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         Introduction to
Moss ID Links ID1 (Intro to Plants) ID2 (Bryophytes) ID3 (Life Cycle) ID4 (Divsions) ID5 (Books & Gear) ID6 (Leaves) ID7 (Cells) ID8 (Sporophytes) ID9 (peculiar Sphagnum) ID10 (peculiar Atrichum) ID11 (peculiar Fissidens) ID12. (Key Overview) ID13 (Platygyrium start) ID14 (Platygyrium finish) ID15 (Funaria start) ID16 (Funaria finish) ID17 (Orthotrichum start) ID18 (Orthotrichum finish) ID19 (OH Atlas & FQAI) ID20. (Plag. cusp.) ID21 (Ambl. vari., Anom. Atte.) ID22 (Plat. repe., Ento. sedu.) ID23 (Cera. purp., Anom. rost.) ID24 (Clim. amer., Thui. deli.) ID25 (Atri angu.) |
INTRODUCTION TO MOSS IDENTIFICATION
17. Brick wall moss.  This little brick retaining wall is moss-covered. Substrate can be a clue for identifcation, but it isn't as hard-and-fast as the books might make it seem. There are trees nearby that might serve as sources of spores to maintain populations of normally corticolous (bark-inhabiting) species on lithic (rock) substrates. It helps to keep an open mind when keying out plants. As in the Platygyrium and Funaria examples, we'll use the key in Howard Crum's 2004 book, Mosses of the Great Lakes Forest, 4th ed. (The University of Michigan Herbarium. Ann Arbor, Michigan) to figure it out. Again, for simplicity we'll skip a few steps of the key. Here's the mystery moss. It has short upright stems standing side-by-side with sporophytes emerging from their tips, i.e., it is an acrocarp.  The moss is an acrocarp.
As usual, cell surface is an important
character. Sometimes it's not easy to tell at a glance whether cells
are papillose. Chlorplasts within the cell can give it a lumpy
apearance, and it can be hard to tell if the shapes you see are pointed
upwards. Switching to high power and slowly focussing down helps
detect surface projections, as the extremely shallow depth of field
shows peaks in sharp focus before the remainder of the cell beomes
sharp.
 In this moss the cells are pluripapillose, but with a just a few papillae per cell. Alar cells are located at the lower outer corners of the leaf, near where the leaf edge connects to the stem. In some mosses alar cells are different than the other leaf cells; they might be larger (possibly even inflated) or segregated into discrete thick-walled groups.  Here the alar cells are not differentiated in any way.
The overall growth form of a moss can be
useful in identification, including sporophyte characters. (Note
that for simplicity/brevity only one lead of couplet 40 is shown.) Most
moss peristomes have two circular sets of teeth: an outer exostome and and inner endostome. When only one set is present, it is the exostome.
 Although this moss is so abundant that it seems to form nearly a
continuous covering on portions of the wall, it nonetheless occurs in
tufts. And the seta is so short that the capsules are partly enveloped by
the uppermost leaves, i.e., the capsule are immersed. The peristome indeed seems to be in a single series.
Next: Finish keying the brick wall moss.
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