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blossoming, and the slender beak of each flower elongates and raises 

 the pappus of capillary bristles while the fruit is forming. The 

 whole involucre, which is a double row of bracts, is then reflexed, 

 exposing the nearly mature naked achenes or fruits with the pappus 

 in an open globular head ready to be widely distributed by the wind. 



PROPAGATION. 



The dandelion is propagated by seeds. However, when once it 

 has gained possession of the soil it will hold on to it persistently, per- 

 petuating itself by heavy seeding, and also by its large, thick, fleshy, 

 deeply-penetrating roots which resist occasional cutting by sending 

 up new sprouts as discussed later in this bulletin. 



PARTHENOGENESIS AND SEED PRODUCTION. 



Seed production is an important phase in the life history of the 

 dandelion since it is the one important means of distribution of the 

 plant. At the outset of the work with dandelion eradication a 

 study of the problem of seed production was started. The belief 

 seems to be quite generally prevalent that the transfer of pollen from 

 the stamens to the stigma of the pistil is necessary before seeds can be 

 produced on the dandelion. However, in the common dandelion 

 (Taraxacum officinale), at least, pollination is not only unnecessary, 

 but may be, perhaps, altogether unimportant as a factor in seed 

 production. Evidently, parthenogenesis, or apagamous development 

 of the embryo, occurs in this species. As early as 1903, Raunkiaer 

 performed some experiments on several forms of Taraxacum by 

 employing a method of castration in which both anthers and 

 stigmas of unopened buds were sliced off with a sharp knife. From 

 the results of his work he announced that dandelions in Denmark 

 are parthenogenetic; that is, they produce fruit freely without fer- 

 tilization. Juel (1904), and later, Murbeck (1904), followed up the 

 work of Raunkiaer with careful cytological investigations of the 

 tetrad formation in the ovule, and found that parthenogenesis does 

 occur in the genus Taraxacum. Murbeck studied Taraxacum vulgare 

 which produces abundant, but imperfect pollen, and T. speciosum 

 which produces no pollen at all. However, Dahlstedt (1904) stated 

 that, in Belgium, there are two or three species of Taraxacum in 

 which pollination seems necessary. Schkorbatow (1910), as a result 

 of his studies of parthenogenesis in the genus Taraxacum, stated that 



