Identifying grasses. It’s obviously a Brome, but which Brome is it ? First, we need to identify the genus (i.e. is it Bromus, or Bromopsis, or Anisantha or Ceratochloa ?). This is the lower half of Key H on p. 1033.
#6 Are the lemmas strongly keeled on the back (left) or not (right). Definitely not keeled, so on to #7
#7 Always a tricky one. Annual or perennial? Look at the roots and check for the absence of rhizomes. See if there are any non-flowering shoots. No rhizomes and no sterile shoots, so annual is the best bet. On to #10.
#10 Easy one to finish with, once you realise what the question is asking. Spikelets straight-sided, widening towards their tips (distally) (left) or spikelets ovate, narrowed towards the tip (right). Read this again, until the penny drops. Ovate and narrowed, so Bromus.
The key to the 10 UK species in the genus Bromus is on p. 1088. You need to know that caryopsis means grass fruit (lemma and with the ovary inside). #1 This question always stumps beginners, often so traumatically that they just give up. Let's go through it one phrase at a time.
We are looking face-on at the back of the palea. On the left, the lemma margins are wrapped around the caryopsis; on the right they are not. Ours are wrapped around (left).
The next part of the dichotomy is about the degree of overlap of adjacent lemmas on the rhachilla (the flower stalk). On the left you can see the rhachilla between the lowest of the lemmas, but not on the right (all the lemma bases are overlapped). Our plant is on the left.
The last part of the dichotomy is the trickiest. "Rhachilla disarticulating tardily" or "Rhachilla disarticulating readily". How on earth do we know the answer to that? Try to pull the lemmas apart using your fine-nosed tweezers. Hard or easy? Ours were hard to pull apart.
Wrap-around lemmas, visible rhachis and tardy break-up mean #2 rather than #3. Now it's easy. Spikelets big (12-20mm) or small (8-12mm). Ours are 15.5mm so we have Bromus secalinus (Rye Brome). It's an annual weed of arable field margins (killed by herbicides elsewhere).
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This is what Ashurst looks like in a ‘ragwort year’. There are more than 10 flowering individuals per square metre.
This is what Ashurst looks like this year (1 August 2023). There’s not a single ragwort plant in sight.
So what is going on ? Between 1980 and 2019 ragwort numbers fluctuated dramatically but there were no extended periods of very low plant densities (less than 1 m-2). Since 2020 we’ve seen 4 consecutive years with exceptionally low numbers.
Identifying rushes. The three annual species of Section Tenageia can be tricky to tell apart. The common species is Juncus bufonius (left) and the two rarer species are J. foliosus (upper right) and J. ranarius (lower right).
They all have flat or inrolled bifacial (grass-like) leaves on the stem (the basal leaves are typically withered by flowering time). The diffuse panicle is interspersed with leaf-like bracts and each flower has 2 small bracteoles.
Juncus foliosus is the easiest to identify: its leaves are more than 1.5mm wide (left) and the seeds have longitudinal ridges (x20, right A).
Identifying rushes. The reason why our 31 Juncus spp. are so tricky to identify is that the genus is so complicated botanically. It’s worth starting by looking at each of the 10 Sections that are represented in UK, just so that you can see the issues involved.
Seaside Grass Quiz. This is arranged by habitat (sand-dune, dune slack, rocks & shingle, cliff and tidal mud-flat) then by plant size within habitat (big, medium, small). Answers tomorrow.
Grass revision quiz. Waterside and wetland grasses. The are just 10 species in this quiz, reflecting the ecological fact that rushes, sedges and other Cyperaceae are more numerous than grasses in this habitat.
Grass revision quiz. Roadside, railway and waste ground grasses. There is only one properly droopy species in this list (the rest are upright) divided into 3 categories by the height of the flowering stem (tall (>1m), medium (30cm-99cm) and short (less than30cm) ). Answers later.