TWO MYCOHETEROTROPHIC WILDFLOWERS

You probably know that plants are green because of chlorophyll in their leaves. It’s the chlorophyll that enables plants to convert carbon dioxide into food using the light of the sun.  A conceptually wonderful, simple plan that keeps our crops growing and evergreens ever green. It all works pretty well until one foolish species – Homo sapiens aka you and me – starts dumping more carbon dioxide into the atmosphere than the plants on Earth, including all those little ones in the ocean, can cope with. Then there is overload and the unabsorbed carbon dioxide forms a sheath around the planet, and that really messes with the climate.

But, that’s another story….

Green plants are autotrophs, which means that they produce their own food.

Some plants are not green. They’re called heterotrophs. They are bona fide plants, it’s just that they cannot produce their own food because they lack chlorophyll. So, how do they cope with this whole nutrient gathering thing?

Epifagus virginiana, beech drops or boom-rape parasitizes beech roots

Some of them parasitize the roots green plants. A common example in Deering is beech-drops, Epifagus virginiana¸ which parasitizes roots of beech trees.  The Epifagus draws its nutrients directly from the roots of the beech.  There are other less conspicuous examples of such plants in Deering.

 

 

 

Other heterotrophs get their nourishment indirectly from green plants through the intermediary of a fungus. These plants are mycoheterotrophs (myco = fungus). Monotropa uniflora, known as Indian pipe or ghost flower and Hypopitys monotropa, pinesap, are two mycoheterotrophs found in Deering. They parasitize mushrooms that have beneficial connections to trees. Appearances notwithstanding, both Monotropa and Hypopitys are related to blueberries.

Some plants, such as orchids, produce chlorophyll — so they can photosynthesize — but they also depend at least in part on being associated somehow, as parasites or some sort of mutualistic relationship, with mushrooms and mushroom relatives.  But, that is also another story.

Both Indian pipe and pinesap grow in dark, rich forests. Indian pipe is  far more common in Deering than pinesap. Both are parasitic on mushrooms but to appreciate this, you have to understand a little of mushroom biology.

Mushroom biology 101. The mushroom you see is only one part of the body of the mushroom. The mushroom you see is the result of sexual reproduction and is thus the part of the mushroom that holds the spores (which are roughly equivalent to seeds, but only roughly). You will never see most of the ‘mushroom’ because the real body of a mushroom consists of fine filaments that grow through the earth or decaying wood and other plant material.  This part of the mushroom, the fine filaments, is called the mycelium. The mycelium of many mushrooms form associations with the roots of trees. These associations are called mycorrhizae (myco = fungus and rhiza = root). The mycorrhizae are essential for tree growth because the fungus, as it scavenges in the litter, brings carbon nourishment to the tree. The tree sends beneficial goodies back to the fungus. So, it’s a mutually beneficial relationship for the two partners. Mycoheterotrophs, the Monotropa and Hypopitys, are interlopers that take and give nothing in return!

Monotropa uniflora is known as Indian pipe because initially the single white flower sits atop a white stalk opens downwardly, thus giving the plant the appearance of being a pipe. This plant is also are known as ghost flowers – or even corpse flowers – because of their translucent white color. One could well imagine the white stalks springing from some unspeakably horrible ‘thing’ in the earth.

Flowering of Indian pipe begins in spring and continues into the autumn. As the season progresses, the single nodding flower gradually turns upright. Pollination is effected by bees. Gradually the leaves turn black and eventually the whole plant becomes brown and dry. The old plants are common. Seeds produced in the capsule are wind dispersed when the capsule cracks.

The genus Monotropa differs from Hypopitys most conspicuously in the number of flowers produced by each plant, one in Monotropa and several in Hypopitys.

These mycoheterotrophs and partial mycoheterotrophic plants such as orchids, pinesap and Indian pipe, all produce very very small seeds, called ‘dust’ seeds. They are so small that, unlike larger seeds, have no or very little to provide the germling. After they are dispersed the seeds may lie in the environment for several years. During that time they may germinate, but germination rates are very low for these tiny seeds. While those that do germinate are developing they require a relationship with fungi to bring the germlings carbon nourishment. At first many fungi that live in the soil may be involved in this process, but over time there is more or less specialization with particular fungi. Thus Monotropa parasitizes members of the mushroom Russulaceae (Russula and Lactarius) while Hypopitys parasitizes members of the mushroom family Tricholomataceae. These mushrooms are all common fungi in Deering’s forests.

There is so much in the environment that we do not see. Amazing how life proceeds without our direct involvement. These processes are essential to cycling life. When we disturb some aspect of the environment, even a little, inconspicuous bit of it, we are messing with the cycle of life. The outcome is rarely good.

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