Cow-wheat and Beech-drops, two parasitic flowering plants

Most plants produce their own food by taking carbon dioxide from the air and transforming it, via chlorophyll and photosynthesis, into sugar. Some plants lack chlorophyll and the ability to produce their own food. They need to get nourishment from somewhere, so they parasitize other organisms, including plants and fungi. They form specialized structures that enter the roots of their plant hosts and steal nutrients.  Still other plants have both a parasitic and a photosynthetic ability. They have chlorophyll and can make some food, but they still need to get nutrients from other plants. These plants are called ‘hemiparasities.’

Two native plants that are common in Deering are members of a whole family of plants that are parasites on roots of trees: narrow-leaved cow-wheat and beech-drops.

Melampyrum lineare, also known as narrow-leaved cow-wheat, is a hemiparasite because it has chlorophyll, but still it enters their roots and parasitizes several species of pine, poplar, sugar maple, red oak and low-bush blueberry. This small, native, woodland annual has flowers that resemble a snakes head. The small yellow flowers are more or less tubular and are pollinated by long-tongued bees. Cow-wheat is found in man-made or disturbed habitats, cliffs, balds, or ledges, forests, grassland, meadows and fields, sand plains and barrens, woodlands. In Deering I have found it growing in an exposed spot along the Hedgehog Ridge Trail and in meadow along the trail through the Wilkins-Campbell Forest. Certainly it grows elsewhere in town. Our cow-wheat is native to North America. The plant occurs in most of the eastern states as far west as Illinois and Wisconsin, south to Georgia, and across Canada; it also is found in Montana, Idaho and Washington. The name Melampyrum (dark seed) refers to the black seed that is produced by some species and this seed can sometimes get into harvested grain, thus ‘cow-wheat.’ An European species of cow-wheat, M. pratense, also parasitizes roots of pine trees. One study found that these cow-wheat plants were much healthier when parasitizing trees that had associations with some fungi (mushroom species) through their roots than when parasitizing trees that lacked these ‘mycorrhizal’ associations. The conclusion was that the mycorrhizal fungus enables the tree to produce more nutrients than the unassociated trees, and these nutrients are transported to the parasitic cow-wheat plant.

 

Epifagus virginiana, beech-drops, a relative of cow-wheat, is an annual herb that depends on getting its nourishment from the roots of beech trees. Thus it is a host-specific parasite. In Deering you can find beech-drops everywhere beech trees are found. It appears as leafless (the leaves are reduced to scales), brown plants growing up from around beech trees. Plants of beech-drops occur singly or in clusters and are often densely disposed around the tree; typically 8 – 12” tall, they can get as tall as 18”. Flowering occurs late in the year, August through October. Flowers are small and trumpet-shaped, striped in red and purple. They arise singly along the stalk. Toward the base of the stalk there are flowers that do not open. These ‘cleistogamous’ (hidden gametes) flowers are capable of self-pollination. At the end of the season the whole plant becomes brown and brittle. One study found that the plant is pollinated by various insects but the most common species observed in that study was Prenolepis imparis, winter ant. The winter ant avoids competition with other ants by only becoming active when temperatures fall and other ants are less active …. and beech-drops is flowering.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.