Mapping Species Distributions

LIVERWORTS OF BRITISH COLUMBIA

Fringed heartwort (Ricciocarpos natans), photo by Curtis Bjork.

by

Dr. Wilf B. Schofield
Curator of Bryophytes
University of British Columbia Herbarium

The liverworts of British Columbia is a work in progress.  The treatment of species in the atlas pages of E-Flora BC are preliminary and may lack information that the user would like. If so, we should be informed so that this can be addressed (within reason).  The descriptions are not intended to be detailed, but include, it is hoped, the essential information.  The distributions are undoubtedly incomplete. This reflects the collecting activity for liverworts in the province.  In consequence, the southern part of the province is better documented than the northern part.  Maps are based on material deposited in the bryophyte herbarium of the University of British Columbia, where the most comprehensive collection for BC is housed.  This probably represents the current understanding of the provincial flora accurately, but experienced collectors would undoubtedly add to the details of the distribution patterns, demonstrating that some species are more widespread than available vouchers show.  Sight records are not mapped and the identification of each specimen must be confirmed and the specimen housed in a collection accessible to scientists as well as the general public. At the moment, the most appropriate repository for vouchers is the herbarium at the University of British Columbia.

Asterella gracilis. Photo by Adolf Ceska.

For many liverworts fresh material is easier to determine than is dried dead material. This is a consequence of features that are lost with drying, for example, oil body number and structure in the cells of the leafy liverworts, and cross-sections of thallose plants where details of air chambers, oil body distribution are possible to determine in fresh material and impossible or difficult to interpret when material is rehydrated.

A rough estimate of the number of species  of liverworts in B.C. is 210. Others have been reported, but records are either doubtful or specimens cannot be traced. Undoubtedly the flora is larger, but until specimens are available and/or further field work is done, the number remains tentative.