446 



EXPJEEIM£yTS WITH PLANTS 



In Fig. 249 is shown a leaf of Lamarck's Evening 

 Primrose and also one of a new species which sprang 

 from it, namely, the Broad Evening Primrose (CEno- 



thera lata). The latter leaf 

 is not only somewhat shorter 

 and broader, but is blunt in- 

 stead of pointed at the tip. 

 This was the first species to 

 originate in Professor deVries' 

 cultures. The seed of the 

 Lamarck's Evening Primrose 

 which he had gathered in an 

 abandoned field and sown in 

 his garden produced, the first 

 season, among a large num- 

 ber of ordinary plants, three 

 which were distinctly differ- 

 ent from the rest though 

 closely similar to each other. 

 They had broader, less pointed leaves, swollen buds 

 and small fruits: the stems were noticeably small, 

 weak and brittle: at the tips of the branches the 

 young leaves and buds were collected in crowded 

 rosettes so that the plants \\eve at first called "round- 

 heads." Most curious of all, these plants were entirely 

 unable to produce good pollen. Such was the origin 

 of the Broad Evening Primrose; and each subsequent 

 year, as the seed of the Lamarck's Evening Primrose 



249. Leaf of Lamarck's Evening 

 Primrose on tlie riglit, and of 

 Broad Evening Primrose on the 

 left. 



