Clonal colony

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A clonal colony or genet is a group of plants (or a fungal mycelium) that has grown in a given location, the "individuals" which are all genetically identical, originating vegetatively and not sexually from a single ancestor. Individuals in these populations are referred to as a ramet. In the case of a fungus, "individuals" typically refers to the visible fruiting bodies or mushrooms, these over a wide area developing from a common mycelium spread over a large area, hidden in the soil. Clonal colonies are common in many plant species. Although many plants reproduce sexually through the production of seed, some plants reproduce by underground stolons or rhizomes. Above ground these plants appear to be distinct individuals, but underground they remain interconnected and are all clones of the same plant. However, it is not always easy to recognize a clonal colony especially if it spreads underground and is also sexually reproducing.

Methods of establishment

  • With most woody plants, clonal colonies arise by wide-ranging roots that send up new shoots, termed suckers at intervals.
  • Trees and shrubs with branches that touch the ground can form colonies via layering, e.g. willow and blackberry.
  • Some vines naturally form adventitious roots on their stems so can easily send roots into the soil when the stems contact the ground, e.g. ivy and trumpet vine.
  • With other vines, rooting of the stem where nodes come into contact with soil may establish a clonal colony, e.g. Wisteria.
  • Ferns and many herbaceous flowering plants often form clonal colonies via horizontal underground stems termed rhizomes, e.g. ostrich fern Matteuccia struthiopteris and goldenrod.
  • A number of herbaceous flowering plants form clonal colonies via horizontal surface stems termed stolons, or runners; e.g.strawberry and many grasses.
  • Nonwoody plants with underground storage organs such as bulbs and corms can also form colonies, e.g. Narcissus and crocus.
  • A few plant species can form colonies via adventitious plantlets that form on leaves, e.g. Kalanchoe daigremontiana and Tolmiea menziesii.
  • A few plant species can form colonies via asexual seeds, termed apomixis, e.g. dandelion.

Record colonies

The Pando Quaking Aspen (Populus tremuloides) clone in the Wasatch Mountains, Utah, USA, is sometimes considered the world's largest organism by mass, covering 43 hectares. It is possible that other unknown clonal colonies of trees rival or exceed its size, though their status as single individuals.

The only known plant of King's Lomatia (Lomatia tasmanica) in Tasmania is a clonal colony claimed to be 43,600 years old. Another possible candidate is a strand of the marine plant Posidonia oceanica in the Mediterranean Sea, which could be up to 100,000 years of age.[citation needed]

Examples

When woody plants form clonal colonies, they often remain connected through the root system, sharing roots, water and mineral nutrients. A few non-vining woody plants that form clonal colonies are:

References

  • Cook, R. E. (1983). Clonal plant populations. American Scientist 71: 244–253.
  • Kricher, J. C., & Morrison, G. (1988). A Field Guide to Eastern Forests, pp. 19-20. Peterson Field Guide Series. ISBN 0-395-35346-7.

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