Colorado Flora: Eastern Slope A Field Guide to the Vascular Plants

"The completely revised edition of this outstanding guide to the fascinating plants of Colorado provides an improved means of identifying and learning about them. Based on decades of experience in the state and around the world, the authors offer unique insights and a sound basis for expanding our knowledge into the future."
– Peter H. Raven, President Emeritus, Missouri Botanical Garden, St. Louis

"Taxonomist Bill Weber and amateur taxonomist and erstwhile physicist Ron Wittmann's venerable guidebook duo to the Colorado flora is now in its fourth edition. [...]

Edition 1 is by Weber solo, whereas editions 2 to 4 are by Weber & Wittmann (for reviews of editions 1 and 2 see, respectively, A. Löve & D. Löve, Taxon 40: 159–160, and R. Schmid, Taxon 46: 158, 179–194).

All eight volumes in the four editions retain Weber's excellent, detailed, and delightfully opinionated "introduction" that is a mini-course in classical taxonomy. All eight books arrange taxa alphabetically within the three main supergroups (pteridophytes, gymnosperms, and angiosperms). The eight volumes are essentially an extended key, an initial "key to the families" preceding the supergroups. Edition 2 was the first to gang the B&W drawings at the rear. Edition 3 was an evolutionary update of edition 2. Among other things, edition 3 for cost reasons jettisoned the color photos (many of iffy quality) of editions 1 and 2.

The latest edition is an evolutionary and quasi-revolutionary update of edition 3. The changes made for edition 4 are many: a book with larger dimensions and rounded corners; front endpaper maps; the sub-subtitle A field guide to the vascular plants added to the title page, cover, and spine; a new twelve-page introductory section called "background of floristic work in Colorado"; a new one-page list of "books to inspire"; the introduction retitled "a vade mecum for the field botanist"; and, naturally, updates and refinements for the keys and taxa, including a new treatment of Botrychium by D.R. Farrar & S.J. Popovich.

Edition 4 is a quasi-revolutionary upgrade because nonagenarian author Weber has gone quasi-molecular. The authors for the latest revision "had to grapple with the problem of how and what to treat, in a field guide" (W.A. Weber, pers. comm., 6 Apr. 2012). That is, how to deal with the brave new, topsy-turvy world of phylogenetic taxonomy where things are not what they used to seem, for instance, where most scrophs are plantains, and where most plain lilies are no longer such. As Leonard Cohen said, non- taxonomically (1992): "I've seen the future, brother; it is murder."

Weber & Wittmann's solution is to call attention to the molecular work and then mostly ignore its results. Adding the subtitle A field guide to the vascular plants (incidentally, this seems to have escaped the attention of library catalogers) and retitling the introduction as "a vade mecum for the field botanist" facilitate dismissal of the molecular work. After all, the users of a guidebook want practicality, not virtual reality; they want a morphological, ecological guide to the biota, not an homage to its molecular make-up, which may lack physical distinctions. Practical users tolerate a world where paraphyly is allowed and where monophyly does not automatically trounce or trample or trump paraphyly. As F.O. Bower said (The ferns, 1923, vol. 1, p. 192): "Evolution has followed lines of opportunism, not of logic" (for "logic" substitute the modern "binary logic" or "parsimony").

The frustration that many critics have had with "the current cladistics tripe that is overwhelming [taxonomy]" is not only its inclusiveness but also its changeability. The results often derive from lab workers who mostly shun the field and are unappreciative of morphological variation. Moreover, as techniques and concepts change, cladists arrange and rearrange their molecular phylogenies (APG in 1988, APG II in 2003, APG III in 2009), seemingly debating as did the perhaps apocryphal theologians of yore about how many angels can dance on the head of a pin. Ultimately, if and when a molecular phylogeny is finalized for the angiosperms and the other supergroups, molecularists must provide a reliable nomenclator guide for their new names versus the old field names of the guidebook realists. Hopefully such a concordance will not be a "total nightmare," as already claimed for the name changes in California's phylogenetic second edition of The Jepson Manual (2012; see separate reviews by R. Schmid and E. Dean, Taxon 61: 1358–1362; see also previous review). [Disclaimer: the two phrases just quoted are not mine; I protect their source.]

