An Introduction to the Bryophytes of British Columbia

by

Dr. Wilf Schofield, University of British Columbia Herbarium

“Bryophytes” is a term of convenience that includes mosses, liverworts and hornworts.  The mosses encompass several evolutionary lines:  peat mosses (Sphagnopsida), valved mosses (Andreaeopsida), puzzle mosses (Takakiopsida) and “true” mosses (Bryopsida).  Sometimes the hair-cap mosses (Polytrichopsida) are separated as an evolutionary line independent of the true mosses.  The liverworts (hepatics) encompass two distinctive evolutionary lines: the Jungermanniopsida (predominantly leafy, but also some thallose liverworts) and Marchantiopsida (complex chambered thallose liverworts).  The hornworts (Anthocerotopsida) are usually treated as a very distant evolutionary line. All of these evolutionary lines are present in British Columbia.

A simple definition of “bryophytes” denotes a green plant in which the sexual generation (gametophyte) is usually perennial and the sporophyte is largely dependent on the gametophyte for its survival and maturation.  In bryophytes, the sporophyte produces a single sporangium while the gametophyte may bear several sporophytes.  Sex organs are antheridia that produce motile sperms and archegonia in which each produces a single non-motile egg.  Liquid water is necessary for fertilization.

In bryophytes, the mature gametophyte is generally leafy, but can be strap-shaped, or thallose.  In most gametophytes, growth is indeterminate.  Neither gametophyte nor sporophyte has a complex vascular system that is as well-developed as in the vascular plants, although they may have a system that conducts water and nutrients for growth and reproduction.

In British Columbia reasonable estimates indicate the following diversity of genera and species of bryophytes:

Genera Species

Sphagnopsida                          1                                  45 

Andreaeopsida                         2                                  11 

Takakiopsida                            1                                  1 

Bryopsida                     ca.        200                  ca.        663

Jungermanniopsida        ca.        56                    ca.        213

Marchantiopsida                       15                                22

Anthoceropsida                        2                                  3

This means that British Columbia possesses the richest diversity of any political division in Canada.  It is also greater than the combined bryoflora of all of the United States west of the Rocky Mountains.  This diversity is the result of the considerable environmental diversity of the province, combined with the historical circumstances that led to the assemblage of floristic elements from adjacent areas as well as the survivors of elements of pre-glacial time.

Identification of bryophytes involves the utilization of microscopic features.  This increases the number of characters for discrimination.  With experience, it is possible to recognize most genera and many species based on features visible in the field. However, for confirmation of identification, recourse to a microscope is necessary for many species.

Bryophytes, as with all other organisms, show some polymorphism, and this is often exaggerated in extreme environments.  The variability is greatest in the gametophyte.  Poorly developed specimens often mimic similar species and genera, therefore caution is necessary in applying names.

Collecting bryophytes is relatively simple.  Rules to be followed include the collection of a reasonable specimen, cleaning the specimen before drying, and in the case of liverworts, recording details of some microscopic features from the fresh material where these features disappear in dried specimens (e.g. colour, oil body number and form per cell, thallus anatomy).  Details of the habitat can contribute features useful in determination (e.g. epiphytic, on rock, and kind of rock, soil, in water, etc.). 

Specimens are air-dried (not pressed) and spread so that they are easily accommodated in a packet approximately 10 cm x 14.5 cm.

Labels should record the geographic locality where the specimen was collected (including approximate latitude and longitude), elevation above sea level, nature of habitat (including general vegetation), date collection was made, and the name of the collector.  Ultimately the determination of the plant is also on the label. 

Storage of dried specimens is simple because insect damage is usually minimal, particularly when the specimen is cleaned.  Extraneous soil should be removed because this may erode the specimen each time the packet is handled, and it makes the specimens “dirty” and more difficult to determine.

Collecting specimens should always observe conservation ethics.  Never collect the entire colony of a species.  Indeed, it should not be apparent that a collection has been taken, and a “scar” left behind.  A collection, however, needs to contain enough material to be dissected while the determination is made, and sufficient should remain in the packet to document the specimen for the collector.

In British Columbia, the major collection of bryophytes is housed in the Department of Botany at the University of British Columbia. This collection is available for consultation during normal working hours.  Well-prepared and documented specimens are welcome as gifts to the herbarium, especially when they come from sites that are remote and difficult to access.

At the University of British Columbia an introductory course on bryophytes is offered each year.  Registration is limited and the course has proven to be popular for many years.

To learn bryophytes on one’s own, there are two books that have been written for amateurs, and that are designed for the British Columbia flora:

Schofield, W. B. 1992.  Some Common Mosses of British Columbia.  Royal BC Museum Handbook.  Queen’s Printer, Victoria, BC. 394 pages. Illustrated.

Schofield, W. B. 2002. Field Guide to the Liverwort Genera of Pacific North America.  Global Forest Society and University of Washington Press, Seattle.  228 pages, Illustrated.

These two books direct the serious student to more comprehensive literature.

As with all organisms in the province, bryophytes are threatened by human disturbance or destruction of the environment.  In consequence, some bryophytes are more widespread than they would be without such disturbances.  Most, however, have had their abundance restricted.  Indeed, a few have been extinguished from the provincial flora within a brief period of time.

Wilf Schofield is the Curator of the Bryophyte Collection at the University of British Columbia Herbarium.