108 C. J. HUMPHRIES 



Little more will be said about Leucocyclus, except to say that it is the sister-group of Anacyclus 

 in the sense that it forms the second dichotomy in the cladogram (Fig. 10 B). Should this be the 

 correct interpretation, then it follows that character states shared by Leucocyclus and the two 

 Turkish Anacyclus species A. nigellifolius and A. latealatus (character 36) must be interpreted as 

 independently derived to give the most parsimonious explanation of the data. 



The most distinctive taxon within Anacyclus, and the one that is cladistically closest to the stem 

 species C, is undoubtedly the polymorphic north African perennial A. pyrethrum. Nevertheless, 

 the hypothesis that it is a very specialized derivative species within the genus, and indeed in the 

 northern hemisphere Anthemideae as a whole, is confirmed by its possession of the autapo- 

 morphies 4, 5, 11, 13, 17, 18 and 37 (Table 2, Fig. 10 C). These include such character states as a 

 submerged basal caudex, heteromorphic leaves, leaf rosettes and creeping inflorescences, all 

 logically correlated adaptations to the montane habitats in which it occurs. Data on the 'Magde- 

 burg' officinal plant A. officinarum are also included, since it seems to possess synapomorphies 

 of both the perennial and annual species, superficially appearing to be an annual derivative 

 A. pyrethrum but possibly being an annual hybrid between this and the commonly cultivated 

 annual A. radiatus (Fig. 10). 



The naturally occurring annual species clearly form a monophyletic group derived from a 

 common ancestor with the perennials, as defined by the synapomorphies 1, 3 and 7. Within this 

 group, A. monanthos, a desert plant of eastern Algeria, Tunisia, Libya and Egypt, diverges at 

 the first dichotomy (Fig. 10 D) by possession of the autapomorphic character states 10, 12, 14 

 and 35. This interpretation makes it necessary to consider that the acauline habit and tough 

 involucral scales (as in A. pyrethrum) and the loss of ligules (as in A. homogamos) are independently 

 derived (character 25). Since A. monanthos seems to bear superficial resemblance to A. homogamos 

 and since these species appear to show vicariant distributions (Figs 15, 23) it is tempting to 

 consider that they share recent common ancestry. However, on the basis of such characters as 

 its hard, obovate overtopping receptacular scales and thick, rather unspecialized cypselas which 

 can always be readily distinguished from those of A. homogamos, a detailed re-interpretation of 

 character-state trends in A. monanthos would have to be considered. A. maroccanus, the next 

 closest annual to the stem species (Fig. 10 E), is, by comparison with the rest of the annuals, a 

 rather unspecialized Moroccan endemic retaining a number of plesiomorphous character states, 

 e.g. the red-pigmented undersides to the ligules and the narrow, triangular receptacular bracts of 

 A. pyrethrum. 



The remaining annual species form two distinct, but closely allied, groups of specialized weeds 

 hereby designated as the ''radiatus'' and 'clavatus' groups (Fig. 10 F, G, H). A. radiatus comprises 

 two distinctive subspecies: A. radiatus subsp. coronatus has white ligules which are occasionally 

 purple below and cypselas with an expanded lateral wing (Fig. 4); A. radiatus subsp. radiatus, 

 by comparison, has yellow ligules which are occasionally purple below (var. purpurascens) but 

 cypselas with a less widely expanded wing (Fig. 4). 



A. clavatus and its allies form the most advanced group in the genus in terms of increasing 

 apomorphy in characters 43, 46 and 48 (Tables 1, 2, Fig. 10 F). A. clavatus is cladistically closest 

 to the structurally reduced weed A. homogamos, and examination of many different herbarium 

 collections show that the latter species is distinguished mostly by its smaller habit, the absence of 

 ligules, and slightly broader and more auriculate cypsela wings. It is frequently confused with 

 apparently rayless forms of A. x valentinus, which are on the whole much more robust in capitulum 

 size and general habit. Because of the short, yellow ligules in this taxon, A. x valentinus is con- 

 sidered to be a hybrid between A. homogamos and A, radiatus (p. 128). 



A. linearilobus is a rare endemic, narrowly confined to the sand dunes of northern Algeria 

 (Fig. 25). It can be distinguished from A. clavatus by the unique features of the leaf and recep- 

 tacular bracts (characters 19, 20, 24 and 39). 



Finally, A. nigellifolius and A. latealatus, the eastern Mediterranean vicariant species pair 

 (Fig. 27), form the sister-group of A. clavatus and its immediate allies. Both species are structurally 

 simplified annuals showing considerable decrease in leaf area and inflorescence structure, with 

 the most apomorphous conditions apparent in the corolla and cypsela (characters 21, 22, 29, 

 33 and 36). 



