I collected just one inflorescence from this one. It is another brush of awns, somewhat like B. madritensis in the previous study, but with longer awns.
That resemblance is just superficial It is quite different under the microscope. Unlike B. madritensis, the glumes themselves have long awns. There are also four bristles at each node subtending the spikelet. The inflorescence itself is a spike (or raceme), not a panicle.
A candidate after a quick scan through the photos in the California manual is Elymus caput-medusae or "Medusa head". Elymus is indeed a spike. This plant may have a new name: Taeniatherum caput-medusae. The Jepson guide notes this new name, but keeps it in Elymus. It is the only annual in the Elymus genus. Another invasive species -- I still haven't found a native grass!
My awns are 50mm (5-80mm is allowed). Using the description in the Jepson guide. I have not found it, or what it used to be called in Arizona Flora. Only the lower floret in a spikelet is fertile, upper ones are vestigal (I noted most spikelets had only one floret, but some seemed to have two). There are two florets at each node, along with a pair of bristles with each floret.
Interestingly, now that my sample has been sitting on the table most of the day and drying out, the awns, which were originally parallel to the culm and now almost all reflexed and sticking out perpendicuTaeniatherumlar to it.
So let's try running the keys in the California field guide. Elymus is in "Group 17".
Bypassing a number of special case questions gets us to 6, which is whether we have only 1 or 2 spikelets per inflorescence, or whether we have "few to many". We have many, so on to question 8. More special questions and we get to 12 which asks if spikelets are subtended by awns or hairs (they are!) This takes us to Group 5. (Note that we are not heading to Elymus in Group 17!!)
Now for the group 5 key. Are the spikelets subtended by silky hairs or stiff bristles. We have bristles - on to question 4. Are the bristles persistent or do they fall with the spikelets? I think they are persistent -- are they glabrous or are they conspicuously hairy? They are glabrous. The last question: is the ligule present or absent? I see a tiny membrane, so I say it is present. This takes us to Setaria, but this does not seem right. The spikelets are supposed to be awnless, but these clearly have awns. The pictures don't look right either. I liked Elymus much better.
So where did I go wrong? Clearly I was misled by question 12 that asked about awns subtending the spikelet. I must be misinterpreting the structures. I am going to put this aside for now since I have invested a huge amount of time on it, presumably learning something, and will press on with a couple of other plants I collected. Maybe a year from now I will return to this and it will all make sense.
Hordelymus caput-medusae (L.) Pignatti Hordeum caput-medusae (L.) Coss. & Durieu Hordeum intermedium (M.Bieb.) Hausskn. Taeniatherum asperum (Simonk.) Nevski Taeniatherum crinitum var. caput-medusae (L.) J.K.WipffSo there are some starting points. These turn up nothing in Arizona Flora, and I even leaf through all of the grass family entries (which is worth doing just for general familiarization) but come up empty doing this. Buffel grass is not in Arizona Flora either, so maybe there is some bias against invasives, or a forlorn hope that they won't persist. No luck in the Colorado flora either for any of these. Let's dig deeper using some online resources: According to TNRS, the current accepted name for Elymus caput-medusae is Cenchrus biflorus! Now there is a surprise, and the plant looks nothing like what I have. Submitting Taeniatherum caput-medusae simply indicates that this is a valid name, at least at this point in time, but stay tuned. No list of synonyms, which is what I am really after, how else can you search the existing literature? Searching Tropicos for Elymus caput-medusae indicates that it is a legitimate name and yields no list of synomyms.
So I am still looking for a good online resource to find plant name synonyms.
Tom's Plant pages / tom@mmto.org