1946 A TEXTBOOK OF THEORETICAL BOTANY 



fullonuni, the Fuller's Teasel, the hooked bracteoles (Fig. 1876) of which 

 are used to raise the nap on woollen cloth after weaving. 



The family is entirely absent from America, Australia and Polynesia. 



Fig. 1876. — Dipsocus ftillonum. Teazle. 

 Inflorescence with long involucral bracts 

 and numerous hooked bracteoles which 

 subtend the individual flowers. 



Compositae (Asteraceae) 



This is the largest and most widely distributed of all families of the 

 Angiosperms and probably represents the highest stage in the evolution of 

 the Dicotyledons. It has been estimated that there are some 13,000 species, 

 which is approximately 10 per cent, of the Flowering Plants. Although the 

 family is so large its members show a marked similarity in floral structure, 

 so marked in fact that they cannot be confused with those of any other 

 family, although they have a superficial resemblance to members of the 

 Dipsacaceae. 



The variety of habitats which the species occupy is extremely diverse, 

 while even within the confines of a single genus they display a corresponding 

 variety of forms. It is interesting to note that the shrubby species often 

 form an important feature of the Composite flora of oceanic islands. 



Of this vast assemblage of species only comparatively few are represented 

 in the British Flora, but, even so, the number of common species is con- 

 siderable and it is impossible here to do more than mention a few^ of the 

 most obvious. Among the commonest weeds are the Dandelion ( Taraxacum 

 officinale) (Fig. 1877), Daisy [Bellis peremiis), Hawkweeds [Hieracium), 

 Sow Thistle (Sonclius), Thistle {Car dims). Yarrow {Achillea)^ Scentless May- 

 weed {Matricaria inodora), Groundsel {Senecio vulgaris), Ragwort {Senecio 



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