REVISION OF ANACYCLUS 



117 



5cm - A 



5mm- B-E 



2-5mm- F 



Fig. 14 Anacyclus monanthos subsp. monanthos'. A - habit, B - involucral bract, C - receptacular 



scale, D - floret, E - cypsela, F - anthers. 



monanthos, by contrast, is easily recognizable by a number of features and is usually known as 

 A. alexandrinus Willd. 



The habit, the type of inflorescence and the shape of the corolla lobes are the most important 

 varying characters. Others include the hardness of the mature fruits and receptacular scales, and 

 the size and number of capitula. 



Subsp. monanthos is particularly well defined in both morphology and distribution. In the 

 eastern part of its distribution it shows the most marked extremes in its acauline prostrate habit, 

 the development of syncephalous and clustered capitula along with reduction and fasciation in 

 the peduncles, the presence of prominent rosette leaves with very broad, cuneate rhachis bases, 

 and the heaviest thickening in the mature fruits and receptacular scales. All these features appear 

 to be adaptations to the extremely dry, hot conditions experienced in the desert. By contrast, 

 subsp. cyrtolepidioides is less prostrate and even decumbent in Algerian and Tunisian collections, 

 it does not have central basal clusters of capitula or syncephala, it rarely has fasciated peduncles 

 and it sometimes has a short central stem. There is a marked absence of rosette leaves, the cypsela 

 wings are thinner, and the cypselas are only slightly overtopped by the thickened cuspidate apices 

 of the receptacular scales. 



Both subspecies seem to occur in small discrete populations; but they come into contact in 

 southern Tunisia and Tripolitania, where the differences between them are not quite as clear-cut 

 as the above descriptions may suggest, several intermediate specimens having been found. 

 Nevertheless, the vicariant, stepped-clinal variation between the extremes indicates a divergent 

 allopatric speciation pattern. 



