Saturday, August 4, 2007

Cultivated Oat Avena sativa

I am an amateur naturalist trying to learn a little about everything that lives in my garden.

A small clump of oats is growing in my garden (at (0.8,0.6) - see here). Since this spot is below my bird table where I hang a feeder of mixed seeds, I suspect they sprouted from the fallen seed.

A number of oat species are found in Britain and I understand that hybrids are not uncommon. I don't have the expertise to identify my oat with absolute confidence, but I'm going with the Cultivated Oat (Avena sativa) based on the smooth, hairless spikelets (the 'heads' in photo 1) and description in my copy of Grasses (Fitter, Fitter, Ferrer, publ. Collins).

In my last posting I spoke of my pleasure of learning for the first time that grasses are flowering plants. Old news to you all out there I'm sure - previosuly I'd not taken the time to register grass as being anything more than 'green stuff' (though in retrospect I admit the fact that grasses produces pollen, hence hay fever, ought to have been a pretty big clue).

If there is an excuse for my ignorance, it is that grass flowers tend to be rather tiny, unfamiliar in appearance and get labelled with a complex terminology. Having acquired my new knowledge however, I have been determined to get to grips with the details, and accordingly Photo's 2,3 (click to enlarge) show my attempt to dissect an oat spikelet. I don't doubt for a moment that exactly the same subject matter is presented, and better, in innumerable botany text books out there. Since I'm trying to learn a little about the natural history in my garden for myself however, and blog my experience of doing so, I don't feel the need to apologise for repeating it here. So there!

The two outermost 'leaves' (except they're not true leaves) of a grass spikelet are called the glumes. The two may differ in length (which can be a useful clue when trying to decide the species of a grass). The glumes enfold one or more florets each of which consists of a two leaf-scales called the palea and the lemma. A long thin awn may emerge from the lemma.

In between the palea and the lemma (see photo 3) sit the anthers and ovary (the male and female reproductive parts of the grass). It is the anthers that split open to liberate pollen. Under a microscope (photo 4, 40x magnification) you can see one of the yellow anthers doing just that.

And that, as they say, is that! In all however, probably best to stick with roses for those special occasions: I find a box of porridge oats tends not to have the same impact.


Laura said...

Interesting observation. I was of a similar frame of mind on the green phenomena. What a wonderful thing is a bit of retrospect.

Henry Walloon said...

Indeed Laura, who would have thought, for example, that leopard slugs would be the racy creatures your site reveals them to be!

Laura said...

Yeah! My face reddens at the thought of gastropods getting their oats...