Monday, 2 March 2015

Tortella torment

Cliffs at Penmaen overlooking Threecliffs Bay
where all of Glamorgan's four Tortella species grow
Below left: Tortella sp. growing with Pleurochaete squarrosa (in centre of the image) becoming crisped. Below right: T. flavovirens sample collection point.
My records show the Nationally Scarce Tortella inclinata was first recorded in the Penmaen-Threecliffs area by Sam in 2010, who subsequently found it to be locally abundant on a section of cliff slope with scattered patches elsewhere in the vicinity. Although I recorded it nearby last year for my first time, the collection was more fortuitous than anything else and in an attempt to learn the field appearance of this species, yesterday, I took a few images and collected a sample of what I thought was probably inclinata growing abundantly on a sandy cliff slope about 100m east of Sam’s large colony. Under the microscope it was clear I was wrong as the costa on the adaxial side was covered by quadrate cells (except the third near the base). Furthermore, the leaves became highly crisped upon drying so unfortunately all I'd photographed and collected was flavovirens. [At least that's what I thought! After making this post I found a second sample I'd left in my coat pocket, which I was convinced at the time was probably inclinata; to my relief this turned out to be the case. Which species is represented in the general shot above alongside the Pleurochaete I'm now not sure as there's not really enough detail in the image. The difference between the two species using a lens is in fact rather striking when they are side-by-side, the shoots of inclinata being larger and more erect, with a stronger nerve appearing more prominent in a more boat-shaped leaf apex, reminiscent of Trichostomum crispulum]. Plants showing these characters were widespread on the cliff I looked at, but it's interesting that both species grow mixed in together.
Tortella flavovirens
Tortella inclinata
T. flavovirens foreground, T. inclinata behind
After reading Smith I'm now wondering how similar the resemblance is between flavovirens and the short-leaved form of tortuosa and if there is a safe way of separating the two, as he only mentions the degree of crisping upon drying; this was considerable in my specimen, which might indicate tortuosa?

For interest here are the vc41 distribution maps of our four Tortella species:


  1. I'm not sure what you mean by the "short-leaved form of T. tortuosa" - that's a worry I hadn't been aware of. I generally wouldn't expect them to be confused, but Smith seems to have known something I don't. Tortella densa is another problem to throw into the mix, as that is treated in non-British Floras as like T inclinata but with leaves tapering from the base. I muddied the waters when I reported T bambergeri new to Britain by describing T densa as "spiralled like a Catherine Wheel", as I now think that's a form of T tortuosa with an atypical lack of short cells over the nerve. Finally, there's the flavovirens glareicola problem to consider, and I'm not convinced that David Holyoak's intermediates were the last word on the subject because larger-celled forms (matching glareicola) predominate in dunes whereas smaller-celled forms predominate on coastal slopes and upper saltmarsh. A very difficult genus all in all!!

  2. Clearly there are some grey areas to contend with here despite typical material of each species being fairly distinct. I guess it's a genus where retaining some vouchers might prove worthwhile.