The strategy devised by the plant is amazing. For example, what do the following plants have in common: dodder (love vine), mistletoe, squaw root, beech drop, pine sap, gerardia, single ganzu, foxglove, and Indian paintbrush?
Answer: All are parasitic on the vegetative systems of other plants.
The word “parasite” comes from the Greek word meaning “eating at someone else’s table”.
A plant is parasitic if it obtains all or part of its food from an invading host.
Many parasites invade host plant tissues through special structures called ‘haustoria’. These structures, which resemble blunt hypodermic needles, can be easily observed when the willow vine is unwound from its host.
Some parasitic plants prey on a variety of host plants. Mistletoe can be found on the branches and trunks of many different trees. Indian paintbrush grows in open areas where it can invade a variety of grassroot systems.
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When a plant is “epiphytic” it simply lives on top of another plant and gains access and support from rain and sunlight. Mosses, lichens and ferns are good examples of epiphytes found here in temperate climates. However, in rainforests, many orchids and bromeliads are completely epiphytic.
When a plant gets only part of the nutrients it needs from the host plant, it is called a “hemi-parasite.” For example, mistletoe obtains water and mineral ions from its host, but produces carbohydrate nutrients through the photosynthetic activity of its abundant green leaves. Still other parasites form complex ‘mycorrhizal’ associations involving intermediate fungal agents in the host plant and soil, such as the example of the pink and yellow lady’s slipper.
Some parasitic plants are “species specific”. That is, it grows only in a single species of host plant. Foxgloves, for example, only eat the root system of oak trees.
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One of the most interesting endemic plants found here in the southern mountains is the beech (Epifagus virginiana), which begins to bloom around this time. If you have beech trees on your property, you may be able to find them growing under them.
Look for drab, low-growing (6 to 18 inches tall) plants with brownish-tan stems and lots of magenta flowers. Blooming from August to October, these flowers are delicately patterned and can be fully appreciated by hand through a lens.
Note that the flowers at the top of each branch open to attract insects for cross-pollination. The lower flowers remain closed. These are “closed-uncrossed” flowers that self-pollinate in case the ideal cross-pollination scheme doesn’t work.
This column was originally published on August 18, 2021.
George Ellison is an award-winning naturalist and writer. His wife, Elizabeth Ellison, is a painter and illustrator who has her gallery studio at 155 Main Street in Bryson City. Contact info@georgeellison.com or info@elizabethellisongallery.com or write to 3880 Balltown Road, Bryson City, NC 28713.
