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“Nature’s war” and Common Whitlowgrass

18 March 2012

With snow behind, this tiny plant is flowering on 4th of February

This tiny flower is common whitlowgrass, Erophila verna, a brassica, found across the northern hemisphere, and I expect introduced in many other places by accident. According to everything I have read flowers from March to June.

However, quite clearly it flowers even in February, and almost certainly in January, at least this year, as you can see the small seed pods which look a bit like pea pods on these photos taken in early and late February. I am fairly ignorant of botany, (and much else) and as usual I go to one of a number of books to try and identify species I come across. This is such a small, one might say insignificant plant, that it might be thought well understood. However it seems that identifying it as one species has never been simple, and it has been split into three species. The genus is widespread. I find something like this and then I want to know where it fits in with other species – what pollinates it – itself, insects, wind? What eats it? How do the seeds get distributed – insects, winds, animals? Questions are a good thing, for the more you know the more you wish to know more, and the urge to dis-cover [sic] is deep within humans. Many humans. (I confess, I get annoyed by willful ignorance.)

'Y' shaped hairs on the leaves. Why?!

Usually the identification books fail you as far as detailed information about A plant goes, as they are really only field guides with a short page and a bare few details such as flowering, location, distribution, and none that I have suggests much further reading for each plant. There is a nice piece about this flower here and a few articles are listed here – Kew. As for the name – plant names seem such a ‘mess‘! Read about plant ‘accepted’ names and synonyms here. See Botanical Society of the British Isles here. From the International Plant Names Index, it seems it was named by Linnaeus then reclassified by Augustin de Candolle, the Swiss botanist. Darwin knew him and corresponded with his son Alphonse.

One interesting short article I found, ‘Population Cycles Caused by Overcompensating Density-Dependence in an Annual Plant’ by E. Symonides, J. Silvertown and V. Andreasen in Oecologia 1986 Vol.71 (1)156-158, says that they studied E.verna for seven years, observing these cycles based on overcrowding in one year and subsequent drop the following year. The numbers of plants in the study went from 1-2 to 55-65 individuals per plot, or rather the other way around! No significant numbers of seeds survived in the soil after the main flush of germination, so seed that developed on the plants in a season became the next generation. They estimated that the seed germination was between 1 and 3%. Plots where there was low or no cycling were predicted to have poor conditions, while better conditions produced the boom/bust. This is “competition max” if you like. “Nature’s war”, was is a concept developed by de Candolle, but he saw it as inter-specific, while Darwin took it further, seeing it also as intra-specific. “The face of Nature may be compared to a yielding surface, with ten thousand sharp wedges packed close together and driven inwards by incessant blows, sometimes one wedge being struck, and then another with greater force.” (Origin, Chapter 3 p.67 of 1st edition, dropped thereafter). In his Natural Selection notebook Darwin had written,

Nature may be compared to a surface covered with ten‐thousand sharp wedges, many of the same shape & many of different shapes representing different species, all packed closely together & all driven in by incessant blows: the blows being far severer at one time than at another; sometimes a wedge of one form & sometimes another being struck; the one driven deeply in forcing out others; with the jar and shock often transmitted very far to other wedges in many lines of direction: beneath the surface we may suppose that there lies a hard layer, fluctuating in its level, & which may represent the minimum amount of food required by each living being, & which layer will be impenetrable by the sharpest wedge.

  1. i have this plant in my yard. it’s called a nicotiana plant.

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