Two Kinds of Stamens with DIfferent Functions in 



the same Flower^). 



Mit 2 Textfiguren. 



To the Melastomacese and Commelynacese mentioned in Nature (vol. XXIV. 

 p. 307 -), vol. XXVL p. 386, and vol. XXVII. p. 30 ^)), may be added the genera 

 Mollia (Tiliaceas), Lagerstrcemia (Lythraceae), and HeterantJiera (Pontederiacese), 

 for having differently coloured anthers. In several species of Mollia, according 

 to Darwin ("Forms of Flowers", p. i6ö, footnote), the longer stamens of the five 

 outer cohorts have green poUen, whilst the shorter stamens of the five inner 

 cohorts have yellow pollen ; the stigma Stands close beneath the uppermost anthers, 

 In a Lagerstrcemia in my garden the six outer stamens have green pollen, and are 

 much longer than the numerous inner ones, which have bright yellow pollen ; the 

 Stigma Stands on a level with the outer anthers. I have repeatedly seen bees alighting 

 on, and gathering the pollen of, the inner anthers without noticing the outor ones. 

 In HeterantJiera reniformis there is one long stamen (belonging to the 

 outer whorl) having- pale bluish pollen, and two short stamens (of the inner whorl) 

 with bright yellow pollen. The stigma Stands generally on a level with the anther 

 of the long stamen. When the white flower opens, pistil and long stamen di- 



verge, the pistil bending (almost without exception) 

 to the right, and the stamen to the left ; at the 

 withering of the flower, they again approach each 

 other, so that the stigma may be fertilised by 

 the pollen of the long stamen. Visiting insects 

 are attracted yet more to the 3'ellow anthers of 

 the two short stamens by their being placed close 

 to a yellow spot, surrounded by a violet border 

 at the base of the upper petal. 



Fig. I. — Flower-spike of Heteranthera roüformis (natural size). 



Fig. 2. — Upper end of the flower-tube, seen froni behind. 

 a\ the one anther of the outer whorl, with pale bluish pollen ; 

 a, the two anthers of the inner whorl, with bright yellow pollen; 

 st, Stigma. 



Thus it may be safely assumed that in all these flowers, as well as in the 

 above-mentioned Melastomacese and Commelynacea?, fertilisation is almost exclu- 



1) Nature 1882/83. Vol. XXVII. p. 364, 365. 



2) Ges. Schriften S. 876. 



3) Ges. Schriften S. 960. 973. 



