DEVELOPMENT OF PLANTS 



471 



generate ragweeds the individual flowers of a head are very 

 uniform in structure. They are epigynous, parts usually in fives, 

 calyx wanting or more often appearing as tufts of hairs, plumose 

 or barbed bristles, and known as the pappus (Figs. 339, 341). 

 The corolla is tubular or partially split open, forming a strap- 

 shaped blade known as the ligulate corolla (Fig. 339, E). The 



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Fig. 338. Habit of the dandelion {Taraxacum), an example of the Cicho- 

 raceae: a, appearance of the inflorescence or head; b, appearance of the head 

 during the ripening of the seed ; in, involucre; c, appearance of the fruit. 



anthers are united about the style which is often hairy and pushes 

 out the microspores like a piston (Fig. 341, B-D). The style 

 is two-Iobed, the stigma usually appearing as a line on the inner 

 surface of the lobes and the single, one-ovuled carpel matures 

 as an akene. Scale-like bracts, the chaff, are often associated 

 with the flowers (Fig. 341, B). The nectar formed from the 

 glands at the base of the style is concealed at the bottom of the 

 corolla tube. 



