Wednesday, 11 February 2015

Another Ditrichum gracile population in a forestry road verge

 Ditrichum gracile  in calcareous gravel of forestry road verge

After Barry's description of the calcicole community on the west side of Mynydd Aberdare, I commented on the occurrence of Ditrichum gracile as a 'nice record for a forestry road verge'. Well, here it is again in a gravelly verge in a very similar community in Japanese Larch plantation near Banwen.

Ditrichum gracile (Banwen) with long silky leaves

The community also included Didymodon ferrugineus, D. fallax, Ctenidium molluscum and Trichostomum crispulum. Other calcicoles that occur in similar verges elsewhere in NPT include Campyliadelphus chrysophyllus, Distichium inclinatum, Encalypta streptocarpa and Jungermannia atrovirens.
The Ditrichum here forms dense turfs in places, so I looked at it closely, particularly in view of recent postings. The occurrence of an obvious tomentum (relatively dense on some shoots) encouraged me to take some specimens back for closer inspection.

 Rhizoids on lower part of D. gracile stem

However, leaf length and general morphology clearly point to gracile, as does the absence of short-leaved, deciduous branches (see Sam's post on 30/1/15). Also, when dry, the long leaves become distinctly flexuose and twist around each other at the tip. This may be a much more reliable character for gracile than the density of the tomentum, which looks like a  more plastic, phenotypic character.

Dry, flexuose and twisted leaves of D. gracile

But this also lends weight to Sam's comments regarding the occurrence of intermediate forms and safety of the split between gracile and flexicaule

1 comment:

  1. A nice addition to the calcifuge-dominated flora of NPT. The bryo-flora of forest tracks and their verges really is quite noteworthy and it's great we're getting a better understanding of these in our area. The total 'resource' in NPT must be considerable!