California Moss eFlora: Introduction, Page 2

Campylopus introflexus
Campylopus introflexus
Bartramia ithyphlla
Bartramia ithyphylla
Daniel H. Norris
Daniel H. Norris
Fontinalis hypnoides, photo John C. Game
Fontinalis hypnoides
Hookeria lucens
Hookeria lucens

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This online flora is a guide to mosses in California, but the keys also include all mosses currently known from adjacent areas west of what might be called the Rocky Mountain flora. Species mentioned but unknown from California are indicated by a note, such as "not known from CA" or "known from NV just west of CA."

The "general key" is the route to a large number of "genus keys," some of which contain coverage of more than one genus in a key. The genus keys are titled something like "Key to Acaulon Etc." meaning a key to Acaulon species and the various other species that one might confuse with Acaulon. The general key, like the longer genus keys, is highly redundant and will often allow correct determination along several routes through the key. Each genus keys is preceded by a discussion of the characters used in separating species, an alphabetical listing of the species covered by that key, and some notes on taxonomic issues that might cause confusion. After keying, one proceeds to a "species page" that provides links to any pictures, descriptions, and specimens from California attributed to the presumptive species. The species pages also map the specimens and provide a graph of elevation x latitude.

No doubt there are a very large number of erroneous attributions and poor characterizations. Please realize many bits of information on the species pages and many specimen identifications linked from the species pages were made long before contemporary literature was published. It is our hope that by making all this information accessible scholars will spot opportunities to work hard to improve the moss flora of California.

Use of our keys requires a compound and a dissection microscope. The compound microscope should have an optical micrometer capable of measuring cell size in micrometers. When we give cell width measurements, we intend them to include the lumen and one of the lateral wall.

Dissection of a moss requires the removal of individual leaves for mounting on a microscope slide under a cover slip. Most dissection can be accomplished with a straight dissection needle, a fine-point forceps, and a box of razor blades. The stem is often held by the needle in place on a slide after wetting, and one point of the forceps is used to scrape the leaves off. Mosses with easily fragmented leaves can be prepared by holding the leafy stem in place with the dissection needle and scraping with the razor blade. Mosses with very decurrent leaves should be held in place with a needle and then one should use the forceps to pluck leaves from the stem.

Identification of many mosses requires cross-sectioning of leaves. That can be accomplished with a straight dissection needle that is used to hold the leaf in place and a newish single-edged razor-blade. A minute chopping motion by the razor blade next to the supporting needle should cut the leaf at about its mid-length. Subsequent chops remove cross-sections that are so thin as to turn on their sides allowing full view of the cross-section through the compound microscope. Rolling the needle very slightly between chops determines the thickness of the section. With experience you will develop your own effective techniques.

Use of our keys requires careful attention to the wording. Sometimes we refer to characters not uniformly present in all individual leaves or shoots. The words "sometimes," "usually," "mostly", and "often" are placed in the key to provide for those instances.

Nearly all mosses can be identified solely on the basis of examination of the leafy plant (the gametophyte). It is also useful, and occasionally necessary, to examine features of the spore-bearing axis (the sporophyte). Through a dissection microscope one can observe features of the capsule shape and orientation, as well as seta length and calyptra morphology. One does, however, need more dissection and magnification to examine the cellular morphology of the capsule wall cells (exothecial cells), and especially those of the teeth that line the capsule mouth (peristome teeth). Preparation of a capsule for viewing requires a longitudinal razor-blade cut of the capsule with subsequent arrangement of the resulting identical halves of that capsule. Features of the exothecial cells require viewing under the compound scope of the outer surface of the median capsule wall. Features of the peristome are best viewed by orienting the two capsule halves so that each surface is exposed to view.

Keys never work perfectly. Someone just starting out with an unknown moss in hand will surely have a onerous few hours ahead of him or her. However, as you learn more and more species and genera, and what is meant by the characters that are mentioned, we believe you will find the keys to be more helpful than they were at the start. For beginners, we would suggest you try to match your mosses up with pictures in the moss section of Calphotos. With a match as a guess, see if you can trace your way through the keys backwards. This will teach you the structure of the key and some of the vocabulary.

If you are new to moss identification, we suggest you take a Jepson Workshop introducing bryophytes. These workshops provided opportunity for networking as well as getting over the first and hardest learning experience needed to identify mosses. Keys alone are inadequate.


The vocabulary of bryology diverges greatly from that of vascular plant morphology. Therefore, a glossary is an essential part of any process of learning bryophyte taxonomy:

Bill Malcom & Nancy Malcom 2000. MOSSES AND OTHER BRYOPHYTES, AN ILLUSTRATED GLOSSARY, 2ND ED. Micro-Optics Press.

Some few words or expressions appear in our keys that are absent or inadequately described in Malcolm and Malcolm (2000). We treat these in the discussions at the head of the relevant genus key. The list below allows reference to those discussions:


Growth Form:
  Plumose vs. Dendroid: see Climacium
  Plagiotropic/Orthotropic Shoots: see Plagiomnium

Leaf Lamina:
  Nematogons: see Calliergon, Hookeria
  Cuticular Papillosity: see Amphidium
  Channeled Leaves: see Didymodon
  Carinate Leaves: see Fontinalis
  Cell Corner Thickening: see Mnium
  Chlorocysts/Hyalocysts: see Sphagnum
  Postical/Antical Margin: see Schistostega

Leaf Margin:
  Crassiserrulate, Crassidentate, etc.: see Ditrichum
  Binate vs. Geminate: see Conardia

Costa Morphology:
  Hydroids: see Syntrichia
  Stereid Bands: see Campylopus

Stem Morphology:
  Brachytheciaceae Pseudoparaphyllia: see Amblystegium
  Macronematal Apparatus: see Anacolia
  Micronemata/Macronemata: see Rhizomnium
  Leaf Buttress: see Bryum
  Hyaloderm: see Hypnum, Sanionia
  Axillary Hairs: see Leptobryum
  Sexuality: see Atrichum


  Funarialean Peristome: see Entosthodon

  Funarialean Stomates: see Entosthodon

  Cryptoporous/Phaneroporous Stomates: see Orthotrichum