208 



ANGIOSPERMAE—DICOTYLEDONES 



P. sylvatica, but they are almost horizontal, and the corolla-tube is only lo-i i mm. 

 long. Humble-bees with a proboscis 8-9 mm. in length can, therefore, reach the 

 nectar by inserting their heads into the entrance. In correspondence with this, the 

 open slit of the flower above its toothed lower part is scarcely more than \ mm. wide, 

 so that the proboscis or head of a humble-bee will enlarge it noticeably or even 

 considerably. The edges of the upper lip are thickened above the place where the 

 reflexed margins pass into the outer ridges, and when a humble-bee forces its way 

 into the slit this must be opened right up to the tip, some of the pollen being bound 

 to fall out. The horizontal position of the flower secures that a humble-bee, though 

 its proboscis is inserted at a lower level, shall immediately touch the stigma, effecting 

 pollination if another flower has previously been visited. Pollen is discharged so 

 close to the insect's head that arrangements to prevent it from being wasted at the 



Fig. ,^05. Pedicuiaris palnstris, L. (after Herm. Miiller). A. Flower seen 

 tVom the left side (x 3^). B. Do., after removal of part of the calyx, the lower Up, 

 and most of the left half of the upper Up ( x 3J). C. Flower seen from the front after 

 removal of part of the calyx and most of the lower lip ( X 5). D. Transverse section 

 of the upper lip on the line cd '\n C {y. "]). E. Ovary and nectary from the side. 

 F. Do., from the front (X 7). ^.junction of serrated and smooth part of slit in upper 

 lip; gr, style; //', thickened edge of upper part of slit; w, nectary; oz/, ovary; 

 rr\ reflexed ed^e of lower part of slit in upper lip; st, stigma. 



side are unnecessary, and the anthers are consequently glabrous, while the longer 

 filaments are only sparsely beset with hairs. 



Warnstorf describes the pollen-grains as white in colour, tuberculate, about 

 31-5 ^ long and 25 \i. broad. 



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

 stated. — 



Lindman (Dovrefjeld), a humble-bee. Herm. Miiller (Alps), the humble-bee 

 Bombus pratorum L. j. Loew (Alps), the humble-bee Bombus alticola Krchb. 5, skg. 

 (' Beitrage,' p. 62). Heinsius (Holland), 2 humble-bees — Bombus agrorum F. 5, skg. 

 legitimately and regularly effecting pollination ; B. scrimshiranus K. ^, perforating the 

 flowers and stealing nectar (Bot. Jaarb. Dodonaea, Ghent, iv, 1892, pp. 109-11). 

 Scott-Elliot (Dumfriesshire), a humble-bee (' Flora of Dumfriesshire,' p. 133). Schulz, 

 the humble-bee Bombus terrester L., perforating the flowers and stealing nectar. 



