210 STUDIES IN THE POLLINATION ON INDIAN CROPS 



stigmas and often at a slightly bigLer level. A few minutes later when the 

 flower is fully open and the rupture of the anthers is complete, they close in on 

 the stigmas and self-pollination takes place. Thus self-pcllinatim takes place 

 automatically by the help of the expansion of the corolla. At a little later 

 stage, the burst anthers often fall together forming a cap over the stigmas— a 

 movement which renders self-pollination a practical certainty. In many 

 flowers it was observed that after the anthers begin to burst, twisting of the 

 styles occurred which helped to move the burst anthers through 90° thus 

 bringing their pollen-covered surfaces close to the stigmas. This twisting also 

 brought the stigmas to a slightly lower level and so assisted the burst anthers 

 to fall together and form a cap over the stigmas. In many cases the styles 

 untwist after the anther cap is formed, a circumstance which still further 

 favours self-pollination. 



Cross-fertilization. Small bees visit the flowers for honey about 10 a.m. 

 While collecting honey from the five nectaries, they occasionally come in contact 

 with the burst anthers and with the stigmas so that cross- j)ollina tic n is possible. 

 That crossing may occasionally take place in India has been proved by a study 

 of the cultures obtained from the seed of single plants. In 1916, the seed ot 340 

 bagged plants was sown of which 334 bred true. Splitting tcck place in six 

 cultures only — one gave rise to plants with different shades cf blue flowers 

 while five cultures produced plants differing in habit of growth. In 1917, the 

 seed of 233 bagged plants was sown. All bred true except one which split as 

 regards habit and flower colour. In 1918, the seed of 232 bagged plants was 

 sown all of which bred true. All these observations indicate that in the field 

 crossing is more frequent than would be suspected from a study of the flower. 

 That this is so was confirmed by the results of sowing separately the unbagged 

 seqd of all the cultures raised in 1917. In these 233 cultures, stray plants were 

 found in five cases as follows : — 



No. 1 (white flowers). Two blue-flowered plants appeared which next year 

 gave 84 blue and 32 white-flowered plants in one case and 129 blue and 34 white 

 in the other, or a total of 213 blues to 66 whites. 



No. 23 (white flowers). One blue-flowered plant occurred which gave 

 next year 52 blue-flowered and 12 white-flowered plants. 



No. 165 (white flowers). One blue- flowered plant was found which next 

 year gave 84 blue-flowered to 19 white- flowered offspring. 



No. 170 (pale blue flowers). One dark blue-flowered plant appeared 

 which split as regards shape of petals, colour of pollen (white or yellow), and 

 colour of petals — white and shades of blue from very pale to very dark blue. 

 The ratio of total blues to whites was 264 ; 7. 



