Genera of Poaceae. Phalaris. This is a genus of big contrasts, from huge perennials like Reed Canary-grass to delicate little annuals like Canary-grass. What they have in common is that the spikelets have 3 florets but only the terminal one is bisexual (other 2 are mere scales)
As an indication of the complexities involved in differences between the species of Phalaris, the genus appears in no fewer than 3 of the generic keys in Stace. The main one is Key G, but Palaris also appears in Keys C & K as well.
Key G concerns grasses with all spikelets bisexual and similar, but within each spikelet only 1 of the florets is fully developed, with 1 or more sterile or scale-like florets. The first question is easy: is it a Setaria with stiff bristles at the base (left) or not (right)? Not.
Another easy one. Is the ligule hairy (left) or not (right). Not hairy My Lord.
Now for the serious business. Count the male or sterile florets below the bisexual floret (X10 and look very carefully for small, scale-like reduced florests). Are there 1 (left) or 2 (right) ?
Start with the 1 reduced floret. Is there an awn from the proximal half of the back of the lemma (left) or not (right) ?
Lastly, is the ligule membranous (left) or absent (right) ?
There is a membranous ligule, so this plant is Phalaris. Now for the part of the key with 2 male or sterile florets below the bisexual floret.
Measure the lengths of the two glumes. Is the lower glume half as long as the upper (left) or are the two roughly equal (right) ? They's nearly equal, so right.
Finally is the panicle diffuse (left) or compact (right) ? Easy. It's compact. Almost spike-like. So it's Phalaris.
• • •
Missing some Tweet in this thread? You can try to
force a refresh
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.
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.
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.