CHAP. VII. GYNO-DKECIOUS PLANTS. 3Q3 



cess of females I do not know. In the females the 

 pistil is rather longer than that of the hermaphrodite, 

 and the stamens are mere rudiments, with minute col- 

 ourless anthers destitute of pollen. The windows of the 

 green-house were left open, and the flowers were inces- 

 santly visited by humble and hive bees. Although the 

 ten females did not produce a single grain of pollen, 

 yet they were all thoroughly well fertilised by the one 

 hermaphrodite plant, and this is an interesting fact. 

 It should be added that no other plant of this species 

 grew in my garden. The seeds were collected from the 

 finest female plant, and they weighed 78 grains; whilst 

 those from the hermaphrodite, which was a rather larger 

 plant than the female, weighed only 33.2 grains; that 

 is, in the ratio of 100 to 43. The female form, there- 

 fore, is very much more fertile than the hermaphrodite, 

 as in the two last cases; but the hermaphrodite Was 

 necessarily self-fertilised, and this probably diminished 

 its fertility. 



We may now consider the probable means by which 

 so many of the Labiatse have been separated into two 

 forms, and the advantages thus gained. H. Miiller * 

 supposes that originally some individuals varied so as 

 to produce more conspicuous flowers; and that insects 

 habitually visited these first, and then dusted with 

 their pollen visited and fertilised the less conspicuous 

 flowers. The production of pollen by the latter plants 

 would thus be rendered superfluous, and it would be 

 advantageous to the species that their stamens should 

 abort, so as to save useless expenditure. They would 

 thus be converted into females. But another view may 

 be suggested: as the production of a large supply of 

 seeds evidently is of high importance to many plants, 

 and as we have seen in the three foregoing cases 



* ' Die Befruchtung der Blumen,' pp. 319, 326. 



