible in the top limbs of oaks in North Georgia during winter. They are a native species known as American mistletoe, one of the major groupings of the thousands of known species. Botanically, they are a partial or "hemiparasite", because they have chlorophyll and carry out photosynthesis, taking only water and mineral nutrients from the host plant. Harmful effects of mistletoe on the host may not be evident for several decades, in which time it has provided food and nesting sites for the birds and squirrels which help to spread its seeds. Highly toxic to humans, it nonetheless has been used in medicine by both Europeans and Native Americans. A very ancient plant, it has a rich history in legends, including the holiday one of kissing under the mistletoe.

Submitted photo by Geri O'Brien/ Plant Rescue Team Mistletoe

Whereas mistletoe is a stem parasite, buffalo nut, Pyrularia pubera, is a parasitic shrub that grows on the roots of deciduous hardwoods and some conifers. Not nearly as conspicuous as mistletoe, it is a puny looking understory shrub that reaches about six feet in height and spreads by thick lateral stems on top of the ground. Buffalo nut is also a hemiparasite and is a native plant in parts of nine states, from Pennsylvania to Alabama, where it is variously listed as endangered, rare, or secured. Interestingly, it is known as an exotic invader in New York. Georgia does not list the conservation status of the shrub, but it doesn't seem to qualify as an "invader" here in the hills where it might appear in places where forests were disturbed in the past, such as old roadbeds and long-deserted hog lots. It could easily go unnoticed were it not for the occasional little green fruit that shows up in late summer. The fruit is highly toxic to humans, though deer and other animals safely ingest it. Buffalo nut, too, had a role in herbal medicines of early colonists and the Cherokees.

Submitted photo taken by Dr. Paul Arnold, Young Harris College Buffalo Nut

In contrast to mistletoe and buffalo nut, dodder is a holoparasite, a plant that is completely dependent on other plants. It is a stem parasite of many different hosts, and over 100 species of the genus Cuscuta are found in temperate and tropical zones of the world. Dodder consists of yellowish orange stems which wind around the host plant, sometimes in large netlike masses. Here in the mountains it might occasionally be seen along the edges of fields or roadsides, but it may enter the garden and attack ornamental plants. In some areas it is a major pest of crops, attacking onions, peas, beans, and potatoes, to name a few of its favorites. An annual, dodder reproduces by minute seeds formed from tiny white flowers in late summer. The seeds can lie dormant for several years, but when they germinate, the seedlings must find a host within a day or two or else they die. Research indicates that dodder uses airborne chemicals to locate a proper host, somehow "smelling" those tomatoes, chrysanthemums and petunias.

These stringy, leafless twiners have been used in herbal tonics and in poultices to treat pain of joints and muscles.

Parasitic plants are not likely to be high on the list of plants to rescue, and in this area these three are fortunate enough not to need it. Whether one's inclination is to consider them a blessing or a curse, they are naturally occurring oddities in the wonderful world of plants.

For information on the Plant Rescue Project sponsored by the Preservation Committee of The Community Council of the Georgia Mountain Research and Education Center, contact Jennifer Cordier (706-745- 9317 ivylog@alltel.net) or Glen Henderson (abletinker@aol.com).