420 NOTES FROM THE BOTANIC GARDKNS, SYDNEY, 



These two instances of parthenogenesis in two, submerged 

 plants of so widely separated families seem to lead up to the 

 conception, that such a habit is likely to be very generally char- 

 acteristic of plants growing under similar conditions. At all 

 events, I have obtained considerable evidence in favour of this 

 view. Further investigation is in progress, and I hope to bring 

 further results before the Society, as opportunity occurs for 

 experimentation. 



Note on the Species of Elatine. 



The plant experimented on is our common Elatine. The 

 Southern species, in which Bentham includes the Australian 

 form, has been labelled E. minima Fisch. &. Meyer, (Linnasa, x., 

 73), E. grat.ioloides A. Cunn., (Ann. Nat. Hist., iii., 26, on New 

 Zealand forms), E. americana Arnott, by von Mueller, and E. 

 am,ericana Arnott, var. australiensis by Bentham. E. triandra 

 of Schrank was founded in 1791; and E americana Arnott, in 

 1814. 



Bentham says " The Australian species is considered b}' some 

 as endemic, by others as identical with an American one." And 

 aoain, " This plant, whether a distinct species or a variety of 



the N. American one, is very variable." He then notes 



various forms, those under water with elongated stems, and very 

 few with petals. There is no doubt that the external form 

 varies at once, as we have seen, even in the same individual, 

 when the conditions change. 



Britton and Brown, in their "Illustrated Flora of the Northern 

 United States," 1897, ii., p. 437, give descriptions and figures of 

 both E. americana and E. triandra. Of E. americana they state, 

 " Sepals, petals, stamens, styles 2 (rarely 3 in terrestrial forms)"; 

 and of E. triandra, "'Sepals commonly 2; petals, stamens, and 

 stigmas 3." In our specimens, the ti'imerism of all the parts is 

 conspicuous. Thus Bentham writes (I c), "The N. American 

 plant " [i.e., E. americana^ "differs chiefly in the flowers almost 

 constantly dimerous, which does not occur in any southern 

 specimens I have examined." 



Inasuiuch as the number of stamens present in the flowers is 



