ERICACEAE 51 



also some small flowei-beelles (Meligethes sp.) and 2 Muscids (Anthomyia sp., and 

 Opomyza germinalionis /.). Scott-Elliot (Dumfriesshire), a humble-bee, a jMuscid, 

 a micro-Lepidopterid, and a beetle (' Flora of Dumfriesshire,' p. 113). 



1782. P. rotundifolia L. (Warming, op. cit., p. 124 ; Herm. Miiller, op. cit., 

 p. 376; Lindman, ' Bidrag till Kanned. om Skandin. Fjellvaxt. Blomn. o. Befrukt.'; 

 Knuth, ' Bl. u. Insekt. a. d. nordfr. Ins.' pp. 102-3; Warnstorf, Schr. natw. Ver., 

 Wernigerode, xi, 1896, p. 7.) — The flowers of this species examined by me at Kiel 

 \vere white in colour with an open bell-shaped corolla, devoid of nectar, feebl)' 

 odorous, and homogamous (strongly protandrous according to Warnstorf. Their 

 mechanism is at first adapted to crossing, and subsequently, as a rule, to automatic 

 self-pollination. This change is brought about by a gradual alteration in the direction 

 of growth of the style, which is at first directed almost vertically downwards, sometimes 

 with a slight upward curve, so that the line of fall of the pollen is about 8 mm. in front 

 of the stigma. The end of the style subsequently bends upwards, bringing the stigma 

 vertically below the opening of the anthers, so that autogamy follows automatically by 

 the fall of pollen (Fig. 231). Lindman says that in plants growing on the Dovrefjeld 

 automatic self-pollination finally becomes 

 possible, for the anther-pores, at first 

 basal, are brought into a suitable position. 



In this species again the stigma 

 secretes a large amount of sticky fluid, 

 from which five conical elevations pro- 

 ject, and the pores of the 3'ellow 

 anthers are surrounded by an orange- „ ,.-,.,- 



•^ ^ Fig. 231. Pyyola roUuidtfolia^ z.. (trom natuiej. 



yellow band. Warnstorf states that the d) Stami-ns and pistil in tiie first condition of the 



,, ^ . 1 ■ J- , flower; the stigma is not in the line of fall of tlie pollen. 



pollen-tetrads are 37 //. m diameter. ,_,, ^o., in th. second stage of anthesis: the stigma 



Visitors -These are verv few in ''^^ vertically below the tips of tiie anthers, from which 



the pollen is distributed. 



number. On the Meimersdorfer Moor 



near Kiel, where this plant grows in association with Parnassia palustris, 1 observed 

 large numbers of insects visiting the latter (11 and 14. 9. '92), but, though 1 watched 

 for a long time, was unable to see a single insect visiting the Pyrola, though it was 

 quite as conspicuous. On flowers taken into my study I noticed several house-flies, 

 touching the stigmas, anthers, and petals with their proboscis, but after a few vain 

 attempts to find nectar they quickly went away again. Alfken observed no visitors 

 in Norderney. 



Warming has examined herbarium specimens of the var. armaria Koch in 

 which the stigma and anthers are closer together than in the type-form, so that 

 automatic self-pollination would appear to be effected more easily. 



Visitors. — Verhoeff observed none in Norderney. 



1783. P. grandiflora Rad. (Kolderup Rosenvinge, Mcddel. om Gronland, xv, 

 1896, p. 68; Abromeit, ' Bot. Ergeb. von Dr3'galski's Gronlandsexped.,' p. 48.)— 

 Rosenvinge states that there are transitions between this arctic species and P. rotundi- 

 folia. The Greenland specimens described by Abromeit possess an external annular 

 swelling at the base of the calyx which is absent in the latter, while the calyx-teeth 

 are shorter (usually less than half that of the petals), broader, and often dentate 

 at their ends. 



