Seeds and Their Germination. 



29 



weeks before a second one appears, which is followed by 

 others at shorter intervals. Evidently the loss of one or 

 two of the first leaves would not kill the young peony. 

 It is, therefore, able to take advantage of warm weather 

 and moist soil in early spring without the risk of serious 

 injury by late frosts. The leaves prepare starch, which is 

 stored in the roots to help the stem make a rapid growth 

 after all danger from frost is over. 



One of our native morning-glories seems to germinate 

 after the fashion of its relatives, but what 

 appears to be the hypocotyl bearing the 

 cotyledons is really the united stems (peti- 

 oles) of the cotyledons. The plumule 

 between their bases remains inactive for a 

 time and then comes out through a slit in 

 the petiole tube as shown in the figure. 

 This peculiar growth of the petioles and 

 the epicotyl reminds one of Big-root; but 

 in that plant the growing petioles force 

 the caulicle and plumule deeper into the 

 ground, while in the morning-glory the 

 caulicle puts out side-roots which cause 

 the petioles to push the cotyledons up into 

 the air, while the plumule remains nearly 

 where the seed was planted. The scarlet 

 larkspur germinates in a similar manner. 



For the next exercise get an entire her- 

 baceous plant of several months' growth. 



Fig. 23. A native 

 morning-glory in ger- 

 mination, p. United 

 petioles, c. Caulicle. 

 The plumule not yet 

 above ground. [This 

 is Bentham's Convol- 

 vulus Subacaults.} 



Some weed less 



