Wednesday, 14 January 2015

Lejeunea query

Not having a copy of Paton is a pain when it comes to those liverworts that need checking microscopically. I collected this Lejeunea yesterday from acidic sandstone rocks alongside a wooded hillside stream above Treforest (ST09V), growing near R. aciculare and S. plumosum. Most leaves have only a few oil bodies but some towards the base of the shoot (first photo) have 10+, but I think it must be lamacerina or patens. The lobules are fairly big and the angle between lobule and main lobe looks quite acute, so I wondered if this might be patens?

 Thanks as always for any help.


  1. The angles between lobes and lobules look very obtuse to me George (particularly in photo 3) and the number of oil bodies are more in the normal range for lamacerina, which is what I think it is.

  2. Thanks Charles, that seemed the most likely based on the habitat, but a few of the angles seemed quite acute (not really apparent in the photos). What is the usual range of oil body numbers in patens?

  3. There is significant overlap which I think decreases the diagnostic value of oil body numbers for separating lamacerina and patens. Jean Paton gives a normal range of 2 - 14 oil bodies per cell for lamacerina (but can be up to 20), which covers the range you are seeing. For patens the range is 2 - 8 (up to 11). However, oil body numbers in these ranges clearly separate these 2 species from cavifolia, which has cells packed with them(25+).

  4. I agree with Charles that this is L lamacerina: it certainly isn't L cavifolia as that has abundant tiny oil bodies, and most of the angles do look obtuse.

    Jean Paton's Flora has just been reprinted in paperback. It's £80 so not cheap, but it's a monumentally good book!

  5. Thanks both, I'll record it as lamacerina.

    Funnily enough I only noticed earlier on today that Paton has been reprinted recently. I think I'll just have to bite the bullet and add another tome to our overflowing bookshelves.