Wednesday, August 17, 2011

Opportunists

Last autumn I watched a bulldozer scraping away topsoil to level an area of building land, and made a mental note at the time to return this year to see what opportunist plants had established themselves on the bare soil. This one, common field speedwell Veronica persica, was well represented there. Usually the lowermost petal in this species is much paler, but this particular individual had exceptionally vivid blue flowers with deep blue, heart-shaped stamens. This species is an alien and was first recorded in Britain in 1825, and I imagine that its small seeds arrived on birds' feet, unlike .....























... this common sowthistle Sonchus oleraceus that must have staged an airborne invasion with its parachute-equipped plumed seeds.
I've been walking past this piece of land long enough to remember when it was arable land, with a wheat crop, and several of the other opportunists probably germinated from the residual seed bank of arable weeds in the soil ..... like this red-leg Persicaria maculosa....

...... this fumitory Fumaria officinalis ....

... and this field pansy Viola arvensis.

All of these are common and would be classified as weeds if they were competing with crop plants, but as colonisers of disturbed bare ground they're classed botanically as ruderals - species with constantly shifting populations that colonised disturbed habitats before more permanent vegetation establishes itself.

Common they may be, but the world would be a poorer place without them and just occasionally something a little less common reappears when the soil is disturbed.......

...... like this henbit Lamium amplexicaule which is much less abundant than it once was, thanks to the use of herbicides in intensive agriculture.

11 comments:

  1. That sowthistle looks fearsome in its reproductive fertility. Your henbit looks like the scurge of my lawn and garden though very pretty for the few days it all blooms in concert. My favorite from you today is the sweet white viola.
    nellie

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  2. The Speedwell is a glorious colour. So good to see things cropping up where ever there is a bit of bare earth.

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  3. Thanks again, the Sowthistle I saw today. if i see them they are common.

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  4. After starting work on our garden, we had loads of fumitory springing up and some of that little lamium also. I love Speedwell and have been transplanting some into bare patches of our lawn. :)

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  5. A dramatic shot of the Sowthistle.
    Henbit is a little beauty - I found some spring 2010 by Ryde canoe lake and thought the flowers resemble ladies in spotted headscarves.

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  6. Hello Nellie, those little white violas are lovely, aren't they?

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  7. Hi Toffeeapple - it's always been a favourite of mine.

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  8. Hi Adrian, I always think that its when we stop seeing the common things that then the environment is really in trouble..

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  9. I'm with you on speedwell in lawns Lesley - makes them much more interesting. Slender speedwell Veronica filiformis thrives in lawns, because when you mow it all the cuttings take root....

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  10. Hi Rob, whenever the soil around the university science site in Durham is disturbed henbit usually turns up somewhere, along with bugloss and field madder - they must have long-lasting dormant seeds

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  11. Oh, I don't know henbit, such a pretty wee flower.

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