A blog posting from several months ago announced our intention to revise the development under 583–584 to adopt APG III as the basis for the DDC’s treatment of flowering plants (angiosperms) and directed interested parties to a draft outlining the specific changes proposed, available on the discussion paper page of the Dewey web site.
As we invite final comments (due by 31 January 2016), we would like to share our response to several significant, and related, issues raised by earlier commenters:
- APG III has been updated on the Angiosperm Phylogeny Website (APWeb)
- APG IV is in preparation for publication
- The taxonomic hierarchy in Catalogue of Life is possibly a “best fit [among biological taxonomies] to many other data sources”
We have not been slavish in our adoption of APG III and have, in fact, already incorporated some of the changes seen on APWeb. Our plans are to confirm our organizational structure with APWeb before publication and make any adjustments necessary to represent established APG III thinking. Since the DDC treatment of angiosperms does not go below the family level, we anticipate, however, that most ongoing changes on APWeb will not affect the development of angiosperms in the DDC.
It appears that the most significant differences between APG III and APG IV will be a matter of lumping and splitting. Our proposal already does some lumping of APG families, based on literary warrant. If supported by literary warrant, splitting can be accommodated easily through expansion. As a bibliographic classification, the DDC would probably never mirror APG III or any other source exactly; at the same time, the expressive hierarchical notation of the DDC facilitates representing changing consensus on lumping and splitting decisions.
A brief exploration of the Catalogue of Life’s treatment of angiosperms provided for under 583 Magnoliopsida (Dicotyledons) revealed a structure that coincides significantly with APG III at the level of orders and families. The single biggest set of discrepancies involves the split of 1 APG III order into 2 Catalogue of Life orders. We will investigate the few discrepancies that exist between the Catalogue of Life and APG III structure of orders and families and may make changes accordingly. At the same time, the Catalogue of Life lacks taxonomic groupings between classes and orders (e.g., core eudicots, asterids), and has no taxonomically-based linear sequence among taxonomic units, both of which play prominent roles in the DDC’s development of angiosperms. While the Catalogue of Life can be useful to us, we don’t see it replacing the various editions of the APG classification for us.
After making any adjustments noted above and publishing these changes to WebDewey, we expect to revisit angiosperms on a periodic basis (perhaps every 5 years) to determine if the DDC needs to change to reflect expert opinion as captured in the latest APG edition, APWeb, and Catalogue of Life.