Sunday, July 04, 2010

anthocyanins



This group of Wall Barley (Hordeum murinum) at the foot of a lamp-post was very eye-catching in the red light of dusk, though my camera could only gesture at it.

The next day I went back a couple of times to try again - a bit furtively, since the street corner is constantly overlooked and taking photos of weeds is obviously eccentric behaviour.



Wall Barley always seems to grow in places where dogs piss, but whether the unusual amount of red in these plants has anything to do with being pissed on, or with some other polluting accident (petrol, White Lightning), I don't know. (When nettles are pissed on it sometimes turns them pale yellow; dog-owners come to accept brown patches on their lawns.) [NB written a couple of weeks later: - In the Swedish fells I noticed a grass that I suppose was Poa alpina whose panicles were very strikingly coloured, sort of rosy-pink as well as strawy - I forgot to photograph it.]

And where did wall barley grow before human beings existed? Difficult to imagine it in Britain, - perhaps around a few dry rock exposures? - I rather imagine it was a latecomer from the dry south, eagerly colonizing our primitive clearings.



More or less unconnectedly, here are some plants whose anthocyanins went missing. This rather surprising plant is Herb Robert (Geranium robertianum), found in Savernake Forest.



(Here's what it normally looks like: - remember?)





And this plant is, of course, not White Campion (Silene latifolia) but white Red Campion (Silene dioica). Obviously in this case the context is a massive clue. The other clue is that a white Red Campion usually contains no anthocyanins, so its stem and calyx are pale green. By contrast, the white petals of White Campion are as a rule prettily contrasted with the wine-flushed calyces.

These are only probabilities. For two species so different in character and habit, (and in normal circumstances so instantly distinguishable), a cast-iron diagnostic difference is surprisingly hard to pin down. The main one concerns the capsule-teeth...



These ones are revolute not erect, proving the plant to be red campion. But you need to wait for mature fruit before you can see it.

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3 Comments:

At 12:05 pm, Blogger Vincent said...

You are a man after my own heart, Michael. Ever since your piece about the metamorphosis of the dandelion flower into the dandelion clock, I have been watching these kinds of transformation as best I can.

My latest hobby is watching grass grow - not continuously I should add. Having put down some grass seed on the bare patches in my lawn, and endeavoured to keep it moist without covering it over, I've been able to see its neat method. The root comes out of one end, and anchors itself in the soil which makes the other end rear up and throw up a shoot from between the dry husks. The simplest things seem the most miraculous. There must be a symbiotic relationship between the common grasses and the animals which graze on them.

The engineer Eric Laithwaite many years ago did a TV programme "Gaze in Wonder", and spoke of the way grass engages in spread-betting to ensure survival. Of the same species and variety, he said, some exemplars grow tall before going to seed, whilst others don't take the risk (they might be eaten by a goat first) so they see very low. And there was a third strategy in the middle. I can't remember the rationale.

So I wonder if there is any symbiotic relationship between weed and pissing mammal, of mutual benefit.

 
At 1:18 pm, Blogger Vincent said...

Damn, I meant "seed very low", not "see very low".

 
At 1:30 pm, Blogger Michael Peverett said...

Well I've almost wrecked my knees grubbing 50,000 daisies out of a lawn and they too definitely do the spreadbetting thing. A hugely absorbing occupation, getting to know these daisy roots. While my fingers were intellectually so stimulated, the rest of my mind slept peacefully, only vaguely disquieted by the question "what 's so special about daisy roots"? The suggestion of some experts that the original cockney slang for boots was "daisy recruits" is even more mystifying.

 

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