Weber & Wittmann write less vehemently: "Currently, taxonomy is in a state of upheaval, largely due to [molecular] evidence introduced. ... Although we feel that it is premature to adopt the new taxonomy, lock, stock, and barrel, we often mention at least the proposed changes. In any case, professional and amateur field botanists require a practical classification scheme that is based primarily on morphology and ecology, and that de-emphasizes characters that cannot be easily observed. [...] We have attempted to bring the Colorado Flora into harmony, following the FNA [Flora of North America North of Mexico, 1993–] in some instances and noting differences of opinion in others." (p. xi Eastern/Western). Practicality thus is the guiding principle. Weber & Wittmann amplify: "We often recognize paraphyletic groups that are more realistic in a local or regional flora where identification is more significant than abstract phylogeny. We feel that the phylogenetic approach does not take into consideration the various kinds of barriers (cytological, seasonal, ecological, and morphological) that separate the generic divisions" (pp. xxv–xxvi Eastern/Western).

For example, regarding the new cladistic world where the family Scrophulariaceae is now a rump group, at least in the western United States [...], Weber & Wittmann comment: "Based on molecular evidence, this family recently has been broken up and most of its members have been moved elsewhere. Unnatural or not, the traditional Scrophulariaceae remains a useful, morphologically recognizable group, for Colorado at least, and we keep it together in deference to our amateur readers." Under Plantaginaceae they write: "Lately, much of the Scrophulariaceae has been moved into this family. For practical reasons, we prefer the traditional treatment." Thus, Weber and Wittmann keep Castilleja, Mimulus, and Penstemon in Scrophulariaceae and state: "The FNA places this genus in the Orobanchaceae"; "The FNA places this genus in the Phrymaceae"; "The FNA places this genus in the Plantaginaceae" (quotes from, respectively, pp. 358/337, 266/253, 361/340, 363/342, 365/344 Eastern/Western).

There has always been reaction to taxonomic change, of course. Two famous cases are Sequoia gigantea becoming Sequoiadendron giganteum in 1939 and Pseudotsuga taxifolia becoming nomenclaturally P. menziesii in 1950 [W.A. Dayton, 1943, The names of the giant sequoia: a discussion, Leafl. W. Bot. 3: 209–219; E.L. Little, Jr., 1952, The genus Pseudotsuga (Douglas-fir) in North America, Ibid. 6: 181–198]. However, such changes have been on a limited scale, unlike the massive realignments demanded by cladistics.

I believe Weber & Wittmann's approach, namely, stress on practicality, allowance of paraphyly, and mention of cladistic alternatives, is a perfectly acceptable approach, and in their case the only feasible approach. Converting the two-volume Colorado flora cladistically would have had the deleterious effect of requiring Weber & Wittmann to make substantial revisions not only of keys but also of circumscriptions of species, genera, and families. Colorado and California both have rich floras, California with roughly twice as many species in a 52.2% larger area. The phylogenetic second edition of The Jepson Manual (2012) was developed with an army of 332 contributors, including 6 main editors. In contrast, the fourth edition of Colorado Flora (2012) was essentially a two-man effort.

Weber & Wittmann's mentioning of molecular realignments of taxa, but not accepting them "for practical reasons," at least allows the inquisitive to seek edification with an Internet search, as for "Phrymaceae Mimulus". An alternative to Weber & Wittmann's repeated textual comments about molecular results would be to isolate molecular realignments of taxa in an appendix, as done in Proctor's 2012 revision of his flora of the Cayman Islands [...]. See also the "Considerations" commentary following.

I conclude with a few remarks about other aspects: (1) I failed to find in editions 3 and 4 of Colorado Flora an indication of how many taxa are newly added compared to the previous edition. The paragraph "some floristic statistics" has the same information in editions 2, 3, and 4: the eastern slope has 155 families and about 2300 species, only 696 on that slope; the western slope has 142 families and about 2100 species, only 517 on that slope (pp. xxxix/ xxxvii Eastern/Western, ed. 4). (2) For some reason edition 4 inconveniently places the index before the illustrated glossary rather than after it, as done by editions 2 and 3. (3) I find the small light font in edition 4 almost unreadable without a magnifying glass. Perhaps nonagenarian Weber has better eyesight than septuagenarian Schmid."

– Rudolf Schmid, University of California, Berkeley, Taxon 62(1), February 2013, 199-200