Alien Plant Invasions and the Extinction Trajectory
This is a really interesting post on the Awkward Botany blog about alien species and the possibility of plant extinction.
In our current ‘Extinction or Survival?’ exhibition we have illustrated this potential threat to species using the stories of the red squirrel and the white-clawed crayfish in the UK, but of course competition with invasive species is a potential risk for plants too.
One of the concerns about introduced species becoming invasive is that they threaten to reduce the biodiversity of the ecosystems they have invaded. They do this by spreading rampantly, using up resources and space, altering ecosystem functions, and ultimately pushing other species out. In the case of certain invasive animals, species may be eliminated via predation; but plants don’t eat each other (generally), so if one plant species is to snuff out another plant species it must use other means. Presently, we have no evidence that a native plant species has been rendered extinct solely as a result of an invasive plant species. That does not mean, however, that invasive plants are not doing harm.
In a paper published in AoB Plants in August 2016, Paul O. Downey and David M. Richardson argue that, when it comes to plants, focusing our attention on extinctions masks the real impact that invasive…
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Beautiful Lady’s Slipper Orchids
The Passo Pura in the Carnic Alps was awash with summer flowers when we visited for our Field Course in Alpine Biodiversity and Forest Ecology in July. One interesting walk took us up this seasonal stream bed on the side of Monte Tinisi and rewarded us with some beautiful Lady’s Slipper Orchids (Cypripedium calceolus).
The flowers in the hot Italian sun were fading and drying up, but the plants in the shade were perfect.
I’d only ever seen this plant in cultivation before, so it was a treat to see it growing wild. In the UK it is very rare having been lost from many sites through 19th century collecting for the horticultural trade. The lady’s slipper orchid was thought extinct in the UK until a plant was found growing at one site in Yorkshire. This plant has been the focus for conservation and re-introduction programmes.
We also have pressed examples of this species in the herbarium collection and one sheet is on display in the Living Worlds gallery. This example was collected in the same area of the Carnic Alps in 1897 by James Cosmo Melville. He didn’t do a very good job of pressing the intricate 3D flowers, which is one reason why orchid flowers are often preserved in spirit collections.
This specimen collected from neighbouring Austria does a much better job of showing the structure of the flowers. However, the person who picked it also included the roots (not just examples of the leaves and flowers) which could have had consequences for the population of plants at that site. Like other orchids, germination needs the presence of a symbiotic fungus and the lady’s slipper orchid can take many years before it reaches flowering size.