Saturday, December 4, 2010

Greater Plantain Plantago major

I am an amateur naturalist trying to learn something about everything living in my garden.

Taken in August, photo 1 shows a specimen of the weed Greater Plantain (Plantago major) growing on my lawn. This plant is very common in the UK and likely to be encountered on any patch of rough wasteland (= my lawn!).

For such a common plant I have found relatively few freely available papers dealing with Greater Plantain on the web. There are a number (such as here and here) that deal with its medicinal properties. Plantago major appears to have a long list of antibacterial, antifungal and antitumeral properties and has even been recommended to treat the bites of rapid dogs! Amongst the interesting snippets I picked up from skimming the paper by Velaso-Lezama [1] is that Greater Plantain is today used as a medicinal tonic in Mexico having been originally introduced there by the Spanish conquistadors.

A number of species of Plantain grow in the UK including Ribwort- and Buck's Horn- , both of which have narrower ('lanceolate') leaves than Greater Plantain. Also Hoary Plantain (Plantago media) which as the name implies differs from Greater Plantain in having greyish down on the leaves. That at least is how things are set out in my copy of The Wild Flower Key (F. Rose, publ. Warne). If however, the Plantago media above is one and the same as the Plantago intermedia described in this paper [2] by El-Bakatoucshi, then these authors cast doubt on whether major and intermedia are sufficiently distinct to be regarded as separate (sub) species.

In skimming the paper above by El-Bakatoucshi , a word I came across that was new for me was protogynous (in context: "Plantago major is protogynous"). A little research and I now understand what this means. I'll share it here for interested readers: Firstly one has to recall that for many plants, the flower is typically neither male nor female. Rather the same flower combines male pollen producing parts (the anthers) and a female reproductive part (the stigma). This gives plants an issue of how to avoid self-fertilisation (i.e. self pollination). Plants have come up with a variety of solutions including i) Ignore the problem (= allow self pollination) ii) Separate your line into two, so that some plants carry only male and others only female parts (these are the so-called dioescious plants - from the Greek "two houses" . Our old friend the stinging nettle is an example) iii) Develop some "chemical / structural" approach that avoids self pollination. I wrote about a classic example when I discussed the two types of primrose, 'pin' and 'thrum' iv) Separate the time at which the male and female parts of a flower are active / receptive. This latter method ('iv') is protogyny and is the technique adopted by Greater Plantain. The female stigmas of Greater Plantain flower are protruded 1-3 days before pollen is produced and in this way the chances of self pollination are reduced. Another of those small but elegant behaviours Mother Nature has carrying on all around us.

[1] Effect of Plantago major on cell proliferation in vitro R. Velasco-Lezama, Journal of Ethnopharmacology 103 (2006) 36–42

[2] Introgression between Plantago major L. subspecies major and
subspecies intermedia (Gilib.) Lange. in a British population, R. El-Bakatoushi , Watsonia 26: 373-379 (2007)

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