LUTHER BURBANK 



peratures of the globe in successive ages — a time 

 of tropical warmth being succeeded by an ice age 

 — resulted in subjecting the plant at different 

 periods to wide extremes of temperature. 



A vast number of species were in this way 

 wiped out of existence. 



But those that survived developed powers of 

 resistance which were in many cases subsequently 

 lost when the plants migrated to the tropics, or 

 when tropical conditions prevailed; but which 

 remained as latent influences in the germ-plasm, 

 susceptible of being brought out again under 

 proper conditions of hybridization. 



Thus, in order fully to understand the anom- 

 alous habit of the new Winter Rhubarbs, it is 

 necessary to recall that their immediate ancestors 

 came from another hemisphere, and that traits of 

 their latent heritage from remote ancestors both 

 of tropical and sub-Arctic habit were brought to 

 the surface under influence of the new conditions 

 of environment to which they were transplanted; 

 and the further influence of new crosses and of 

 constant selection through many generations. 



All in all, the new Giant Crimson Winter Rhu- 

 barb is a plant that presents points of interest for 

 the student of heredity and for the practical plant 

 developer, no less than for the practical horticul- 

 turist. And for the latter — whose interests, of 



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