90 



GRASSES OF IOWA. 



substances, nor do they form nitrogen gas. T. H. Schloesing, 

 Jr ,* who experimented with lupines, concludes that the seeds 

 of plants do not lose any of their nitrogenous substance in the 

 form of gas during germination. Soon after germination is 

 under way the primary root produces lateral rootlets; these as 

 well as the main root form root hairs that serve to bring nour- 

 ishing material from the soil as well as to anchor the plant. 

 The following table by Nobbe is interesting as showing the 

 germination of grasses compared with other plants. 



Agrostis stolonifera 



Pinua strobus . 



Allium cepa 



Alopecurus pratensia 



Arrhenatherum avenaceum 



Avena sativa 



Phleum pratense 



Zea mays 



Brassica oleracea 



Daucus carota 



Linum usitatissimum 



Medicago sativa 



Trifolium pratense 



Lactuca sativa 



Meadow grasses 



Cereals 



Crucif ers 



Cucurbits 



28 

 13 

 63 

 9 

 55 

 98 

 86 

 87 

 47 

 58 

 89 

 86 

 87 

 37 



27.4 

 81.5 

 87 

 74 



Temjjerature and germination. — It is a well known fact that 

 temperature is an important factor in the germination of seeds. 

 Nobbe fhas given us an instructive table, from which the fol- 

 lowing is taken : 



*Oomt. rend. 120: 1278. Abst. Cent. Agrikulturch. 25: 737. 

 tHandbuch der Samenkunde. 226. Landw. Versuchs. Stat. 117: 74. 1874. 



