Profieeding'S of the Relf.ast Natural History and Philosophical Sooiety, 1920-1921. 



lJi.th and 3Sth January, 11th and 25th February, 1921. 

 The President, Professor Gregg Wilson, in the Chair, 



A Course of four Lectures on 



SOME CHAPTERS IN MODERN BOTANY. 



By James Small, D.Sc, Ph.C, F.L.S., 



P)vfesfior of Botany, Queen's Univer^sity, Belfast. 



In Biological Lecture Theatre, Queen's University. 



I.— THE WANDERINGS OF THE GROUNDSEL. 



The Groundsel, Senecio vulgaris, is commonly regarded as 

 only one species ; that single siiecies, however, includes a miscel- 

 laneous group of about one hundred microspecies, and for the 

 purpose of this lecture the name " Groundsel " is extended 

 beyond that familiar canary food to all its relatives which are 

 included in the genus Senecio. Taking " Groundsel " as 

 synonymous with Senecio, we deal, not with one species, but 

 with al)out 2,500 species, ranging over all the habitable surface 

 of the earth, and with a type which may be regarded as older 

 than the Alps and Himalayas. 



. At a period which is variously estimated as from 4 millions 

 to 40 millions of years ago none of the existing high mountain 

 ranges were in existence. As the earth began to emerge from 

 what is known as the Cretaceous Period, the western parts of 

 South America were flat, and the region of the Amazons was 

 covered, as it is to-day, by a very mixed, dense forest. The few 

 herbaceous and semi-shrubby plants which gi'ew in such forests 

 were epiphytes or climbers, and amongst the semi-shrubby 

 climbers wei-e the ancestors of the groundsel. This ancestral 

 type still lingers in the same region, as the genera Siphoca^npyhis 



