228 



ANGIOSPERMAE—DICOTYLEDONES 



Visitors. — Herm. Muller saw 

 the Alps. 



2 hover-flies, 3 bees, and 7 Lepidoptera in 



nectary is (Loew, 



2175. E. lutea L. (= Odontites lutea Reichb.). (Herm. Muller, 'Fertilisation,' 

 p. 447; Kirchner, 'Flora v. Stuttgart,' p. 602.) — This species bears golden-yellow 

 flowers belonging to class CH ; with a corolla-tube only 2-| mm. long, which is 

 glabrous on the inner side, but beset with small vertical hairs at the entrance, that 

 serve as nectar-covers. The four stamens are remote, but owing to the smallness of 

 the flower they are all touched simultaneously by insect visitors. Hermann Muller 

 says that the flowers are homogamous, though sometimes the style is widely exserted 

 even in the bud ; in other cases it protrudes simultaneously with the anthers. Since 

 the stigma is situated under, and in front of the anthers, it is first touched by insect 

 visitors and dusted with foreign pollen. Should such visits fail, automatic self- 

 pollination generally occurs by the falling of pollen on the stigma. 



Kemer states that the flower mechanism resembles that of Tozzia. The 

 Blutenbiol. Floristik,' p. 297) a longitudinal groove in the 

 base of the ovary. The filaments 

 are strongly bent ; the anthers are 

 separate, not bound together by 

 hairs, and provided with a little 

 point directed downwards. In pro- 

 togynous flowers the already recep- 

 tive stigma is situated at first in 

 front of the still narrow entrance, 

 and as the anthers are still unripe 

 self-pollination is excluded. In the 

 second stage of anthesis the corolla 

 opens more widely, resembling a 

 Veronica flower. The filaments elongate considerably at the same time, twisting in 

 various ways, and the anthers turn round. The style, however, bends downwards, 

 so that the stigma is pushed under the entrance of the flower, and cannot be 

 brushed against by insects as they enter. In the third stage, the filaments also bend 

 downwards, but the style once more bends upwards, so that the slightest shaking 

 causes pollen to fall on the stigma. 



Visitors. — Herm. Muller observed the humble-bee Bombus agrorum F. 5, skg. 



2176. E. minima Jacq. (= E. officinalis Z., according to the Index Kewensis). 

 (Herm. Muller, ' Alpenblumen,' pp. 281-3; Kemer, 'Nat. Hist. PI.,' Eng. Ed. i, 

 II. 353; Schulz, ' Beitrage,' 11, pp. 124-5.) — This species bears yellow flowers 

 belonging to class CH. Hermann Muller says that they essentially resemble those 

 of the small-flowered form of E. officinalis as regards their mechanism and the course 

 of their development. Cross-pollination by means of insect-visits is ensured by the 

 prominent position of the stigma at an early stage. If such visits fail, the style 

 elongates and bends down under the anthers, so that pollen falls on the stigma, and 

 automatic self-pollination is eff"ected. 



Schulz states that in most cases the stigma is already fully matured in the bud, 

 lying under the upper and even under the lower anthers, and generally reaching up 



KiG. 320. Euphrasia lutea, L. (after Herm. Miiller). 

 <i) Flower, seen from the side. (2) Do., directly from the 



front. (3) Bud, seen from the side (x 34). (4) Stamen. 



