SAXIFRAGEAE 



413 



981. P. palustris L. (Sprengel,'Entd.Geh./pp. 166-73; C.W.Ritter,inHoppe's 

 'Bot. Taschenbuch/ Regensburg, 1803, Nachschrift, p. 181; Delpino, ' Ult. Oss.,' 

 p. 168; Herm. Muller, 'Fertilisation,' pp. 247-8, ' Alpenblumen,' pp. 111-13 ; Kerner, 

 'Nat. Hist. PI./ Eng. Ed. 1, II, pp. 209, 213, 249, 251, 307 ; Verhoeff, 'Bl. u. Insekt. 

 d. Ins. Norderney'; Knuth, 'Bl. u. Insekt. a. d. nordfr. Ins./ pp. 34-5, 150, 'Bliiten- 

 biol. Notizen.') This species bears protandrous deceptive flowers. Their mechanism 

 was very fully described by Sprengel, but he remained in doubt as to whether 

 they were day or night flowers. Since Sprengel's time this most interesting flower 

 has been studied by Ritter, Hermann Muller, and others, and we are particularly 

 indebted to Muller for an explanation of the significance of its individual parts. 

 The five white petals are furrowed by colourless veins, and in front of them there 

 are five characteristic yellow-green organs, the staminodes, each of which possesses 

 a short broad stalk that expands into a disk bearing 7-13 or even as many as 

 25 stalked glands, serving to attract insects. Some nectar is secreted on either 

 side the insertion of the stalk. When the flower opens the anthers are still 



Fig. 134. Pamassia palustris, L. (after Herm. Miiller). A. Flower after removal of three sepals 

 and four petals, seen from above, immediately after opening. One stamen has lengthened, and its anther 

 lies upon the middle of the pistil, the stigma being still immature. This stamen is beginning to dehisce, 

 and to cover its upwardly directed outer surface with pollen. S. Flower after removal of calyx, corolla, 

 and staminodes. Four stamens have already shed their pollen and curved back ; the fifth, which is covered 

 above with pollen, lies upon the still immature pistil. C. The same flower in the second (female) stage. 

 The stamens have all dehisced ; the stigma, which is here represented as trilobed, but is usually four-lobed, 

 is mature. D. Staminode, more highly magnified, w, nectar ; p, petal ; s, sepal. 



unripe, their filaments are short, and they lie close to the conical pistil, the stigma 

 of which is also still immature. The stamens now ripen successively, their filaments 

 elongating to such an extent that the anthers lie exactly upon the top of the ovary, 

 their dehisced pollen-covered surfaces facing upwards. After about a day an anther 

 has shed its pollen and bends outwards, when another takes its place at the top 

 of the pistil, and so on. At the end of four days, when all the anthers are empty, 

 the apical stigma unfolds, occupying exactly the place taken up in the first (male) 

 stage by a ripe anther. 



The stalked glands of the staminodes attract insects by their glistening appearance, 

 which apparently suggests the presence of abundant nectar. The more intelligent 



