ERICACEAE 



33 



the ovary, running parallel to the style, and each of them bears two inwardly directed 

 anther-lobes, which open by pores below, and are produced into tail-like appendages 

 extending to the corolla. 



Only the most skilful insects, humble-bees and bees, are able to get at the nectar 

 quickly and easily, by hanging on to the flower from below and probing for it through 

 the small opening of the corolla. In doing this the proboscis is almost certain to 

 touch, and if previously dusted with pollen to pollinate the stigma, which lies a little 

 distance within the opening of the corolla and is covered with a thick sticky fluid. It 

 next strikes against one or more of the 20 tail-like anther-appendages, causing some 

 of the smooth pollen-grains 

 (loosely aggregated into te- 11 A 



trads) to fall upon it. Cross- 

 ing is thus ensured by insect- 

 visits. 



Kerner states that the 

 flowers are very feebly pro- 

 togynous. Towards the end 

 of anthesis, should insect- 

 visits fail, pollen falls upon 

 the stigma, which is at a 

 lower level than the anthers, 

 so that automatic self-pollina- 

 tion is possible as a last 

 resort. 



In plants observed by 

 Lindman on the Dovrefjeld 

 the flowers were strongly 

 fragrant. The appendages 

 of the anthers are much 

 shorter in this locality than 

 in the Alps, but the edge of 

 the stigma is produced into 

 a rim, so that automatic 

 self-pollination can more 

 easily be effected. Warming 

 states ('Arkt. Vaxt. Biol.,' 

 pp. 18-21) that autogamy is 

 also easily possible in Green- 

 land, and is effective. In that country the flowers are homogamous, while the 

 anthers dehisce and the stigma becomes receptive in the bud. 



Visitors. The following were recorded by the observers, and for the localities 

 stated. 



Herm. Miiller (Alps), 3 humble-bees skg. legitimately and one perforating the 

 flowers, a Lepidopterid (as an unbidden guest), and Thrips (do.). Lindman, 

 2 humble-bees. MacLeod (Pyrenees), a humble-bee (Bot. Jaarb. Dodonaea, Ghent, 

 iii, 1 89 1, p. 374). Hoppner (Bremen), the humble-bee Bombus agrorum F. 5, skg. 



Fig. 219. Arctostaphylos Uva-tirsi, Spreng. (after Herm. Miiller). 

 A. Flower seen from the side ( x 3). B. Do. from below. C. Sketch 

 of interior of bud shortly before opening ( x 7). D. Stamen ( x 15). 

 E. Flower cut through transversely under the anthers, seen from 

 below (x 7). F. Calyx, ovary, and nectary, seen from below (x 7). 

 G. Ovary and nectary turned up, and seen from the side (X 7). H. A 

 flower perforated by Bombus mastrucatus. a, anthers ; gr, style ; 

 w, nectary; ov^ ovary; /, petals; s, sepals; st, stigma. 



