Thursday, July 05, 2018

glumes and lemmas

Squirrel-tail Fescue and Great Brome

At the week-end I was up in N. Yorks, and while I was there we had a sunny walk from Kilburn to Byland Abbey and back via Oldstead, essentially the same walk I did four years ago:

Anyway, this time I was on the lookout for grasses and I returned south with a bunch of grasses in a "vase" (plastic drinks-bottle).  It took me a week to get round to inspecting them (with grasses, it doesn't matter too much from the ID point of view if the material is a bit dried up). And the bunch seemed to contain two species I've never knowingly seen before.

Squirrel-tail Fescue  (Vulpia bromoides)  is actually the most widespread of the Vulpia genus in the UK, especially in the countryside, but the only one I knew was Rat's-tail Fescue (V. myuros), which has become pretty common in urban environments. The chief diagnostic difference relates to the relative sizes of the two glumes, which in V. bromoides are reasonably well matched, whereas in V. myuros etc the lower glume is extremely small. (Additionally, V. bromoides has a shorter, more erect, inflorescence, beginning well above the uppermost leaf-sheath.)

Great Brome (Anisantha diandra, previously known as Bromus diandrus) is an introduced species (from the Mediterranean). In Hubbard's Grasses he says it occurs only in the southern UK, but the current BSBI map shows it well established in NE Yorkshire.  The basic visual difference from the ubiquitous Barren Brome is the length of the awns on the lemmas: up to 5 cm whereas Barren Brome rarely exceeds 3 cm. Both species have hairs on the fruit (pointing in the same direction as the awn), but they are much more noticeable on B. diandrus. These innocent-seeming hairs cause the mature seed to work its way into the soft parts of animals (paws, eyes, mouth-parts), and has led to it becoming known as Ripgut Brome, a name that was apparently once admired by Paul Auster.

We're off to Spain for a couple of weeks. I may not be blogging much, or even at all. But we'll see.

Sheep field with clouds of Wavy Hair-grass (Deschampsia cespitosa)

Byland Abbey

Returning to Kilburn



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