Native Forest Plants for All Seasons
As the last leaves fall from the trees leaving the forest bare for the winter’s freeze, many summer season plants go dormant. They retreat with their nutrients under the soil and leaf cover to wait until spring. There are some specialists out there that persist over winter. They allow us a fascinating glimpse into the mutualistic relationship between these plants and the fungi that aid in their life cycles.
These plants can, of course, be found alone but once your eyes zoom in it’s amazing how many are hidden in the leaves. Often they grow in large scattered groups that correspond with root and mycelium networks underground. Some of these plants could easily be overlooked during the lushness of summer but are more prominent in the autumn and winter woodlands.
The downy rattlesnake orchid (Goodyera pubescens) can be found in deciduous and coniferous forests. This eye-catching plant has silvery veins and is covered in fine hair. As with all orchids, fungi play an essential role during the downy rattlesnake orchid’s entire life cycle. It requires complex associations with specific fungi in order to germinate and grow. Their seeds are tiny with limited nutrients so the soil fungi provides energy until the plant breaks through the surface and can begin photosynthesizing with its leaves. Still, the fungi will continue to provide nutrients from the soil while the orchid feeds the fungi carbohydrates. This downy rattlesnake orchid flowers in late summer, though it takes the new rosettes several years to get to this stage. After flowering a distinctive seed pod is produced which lasts for many months.
Cranefly orchid (Tipularia discolor) and putty root orchid (Aplectrum hyemale) have non-photosynthetic flowering shoots. Getting to know their leaves in the winter is the best way to remember where their ethereal inflorescences will appear in the summer after the leaves have died back. These orchids only do their carbon acquisition via photosynthesis when their leaves are out from fall to spring. During their flowering stage all energy comes from their symbiotic relationship with mycorrhizal fungi rather than carbon fixation. This means they are partially myco-heterotrophic.
The cranefly orchid uses rotting wood as substrate for germination because they have a relationship with a type of fungus that decomposes wood. This orchid spends most of the year as a single leaf. Though it blends in during the summer it is relatively easy to spot in the winter as the enticing leaf stands out on the forest floor. If you see this leaf, you will often notice raised purple spots and can check underneath for a rich purple to confirm its identity. Return to this location in late summer to look for the subtly intricate asymmetrical flowers this orchid makes after the leaf dies back. Though many orchids have bilateral symmetry these differ to make sure their nocturnal moth pollinators are the only ones to collect the pollen during their short bloom time. When the moth reaches into the nectar spurs, the pollen sticks to the moth’s eyes to help assure it is transferred only to another orchid.
The Putty root orchid has a bigger leaf that is lined with silvery, green and white veins. These silvery leaves are produced from corms (underground storage organs) and thrive with the low photosynthetic levels of winter woodlands. This plant shares the mycorrhizae of nearby trees to obtain nutrients which is essential when the leaves have decomposed and the non photosynthetic flower shoot begins to grow in early summer. The flowers on the stalk do not have nectar spurs as they do not need to attract specific pollinators. Putty root orchid is self fertile – though various bees do visit the flowers.
While these orchids spend a portion of their lives without photosynthesising, there is another group of plants whose entire life is spent this way. These are called obligate (or full) heterotrophic plants. Their intriguing husks often remain for the winter and into the next growing season.
Ghost pipe (Monotropa uniflora) is a plant that can be easily mistaken for a mushroom with its otherworldly fleshy appearance. This wildflower lacks chlorophyll and obtains all of its nutrients from tree roots through a mycorrhizal fungal relationship making it an obligate myco-heterotroph. The mycelium that the ghost pipes interact with is specific to the Russulaceae family of mushrooms. An abundance of mushrooms in this family is a sign that there are likely many ghost pipes in the area. (Here are iNaturalist links to the two most common genera in the family: Russula and Lactarius – both of which have hundreds of species here in Virginia). Ghost pipes emerge in the summer with a downward facing flower. Bees pollinate the flower by hanging on it upside down. After pollination the flower points upwards. By winter the ghost pipes are no longer translucent but rather a woody stock with a seed head that blackens over the winter. Though a lot of people may be familiar with ghost pipes, there are many other non photosynthetic plants native to Virginia that are just as alluring.
Beechdrops (Epifagus virginiana) attach to the shallow roots of American beech trees (Fagus grandifolia), to get nutrients and grow, often in great numbers. They hide in plain sight but once you know them you’ll see them everywhere in beech filled forests, especially surrounding older trees. Beech trees have smooth gray bark even as they mature. Their green serrated leaves turn yellow/tan in fall and winter and stay on the juvenile tree until spring, making them easy to spot. Like ghost pipes, the fleshy summer form of beechdrops dries and hardens as they mature to release their seeds. It is suspected that ants are involved in their proliferation. Their woody forms often stay all winter and into the spring before they decay and new growth begins. The beech tree actually releases a chemical signal that triggers beechdrops to germinate. It takes a few years for the above ground structure to break the surface after germination. During this time beechdrops rely on nutrients from the seed rather than the tree. For the rest of the beechdrops’ life they rely on their host tree for nutrients but this does not negatively impact the host, in fact the presence of beech drops indicates a healthy forest.
Bear corn (Conopholis americana) is another fascinating heterotrophic plant whose thick stalks look like ears of corn or pine cones. Each “corn” capsule contains many seeds. Black bears and deer will eat this plant and disperse the seeds. Bear corn seeds, like beech drops, must be near tree roots in order to germinate. In bear corn’s case its host is usually oak trees. They use specialized roots called haustoria to obtain nutrients from their host tree without causing issues for the tree. As winter comes along the fleshy corn like plant dries up to black husky spikes that will persist until spring. In late spring the plants that have been growing underground for four or so years break through the surface and the flowers form a few weeks later. Some pollinators may come by but bear corn is self fertile.
Hopefully you will be able to spot a few of these species over the course of the cooler months and greet them as friends when they bloom in the warmer months. Giving proper attribution to the fungal networks helps us to see enchantment living in the forest, no matter the season.
Featured photo: Bear corn in winter. Photo: Kaila Pennock
Wildflower of the Year 2016 Downy Rattlesnake Plantain (Goodyera pubescens) Virginia Native Plant Society
Goodyera pubescens (Downy Rattlesnake Plantain, Rattlesnake Plantain) |North Carolina Extension Gardener Plant Toolbox
Orchids: Masters of Deception –North Carolina Botanical Garden
Importance of Woody Debris in Seed Germination of Tipularia discolor (orchidaceae) – American Journal of Botany
A Real Hidden Gem: Cranefly Orchid (Tipularia discolor) – Durham Master Gardeners
Aplectrum hyemale (Adam and Eve, Putty Root): Go Orchids– North American Orchid Center
Ghost Pipe – Plant-of-the-week – U.S Forest Service
Taxa – Russula – iNaturalist
Taxa – Lactarius – iNaturalist
Woodland Weirdos North Virginia Department of Forestry
Beechdrops – A Native Parasitic Plant Extension Marketing and Communications
Epifagus virginiana (Beach Drops, Beech-drops) North Carolina Extension Gardener Plant Toolbox
Conopholis americana (American Cancer-root, Bear Corn, Bumeh, Cancer Corn) North Carolina Extension Gardener Plant Toolbox