THE GERMINATION OF SOME TREES AND SHRUBS 

 AND THEIR. JUVENILE F0R:\IS. 



L. H. PAMMEL AND C. M. KING. 

 (Contribution No. 2 on Germination of the Woody Plants.) 



In the proceeding's of the Iowa Academy of Science, 1917, we • 

 published a paper on the germination and the juvenile forais 

 of some oaks, mostly species native to Iowa. In this paper some 

 of the literature on the subject was oiven. C. S. Sarg.ent^ has 

 touched on the genmination of many of the species of North 

 Ani'erica, in some cases in detail. Germination of exotic species 

 is described by Tubeuf.- It seemed well, therefore, to continue 

 observations on the germination of Iowa species, and a few not 

 native to the state are included. Little specific seems to be 

 known about the vitality of tree and shrub seeds. The state- 

 ments made are usually quite general. The species here studied 

 were treated as to seed bed conditions in two ways. One lot of 

 seeds was placed in good greenhouse soil in the fall (1917) and 

 stratified in a cold frame, from whicdi they were removed to the 

 greenhouse in March, 1918. The second lot was planted in an 

 open place covered with two inches of soil and leaves. Air 

 temperature records were ke})t throughout the season, soil tem- 

 perature records were kept in the fall until the ground was 

 frozen, and again during the opening of the growing period of 

 1918. 



Show^ calls attention to the need of testing every lot of seed, 

 these tests to be co-ordinated with actual germination in the 

 nursery. His paper describes a series of tests of seeds of yellow 

 pine, Jeffrey pine and incense cedar. He considers five factors 

 influencing germination; 1. temperature of soil; 2. character of 

 soil; 8. amount of light; 4. amount of water, and 5. depth of 

 cover. The last three factors can be quite well standardized ; 

 character of soil is predetermined ; temperature is consequently 

 the variable. The germination of the three conifers is more 

 rapid and complete in fertilized soils and slowest in clay. He 

 finds that mean temperature does not apply strictly to germina- 

 tion. An examination of greenhouse germination shows that 

 after two days with the same mean the germination increases 



^S'llva of North America, various volumes. 

 ^Tubeuf, K. Samen, Friiehte u. Keimlinge. Berlin, 1891. 

 ^Show, S. B., The Relation of Germination in the Greenhouse and Nursery ; 

 Jour, of Forestry, J6, pp. 319-328. 



