SPJUT, RICHARD W. World Botanical Associates, P. O. Box 2829, Laurel, MD 20709-0829. - A revised taxonomic key to the species and varieties of Taxus (Taxaceae).
An earlier attempt to identify characteristics of Taxus that
fit into a phytogeographical species concept, as recognized by Pilger,
Rehder and others, has not proved satisfactory for 8-12 species that
have been generally recognized in the genus. An alternative approach
has been to classify morphological features of Taxus without
regard to their geographical parameters. Leaf anatomical data suggest
a long evolutionary history for the genus, whereas morphological
differences in reproductive structures are rarely evident. Generally,
species are recognized in three groups with further subdivisions based
on leaf anatomical features. These are the Wallichiana Group
that includes a Chinensis Subgroup, a Sumatrana Group,
and a Baccata Group with T. canadensis and T.
cuspidata species alliances or complexes. Currently, about 55
taxa are recognized, many of which are sympatric or allopatric in
distribution, and many hybrids or intermediates are also evident.
Examples of the key will be posted. It will also be placed online
(www.worldbotanical.com). The key includes more than 100 photographs
and illustrations to show comparative examples of the same taxon from
different geographic regions. Included are many type specimens. The
similarity of taxa from distant geographic regions and their
dissimilarity within a geographical area demonstrate that the
taxonomic characters applied in the present study are more meaningful
than the past arbitrary phytogeographic species concepts of the genus.
Nomenclatural references, descriptions, and citations of specimens
will be made available in a separate publication on a taxonomic
revision of the genus.
Key words: conifers, gymnosperms, Taxaceae, taxonomic key, Taxus