350 Mr Willis, On Gynodicecism in the Labiatae. [May 30, 



gynodioecism. If Lud wig's* view be correct, that the primary 

 cause is the protandry of the flower, rendering the stamens of the 

 earlier flowers useless, we might expect to find these variations 

 more frequent at the commencement of the flowering season. 

 This was tested as follows: Ten cuttings were taken from the 

 same parent stock, and grown under similar conditions : every 

 flower was carefully examined. The abnormalities were most 

 erratic in their occurrence, and I was unable to discover any con- 

 ditions governing this point. No two of the plants gave results 

 corresponding in any way, nor did the average follow any ap- 

 parent rule. Some bore about the same percentage of abnormal 

 flowers throughout the season, others bore them many at one 

 time, few at another: e.g. No. 1 bore 126 females altogether; 73 of 

 these appeared in three days, and of these 29 were upon one small 

 lateral branch of the inflorescence. It may however be noted that 

 the percentage of abnormalities was much lower than in 1890, 

 being only 2 per cent. ; a result possibly due to the plants 

 being cultivated, and having no competition with one another for 

 space. 



One plant was protected from insects by a muslin net through- 

 out the flowering season, and did not, though it bore hundreds of 

 flowers, set a single seed capable of germination. It should be 

 noted, that owing to the smallness of the meshes, the plant could 

 not be shaken by the wind. 



Observations were also made (1891) upon Nepeta Glechoma 

 (wild). Two lots of plants were examined, one (A) growing on a 

 dry sunny bank, the other (B) in deep shade in a wood. The 

 latter commenced to flower 18 days later than the former and 

 were much taller and less hairy. 



The numbers of plants in flower and the numbers of open 

 flowers were counted weekly during the flowering season, and it 

 was found, as Ludwig has observed in the case of thyme, that the 

 proportion of female to hermaphrodite plants in flower was greater 

 at the beginning than at the end of the flowering season. For 

 example in lot A, on the first day 6 female plants and one 

 hermaphrodite flowered ; the percentage of females being 857. A 

 week later it was 33'6 per cent., and near the end of the season 

 was 236 per cent. In lot B, the percentages each week were 50 - , 

 16', 35-8, 28-5, 23-4, 19*2, 28-3. 



It was noticed that the female plants generally bore more open 

 flowers at one time than the hermaphrodites. In lot A the 

 number of flowers on each female plant was (on an average for the 

 whole season) 2*40, and on each hermaphrodite 216. In lot B 

 the numbers were 3'15 and 2"16. The greater size of the her- 



* " Ueber die Bliithenformen von Plantago lanceolata L. und die Erscheinung 

 der Gynodiocie." Zeitschr. f. d. Ges. Naturw. Lit. 1879. p. 441. 



