PHYSIOLOGICAL STUDY OF MAPLE SEEDS 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 2 60 



H. A. Jones 



(with two figures) 



Introduction 



The appearance of two taxonomic species within the same 

 genus is not always a criterion of similar physiological or ecological 

 behavior. The seeds of two closely related species, as those of 

 the sugar and river maples (Acer saccharum Marsh, and A. sac- 

 charinum L.), show a striking contrast in season of maturity, 

 reaction to external conditions, chemical composition, and in their 

 physiological behavior in general. The sugar maple matures its 

 seeds in the fall, and these must pass through a well defined period 

 of after-ripening before germination can take place. The storage 

 substances are mainly protein and fat, with a small amount of 

 carbohydrate present. On the other hand, the river maple ripens 

 its seeds in the spring. The seeds germinate almost immediately 

 upon a moist substratum, but if allowed to desiccate for some time 

 under ordinary atmospheric conditions they soon lose their power 

 of germination. A very small percentage of fat and protein is 

 present, starch being the chief storage product. 



It is a matter of common observation that many mature seeds 

 and spores soon lose their power to germinate when subjected for 

 varying periods to atmospheric desiccation. In a great many 

 tropical seeds death follows atmospheric drying. In our own 

 region the seeds of the willow and cottonwood are usually cited 

 as the classic examples of death due to desiccation shortly after 

 seed fall. The cottonwood gives low percentage of germination 

 and low seedling vigor after two weeks of desiccation in laboratory 

 air, while after three weeks seeds fail to germinate when placed in 

 the most favorable germinative conditions. Cottonwood seeds, 

 however, are in a high state of metabolic activity when first shed. 



127] 



[Botanical Gazette, vol. 69 



