86 C. J. HUMPHRIES 



ancestry (see p. 102 for discussion). In taxonomic terms, taxa of the same age, whether these be 

 large or small groups, should have the same taxonomic rank. To complete such an ideal for the 

 flowering plants is an awesome task, since the greatest percentage of generic names apply to 

 either paraphyletic or polyphyletic groups (see p. 102 for discussion). 



Anacyclus, in fact, was originally conceived as a paraphyletic group, but was later to contain 

 polyphyletic elements (see p. 137 for excluded species). The circumscription of Anacyclus in this 

 revision has been established according to the principles of Hennig (1965, 1966), details of which 

 are given in the phylogenetic section (p. 102). Consequently, Anacyclus is defined on characters 

 unique to those species included within the genus, as assessed by comparison with the sister group 

 Leucocyclus and many other species of closely related but less easily definable genera of the 

 northern Hemisphere Anthemideae. 



It is believed that this cladistic approach to phylogenetic systematics provides the most suitable 

 biological reference system for handling species relationships. The methods of Hennig (1965, 

 1966), as practised by many zoologists such as Brundin (1972) and Cracraft (1974), currently 

 provide the most reliable cladistic techniques compatible with the concept of neo-Darwinism 

 and with Darwin's theory of evolution by natural selection (Darwin, 1859). Consequently, it 

 provides a natural classification in the sense that it reveals groups derived by common descent, 

 rather than creates them artificially as is the case with essentialist or nominalist classifications 

 based on general resemblance. 



The species is a population concept based on a combination of marked discontinuities and, to 

 some extent, crossing behaviour. All species of Anacyclus are easily defined and in several cases 

 exhibit vicarious distribution patterns as a result of allopatric speciation. In the widespread 

 annuals, however, vicariant patterns have been obscured as a result of migration into disturbed 

 habitats. The subspecies concept has been used mainly in the sense of Du Rietz (1930) to define 

 quantitatively distinctive populations with allopatric patterns of distribution. The term variety 

 has been used to define ecological variants or locally deviating populations of a species. 



Historical outline 



This survey is a chronological account of contributions to the knowledge of Anacyclus, giving 

 details of various changing generic and specific taxonomic concepts in the principal works from 

 1700 up to the present day. The taxonomic history of Anacyclus clearly mirrors the changing 

 attitudes and fashions in the subject as marked by the contributions of the significant authors of 

 the systematic tradition. To mark these changes the historical survey of Anacyclus is considered in 

 four main phases: (1) from its recognizable inception as a taxonomic entity in 1700 until the 

 publication of Linnaeus's Species Plantarum in 1753; (2) the contributions from the time of 

 Linnaeus until the major contributions of perhaps the two greatest synantherologists in the post- 

 Linnean era, Cassini and Lessing in the 1830s; (3) the expansive developments of De Candolle in 

 the same period up to the age of the great compilations of Bentham & Hooker and Engler & 

 Prantl in the latter half of the nineteenth century; (4) the contributions from the post-Darwinian 

 era until the present day. 



(1) The first adequate description of an Anacyclus species is to be found in Joseph Pitton 

 Tournefort's Institutiones Rei Herbariae (1700), where 'Cotula flore luteo nudo' refers to Chrys- 

 anthemum valentinum in C. de L'Ecluse's Rariorum Plantarum Historia: 332 (1610). Tournefort 

 did not invent the name Anacyclus but made the Valencian daisy the principal element of his 

 genus Cotula. Cotula was based on a narrow, but extremely clear concept in the sense that the 

 principal diagnostic features were well indicated. The description of the genus on page 495 in 

 volume 1 of Institutiones Rei Herbariae is clearly illustrated in fig. 282 of volume 3 of the same 

 work (Tournefort, 1700). On the evidence of this illustration and, particularly, the note on yellow 

 ligules, the winged compressed obconical cypselas of the rays and the diminutive fruits of the 

 central disc florets, there seems to be little doubt that the generic description and the first two 

 phrase names of the four included species equate with the species currently called Anacyclus 

 radiatus Lois. Despite such clarity, subsequent authors, as pointed out by Cassini (1825), com- 

 pletely ignored Tournefort's original concept of Cotula by not using the yellow-liguled Valencian 



