ii8 MORPHOLOGY 



Wainio', who has studied every stage of development in the Cladoniae, 

 has described the scyphus as originating in several different ways : 



a. From abortive Apothecia. In certain species the apothecium 

 appears at a very early stage in the development of the podetium of which 

 it occupies the apical region. Owing to the subsequent formation of the 

 tubular cavity in the centre of the stalk, the base of the apothecium may 

 eventually lie directly over the hollow space and, therefore, out of touch 

 with the growing assimilating tissues; or even before the appearance of the 

 tube, the wide separation between the primordium of the apothecium and 

 the gonidia, entailing deficient nutrition, may have produced a similar effect. 

 In either case central degeneration of the apothecium sets in, and the 

 hypothecial filaments, having begun to grow radially, continue to travel in 

 the same direction both outwards and upwards so that gradually a cup- 

 shaped structure is evolved — the amphithecium of the fruit without the 

 thecium. 



The whole or only a part of the apothecium may be abortive, and the 

 scyphus may therefore be entirely sterile or the fruits may survive at the 

 edges. The apothecia may even be entirely abortive after a fertile com- 

 mencement, but in that case also the primordial hyphae retain the primitive 

 impulse not only to radial direction, but also to the more copious branching, 

 and a scyphus is formed as in the previous case. It must also be borne in 

 mind that the tendency in many Cladonia species to scyphiform has become 

 hereditary. 



Baur^, in his study of CI. pyxidata, has taken the view that the origin of 

 the scyphus was due to a stronger apical growth of the hyphae at the 

 circumference than over the central tubular portion of the podetium, and 

 that considerable intercalary growth added to the expanding sides of the cup. 



Scyphi originating from an abortive apothecium are characteristic of 

 species in which the base is closed (Wainio's Section Clausae), the tissue in 

 that case being continuous over the inside of the cup as in CI. pyxidata, 

 CI. coccifera and many others. 



b. From polytomous Branching. Another, method of scyphus forma- 

 tion occurs in CI. amaurocrea and a few other species in which the branching 

 is polytomous (several members rising from about the same level). Con- 

 crescence of the tissues at the base of these branches produces a scyphus ; 

 it is normally closed by a diaphragm that has spread out from the different 

 bases, but frequently there is a perforation due to stretching. These species 

 belong to the Section Perviae. 



c. From arrested Growth. In most cases however where the 

 scyphus is open as in Cl.furcata, CI. squamosa, etc., development of the cup 



^ Wainio 1897. 2 Baur 1904. 



