Northumberland Diary Discussion: 26 October 2014
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Northumberland Diary. Entry 286.Go to latest contribution by John Good, 06 November 2014, 10:19. Go to bottom of this page.
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Lloydia still occurs in a number of sites in N. Wales, almost always on damp, N or NW facing cliffs. Here is a photo of a plant growing in the so-called 'Hanging Gardens', a few hundred yards to the rt of your photograph of the Devil's Kitchen'. Dr Barbara Jones, a retired former employee of the Countryside Council for Wales (now sadly subsumed into the all-embracing Natural Resources Wales, and a member of our N. Wales Group of the AGS, did her PhD on the ecological genetics of this species and produced some very interesting results.
Yes indeed, I remember Barbara and her work very well. One of her more remarkable results was the finding that Lloydia is androdioecious, that is males and hermaphrodites coexist in the population (or put another way, the population is polymorphic for female sterility). Gynodioecy (females and hermaphrodites) is a fairly common situation; all plants can act as a mother, but androdioecy should not be successful (theoretically) as males are at a reproductive disadvantage. However, this assumes that plants reproduce from seed. I know of only two cases of androdioecy, the other being another rare alpine Saxifraga cernua, and in both cases most if not all reproduction is vegetative (Sax. cernua has bulbils). In these cases, males are favoured as their reproductive load is lighter than that of females.
One may ask why dioecy (males and females) can succeed if androdioecy should be unsuccessful. This is because females have no male function, so that male/female contribution to the next generation is theoretically equal.
Don't we all have fun?