Comparing Scapania Species in Coastal PNW

Scapania is like the Sphagnum or liverworts--instantly recognizable to genus but then agonizing to go beyond that point. The unequally bilobed leaves with their ovate-reniform lobes are an instantly recognizable feature. There are about a dozen species in coastal BC, many clustered in subalpine habitats. I will try to add more to this table as I am able to dig up records. Using a combination of habitat and leaf features, it is possible to get to species. It turns out the shape, relative size and attachment of the characteristically unequal leaf lobes is the key to figuring this genus out. Three words from this table should be off-putting so I will explain them up front: Dorsal lobe refers to the overlapping part of the lateral leaf that you see on top when you look down at Scapania from above. It is generally smaller than the underlying ventral lobe, which is most visible and prominent when looking at the underside of the shoots. Ventral leaf decurrency refers to the way the leaf is attached to the underside of the lobe. Instead of attaching transversely across the stem, a decurrent leaf runs down along the edge of the stem for a while. This great photo by Richard Droker shows the ventral side (on the left) next to the dorsal side (on the right) of Scapania bolanderi. You can see that the leaf margin begins to parallel and descend along the stem. It is "decurrent".

Each species below is linked to an iNaturalist observation that attempts to demonstrate the features in this table. If you want to get very deep in to Scapania, try the provisional Bryophyte Flora of North America Key to Scapania (link to pdf treatment of all species of family Scapaniaceae in North America north of Mexico).

Species Habitat Teeth Keel Dorsal Lobe: Ventral Lobe (length ratio) Lobe shape Ventral Leaf Decurrency Other features
S. bolanderi Trees, Logs, Stumps, DOM Coarse Straight ~.75 round-reniform Present Dominant species in low elevation coniferous forests
S. americana Rocks and Mineral Soil Coarse Straight ~.5 round-reniform Absent Frequently deep red
S. paludosa Subalpine meadows,  hygrophytic present or absent Arched ~.65 reniform Absent very short keel
S. undulata along drainage on soil, rocks and DOM present or absent Straight ~.75 round-reniform Absent Lobes tightly appressed, often purplish
S. umbrosa Logs (often on the wood) Coarse Straight ~.5 triangular-round Present very small plant, Pointed lobe apices
S. gymnostomophila Limestone near drainage absent Weakly arched ~.3 Ovate-oblong Present giant oil bodies 1/cell
S. uliginosa Subalpine meadows absent weakly arched ~.7 ear-shaped Present Plants "scorched", blackish
S.obscura Seeping subalpine/alpine humusy soil absent straight ~.75 Ovate-oblong Absent
S. subalpina Sand and rocks, predominantly subalpine minute straight ~.9 Ovate Present Lobes seemingly equal
S.scandica Sandy soil absent ? ~.75 triangular-ovate Present
S. mucronata Rock, Soil over rock absent ? ~.5 ovate Present
Publicado el enero 17, 2023 11:14 TARDE por rambryum rambryum

Comentarios

Publicado por rambryum hace más de 1 año

What is "DOM"?

Publicado por stewartwechsler hace más de 1 año

@stewartwechsler DOM= Decaying Organic Matter. Pardon me-- my own mental shorthand bleeds out.

Publicado por rambryum hace más de 1 año

Thanks! It's easy to slip into using our own shorthands without remembering that our audience might not know it!

Publicado por stewartwechsler hace más de 1 año

Wonderful post!

Publicado por mattunitis hace más de 1 año

Excellent work @rambryum ! —Thanks for this

Publicado por chlorophilia hace más de 1 año

thanks!

Publicado por iancruickshank hace más de 1 año

Another great post, thanks! Time to find some of these and fill in those question marks.

Publicado por bradenjudson hace más de 1 año

@bradenjudson the one to hunt down at this time of year (no access to the subalpine) is Scapania umbrosa. I don't see it often, but when i do it tends to be on fallen logs across creeks and seasonal drainage.

Publicado por rambryum hace más de 1 año

Thanks @rambyum, this is great!

Publicado por johndreynolds hace más de 1 año

link is broken to the Richard Droker photo?

Publicado por doviende hace más de 1 año

@doviende I have fixed it. Thanks for pointing out.

Publicado por rambryum hace más de 1 año

I recommend actually linking to the exact photo like this: https://www.inaturalist.org/photos/2655288
because currently it's linking to the taxon page, but that might change in future to feature a different photo.

Publicado por doviende hace más de 1 año

@doviende --fixed again

Publicado por rambryum hace más de 1 año

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