Tuesday, 28 April 2015

Lejeunea patens (Pearl Pouncewort)

Lejeunea patens is uncommon in VC41. As far as I can tell, the most recent record was made by Sam and Graham (2010) for Sgwd Gwladys in the Pyrddin Valley, where it grows as an epiphyte on Oak. The only other records (1960s) are for Craig y Llyn, where it grows on rock. So it was nice to find these plants growing as epiphytes on willow in the conifer plantation above Pentreclwydau (between Resolven and Glyn Neath).
Lejeunea patens has a distinctive, large lobule that makes a sharp, acute angle with the leaf, which differentiates it from the much more common L. lamacerina (the most common Lejeunea in NPT).

Lejeunea cavifolia has smaller lobules, but the 2 species are best distinguished by their cellular oil bodies. While cavifolia usually has a large number (25+) of small oil bodies, patens has few (up to 8) and they are larger.

The colonies have a distinct pale lustre in certain light, so the common name is rather apt.


  1. Very nice! This species is locally abundant alongside Colura on willows in the humid coniferised valleys of Brechfa Forest, so I'd expect there to be further populations in the Glamorgan Valleys.

  2. Lovely, a species I've yet to see.

    Regarding lamacerina, I've seen it a few times recently in slightly unlikely epiphitic situations, i.e. not very humid sites. The most surprising was an Ash trunk on an arable field margin. I've checked oil bodies in all cases and all were clearly lamacerina not cavifolia (or patens).

  3. Very nice images as always Charles, plus a good record. My recent Lejeuna query from Paviland coast turned out to be patens (det. by Nick Hodgetts) - maritime calcareous grassland possibly being a little bit of bit of an anomaly?

  4. Sorry Barry, I didn't realise that your Paviland Lejeunea had been resolved. I thought the issue there was lamacerina versus mandonii. Both of those species have obtuse angles between lobules and leaves, which is what appears to be the case with most of leaves in the photo of your specimen. I'm intrigued. Why is it Lejeunea patens?