Monday, June 08, 2020

Meadow Brome (Bromus commutatus) during lockdown

Meadow Brome (Bromus commutatus). Swindon, 3 June 2020

Last Wednesday, 3 June 2020,  I set off for a not very enthusiastic walk. It had been the sunniest May since records began -- every year seems to break some kind of heat record --, but June was looking like it hoped to make up for it: a ten degree temperature drop, iron skies, and a wind that contrived to be always in my face. But then I caught sight of this.

My usual approach to short-awned bromes is simply to assume they are all Soft Brome (Bromus hordeaceus, formerly named Bromus mollis, Sw: Luddlosta). It saves a lot of trouble, and 98% of the time I'll be right, because Soft Brome, also known as Lop Grass (that's the name I myself use), is very common and very variable.

This however was one variation too far. The open panicle with each spikelet on a long pedicel gave the grass an entirely different feel (compare photo of Bromus hordeaceus at the end of this post). Besides, it was a meter tall, which would be an unusual (though not unprecedented) height for Bromus hordeaceus.

It's a rare treat to get acquainted with a new grass, especially when it's only a few hundred yards from home. Once I'd got my eye in, I realized there was plenty of it, in a straggling colony along a residential access road. Most of the individuals didn't have such open panicles as the first one I noticed, but they all had long pedicels. I took some windy photos (some good, some not so good) and later I did some reading up.

Meadow Brome (Bromus commutatus). Swindon, 3 June 2020

I'm fairly confident my grass is Meadow Brome (Bromus commutatus, Sw: Brinklosta), which is the least uncommon of the other short-awned bromes, especially in the lowlands of south-central England.

The Latin word commutatus means "changed" or "variation" and usually implies that the species in question is very similar to another one. In this case the allusion seems to be to Smooth Brome (Bromus racemosus, Sw: Ängslosta), which is similar to B. commutatus in many ways but has smaller spikelets and lemmas; perhaps they are really subspecies of the same species.

As you may know I've developed an aversion to picking plants in pursuit of my hobby, so I didn't bring any samples home with me. A couple of days later I went back with a tape measure (I used always to carry a rolled up IKEA paper tape measure, but it got lost during a recent exchange of backpacks). It's actually preferable to do the measuring on the spot, because you get a better feel for the range across the colony.

I must admit, though, that I deviated from my principles to the extent of taking home one faded spikelet. Prising apart spikelets outside on a windy day is pretty impossible; and anyway, neatly removing one spikelet for further study would probably do less harm than probing away at lots of spikelets on the living plant. I suppose this will seem like fussing about trivialities. True enough, a spikelet here or there, a haulm here or there... Grasses are well able to cope with such eventualities. But to me it's chiefly about developing a practice of reverence for nature. We see where the opposite has brought us. And besides, I'm finding it an enjoyable challenge to try to distinguish tricky groups of species, like grasses or willowherbs, without resorting to gathering samples. Now that our smartphones can take limitless photos for no cost it's become much more feasible.

Anyway, the measurements. Average spikelet length (including awns) was 2.3 cm. The lemma length (excluding awn) was 0.9 cm. That's perfect for Bromus commutatus and much too big for Bromus racemosus. I was happy to find that the measurements were also a bit too big for the rare Field Brome (Bromus arvensis, Sw: Renlosta); I didn't want to have to think about that.

I also inspected some of the ligules (the small membrane at the point where the leaf diverges from the stem, often very handy for ID) and noticed that some were torn, which Hubbard mentions in his description of B. commutatus but not the other two.

Faded spikelet of Meadow Brome (Bromus commutatus), with one glume bent back so I could measure the length of the lemma. Swindon, gathered on 5 June 2020.

Meadow Brome (Bromus commutatus) with the anthers showing. Swindon, 3 June 2020

Meadow Brome (Bromus commutatus). Swindon, 3 June 2020

I wondered why I never noticed this colony last summer, when I would have walked past it most days. Most likely it was plain stupidity, but another factor might have been council mowing, which has been much reduced under lockdown, meaning that 2020 is a great year for looking at grasses.

But writing that breezy sentence I feel a sudden twinge of unease. John Harris reminds us that lockdown has already brought significant hardship to some of those parts of Britain that are perpetually under-reported. The harvest of poverty and unemployment will be a sorry one. And everywhere the lonely and vulnerable have had an added burden to contend with. Unanswered fears become amplified. In their own homes and in care homes, many have been lost not to COVID-19 but to a neglect they can't always understand. The grass is flourishing in the midst of a social tragedy.

Meadow Brome (Bromus commutatus). Swindon, 3 June 2020

Soft Brome or Lop Grass (Bromus hordeaceus). Swindon, 3 June 2020

Photo of Soft Brome, for comparison. The pedicels are so short, only 2-8 mm, that the spikelets cling to the main stem rather than hanging off it.

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