1917] FIELD CROPS. 735 



grass, tall oat grass, meadow fescue, English rye grass, Italian rye grass, tim- 

 othy, meadow foxtail, Poa fertilis, field brome grass {Bromus arvensis), red 

 clover, bird-foot clover, alfalfa, and yellow trefoil. In addition to the data 

 secured the results obtained by other Investigators are briefly reported. 



Pollination experiments conducted with orchard grass for several years 

 Indicated that the species, while generally cross-pollinated, produced seed to 

 some extent under self-fertilization. It was found that individual plants show 

 considerable variation with reference to self-fertility. Similar experiments, 

 but on a smaller scale, showed that tall oat grass under ordinary conditions 

 is predominantly cross-pollinated. Pollination experiments with meadow 

 fescue gave results very much the same as those secured with orchard grass. 

 The two species of rye grass proved chasmogamous. In a series of pollination 

 studies with timothy the plants behaved much like those of the foregoing 

 species, but the results also indicated that types comparatively high in fertility 

 when close-pollinated may be isolated. 



Meadow foxtail proved to be generally cross-pollinated and did not seem to 

 be lower in fertility when isolated than the species above mentioned. P. fertilis 

 under ordinary conditions was found to be cross-pollinated, but when i.solated 

 close-pollination resulted in complete fertilization, and under unfavorable 

 weather conditions during blossoming self-fertilization also took place. While 

 field brome grass gave complete fertilization with pollen from the same plant, 

 cross-pollination predominated when the weather conditions were favorable. 



The results with red clover indicated the practically complete self-sterility 

 of the plant. With reference to bird-foot clover it was concluded that cross- 

 pollination is necessaiT for seed production and that pollination is dependent 

 upon the action of insects. 



In the case of alfalfa natural self-pollination produced some seed but artifi- 

 cial self-fertilization was much more effective in this regard, while artificial 

 cross-pollination resulted in twice the number of seeds secured from artificially 

 self-pollinated plants. The author discusses the possible relation of climate 

 as a factor in this connection in addition to insects as pollinating agents. 



Yellow trefoil showed a certain degree of self-fertility. In all the experi- 

 ments conducted with this plant the blossoms of isolated individuals opened 

 automatically. 



Experiments with bird-foot clover and alfalfa in grass m.ixtures, E. I.ind- 

 HAED (Tidsskr. Planteavl, 23 {1916), No. 4, pp. 605-622, figs. 2).— The experi- 

 ments described were conducted at Tystofte from 1910 to 1913. The mixtures 

 used per tondeland (1.36 acres) in one series consisted of 8, 12, or 16 lbs. 

 of bird-foot clover and varying quantities of orchard grass, tall oat grass, tim- 

 othy, and Poa fertilis, the smaller quantities of grass seed being used with the 

 larger quantities of bird-foot clover seed and vice versa. Where bird-foot clover 

 was sown alone it was used at the rate of 20 lbs. per tondeland. The average 

 yields of hay per tondeland for the three different quantities of seed for each 

 mixture were as follows: Orchard grass 110, tall oat grass 140, timothy 120, 

 P. fertilis 121, and bird-foot clover alone 125 cwt. The quantity of bird-foot 

 clover in the hay of the different mixtures and the pure seeding was 36, 30, 43, 

 58, and 78 per cent, respectively. 



In a second series of experiments 12 or 20 lbs. of alfalfa seed per tondeland 

 was sown in a mixture of the different quantities of the grasses mentioned 

 above. For the pure seeding of alfalfa 30 lbs. of seed per tondeland was used. 

 The average yields of hay for the unit area for the two different quantities of 

 seed for each mixture were as follows : Orchard grass 156, tall oat gra.ss 178. 

 timothy 171, P. fertilis 161, and the pure seeding of alfalfa 1.59 cwt. The pro- 

 portion of alfalfa in the hay from these different seedings was 50, 47, 57, 74, 



