REVISION OF ANACYCLUS 



93 



Fig. 3 Inflorescence types (see text for explanation). 



eastern Mediterranean annual A. nigellifolius (Fig. 2 J). Measurements are given in the descrip- 

 tions. 



Most leaves have a distinctly herbaceous texture, but those of A. linearilobus are quite fleshy. 

 A. linearilobus (Figs 2 J, 24) has the greatest degree of dissection in the sense that it has a small 

 leaf area relative to the dimensions of the leaves, the wide rhachis internodes and the long, 

 slender lobes. 



Some species, e.g. A. clavatus (syn. A. tomentosus) and A. pyrethrum var. depressus, have a 

 dense indumentum, whilst others, e.g. A. nigellifolius and A. linearilobus, are glabrous. This 

 character is extremely variable and has little taxonomic significance. The hairs are invariably 

 simple. 



Inflorescence 



A conspicuous feature in Anacyclus is the variation in arrangement of the capitula. These are 

 borne singly at the end of a single peduncle (as in A. nigellifolius) or, more commonly, a 

 branched peduncle (as in A. radiatus and A. clavatus), or they may be tightly grouped into a 

 central cymose cluster with lateral peduncles emerging from the axil of the leaf or bract (as in 

 A. monanthos). Examination of the different inflorescence types reveals that they represent several 

 modifications in a distinct evolutionary trend, which is outlined in Fig. 3. 



The most frequent condition is shown in Fig. 3 A ; this simply consists of a fairly dense cyme with 

 terminal capitula usually branching from the middle of a main stem. After the flowering of 

 the first capitulum, growth is maintained by lateral alternate branches which develop beneath the 

 capitulum and themselves eventually terminate in new capitula. The shaded capitulum in Fig. 3 A 

 symbolizes a mature, ripe head from an early stage of the flowering period, and the unshaded 

 heads the successive developments. This condition occurs in several species of Anacyclus, and 

 it is not uncommon in some of the more robust species (e.g. A. linearilobus) to see a main branch 

 lying prostrate with many successive flowering shoots emerging from its axis. 



Generally, the flowering period of the most widespread weed species, A. clavatus and A. radiatus, 

 spans several months, allowing several generations of capitula to develop on one plant. However, 



