SCROPHULARINEAE 



183 



humble-bee Bombus hortorum L. $ and 5- The first two add that Bombus 

 terrester Z. 5 perforates the flowers and steals the nectar. 



2103. D. ambigua Murr. (=D. ochroleuca Jacq., and D. grandiflora Lam.). 

 (Herm. Miiller, ' Alpenblumen,' p. 275, 'Weit. Beob./ Ill, pp. 30-1; Kirchner, 

 'Flora V. Stuttgart,' pp. 585-6; Ludwig, Kosmos, Stuttgart, xvii, 1885; Schulz, 

 *Beitrage'; Loew, 'Bliitenbiol. Floristik,' p. 395.) The flower mechanism of this 

 species resembles that of D. purpurea. The corolla is dull yellow in colour, and 

 a network of brown lines on the inner surface of the lower lip serves as a nectar- 

 guide. The flower is so broad that humble-bees of any size can conveniently 

 creep into it and suck the nectar. Its entrance is 20-22 mm. broad and 12 mm. 

 high, so that even the smaller bees touch the anthers and stigma, and as protandry 

 is marked cross-pollination is ensured. The same end is further attained by the 

 fact that humble-bees are in the habit of working up the inflorescences from below. 



Fig. 392. Digitalis lutea, L. (after Herm. Muller). A. Flower in the first (male) stage, seen from 

 the side. B. Do., seen directly from the front. C. Do., after removal of most of the corolla, seen from 

 below. D. Pistil of do., seen from the side. E. Reproductive organs, during the dehiscence of the 

 anthers of the long stamens. F. Do., during the dehiscence of the anthers of the short stamens ; the two 

 short papillose stigmatic lobes are expanded (x 3 J), a, anthers of the long stamens ; , nectary. 



Should insect-visits fail, automatic self-pollination may possibly be effected by pollen 

 still clinging to the anthers. 



Besides hermaphrodite plants, Ludwig also observed small -flowered female 

 stocks with reduced vegetative organs, there being 2 % of these at Greiz and Plauen. 



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

 stated. 



Herm. Muller (Alps), a bee (Anthophora sp.) : (Kitzingen), 3 po-cltg. bees 

 I. Andrena coitana K.<^\ 2. Halictus sp. 5; 3. Dufourea vulgaris Schenck 5. 

 Herm. Muller, jun. (Alps), the humble-bee Bombus hortorum L. J. Loew (Alt- 

 vatergebirge and Silesia), the last-named humble-bee, % skg. ('Beitrage,' p. 52). 

 Schulz (Tyrol), the humble-bee Bombus terrester Z., skg. legitimately and also 

 perforating the flowers. Schletterer and von Dalla Torre (Tyrol), the humble-bee 

 Bombus pomorum Pz. $. 



