What is a binomial? What is a forma? 



T. D. A. COCKERELL 



In the excellent revision of Halenia, by Dr. Caroline K. 

 Allen, lately published by the Missouri Botanical Garden, I find 

 the names Halenia Mayeri Johannis and H. taruga gasso. These, 

 from Gilg. 1916, are given without protest or comment; they 

 represent valid species from Ecuador. Such names are neither 

 binomials nor trinomials, and it seems to me that if any one 

 cared to propose entirely new names for these plants, such 

 names would be valid. However, we may better stretch a point 

 and assume that the use of the hyphen was implied, calling the 

 plants Halenia meyeri- johannis and H. taruga-gasso respectively. 

 Another question raised by the Halenia revision has to do with 

 the use of the term "forma." Botanists transfer plants from the 

 status of "varieties" to "forma," and call the result a "new 

 combination." But actually the conceptions underlying the use 

 of these terms are vague and confused. Halenia plantaginea f. 

 grandiflora has large flowers, and it is said of it that it "appears 

 to be only a variation, due merely to habitat, moisture or some 

 nutritional factor." Whether this is the case, may perhaps be 

 doubted, but if so this "forma" is quite different biologically 

 from such a thing as a "forma albiflora" of any species, which 

 is a mutation existing under the same conditions as the type 

 form. Itwould clarify the subjecttouse the term mutation (mut.), 

 but probably "forma" is now so well established that it must 

 be retained. Peculiarities due entirely to environmental condi- 

 tions acting on the individual plant really have no taxonomic 

 basis, but sometimes it may be practically useful to refer to 

 them by name. In such cases, perhaps the term phase (ph.) 

 would be acceptable. When the plants from a special environ- 

 ment all show some special features, it is no doubt best to treat 

 the segregates as subspecies, in spite of the possibility that some 

 future experiments may show them to be nothing more than 

 phases due to conditions of life. Sometimes, however, known 

 analogies are sufficiently convincing to determine the treat- 

 ment. 



Boulder, Colo. 



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