Alternating Annual and Biennial Habit. 299 



beet, sown at the same time, was biennial. The same 

 is true with other species. Seeds of the wild Daueiis 

 Carota saved from annual plants gave me a large pro- 

 portion of annuals; but seeds from plants which had 

 come through the winter gave a predominant proportion 

 of biennials. On the other hand selection does not seem 

 to lead to the production of annual races which would 

 be free from occasional atavism. It is my custom now 

 to cultivate my Oenothera Laniarckiana and its derivative 

 species mostly as annuals. Many of these cultures have 

 been continued for six or more generations by means of 

 the seeds of annual specimens only. Nevertheless every 

 year there occur occasional and sometimes several bien- 

 nial plants amongst them. 



Aster Tripoliiini^ is usually given as an annual in 

 the floras, but with us it is represented by specimens 

 which pass through the winter as well as by plants which 

 flower in the first summer. In experimental sowings in 

 the garden I obtained roughly equal numbers of the two 

 types; but if I sowed the seed in March or April in the 

 greenhouse the plants developed stems in the first year 

 almost without exception. They were, as a rule, covered 

 with glass every night until June, and thus protected 

 from night frosts, and they were well treated also in 

 other respects, especially by transplanting them soon 

 after germination into rich well-manured garden soil. 

 For according to my experience one of the best means 

 of inducing biennial plants to behave as annuals is to give 

 them plenty of manure, provided of course that the 



^KocH, Synopsis Florae Germanicac et Hclvcticac, p. 361. Gke- 

 NiER ET GoDRON, Flove dc Fvancc, Vol. II, p. 102; Kaksch. I'adc- 

 mccum hotanicum etc. 



