RANUNCULACEAE 15 



MacLeod, Bot. Jaarb. Dodonaea, Ghent, vi, 1896, pp. 173-4; Knuth, 'Bl. u. 

 Insekt. a. d. nordfr. Ins.,' p. 17; Kirchner, 'Flora v. Stuttgart,' p. 262.) — When 

 the flower opens, the slender terminal lobes of the petals are directed outwards, and 

 each secretes in a shallow pit a drop of nectar that is at once visible. The stamens, 

 which are closely pressed against the carpellary cone, dehisce laterally by longitudinal 

 slits, so that their outer surfaces become completely covered with pollen. The small 

 visitors — minute flies and midges — get dusted with pollen below while licking the 

 nectar, and creeping about upon the central cone, transfer pollen from the same or 

 another flower to the stigmas. In young blossoms, where the carpels make up 

 a rounded projection, or at most a short cone, the visitors — according to Miiller — 

 usually alight upon its apex, thus effecting cross-pollination. As, however, owing to 

 the inconspicuousness of the flower, insect-visits are very few, automatic self-pollina- 

 tion takes place to a very great extent. For as the flower gets older, its axis — closely 

 beset with carpels — increases greatly in length, so that fresh stigmas are continually 

 being brought to the closely apposed anthers, and are pollinated in regular succession. 

 According to Warnstorf (Verh. bot. Ver., Berlin, xxxviii, 1896), in some 

 just-opened flowers, the cone formed by the gynoecium is lower than the stamens 

 which cover it and the stigmas are already mature when the pollen is ripe, hence 

 these flowers are homogamous and autogamous. In other cases, the carpellary cone 

 is elongated and projects from the flower before it opens, and as the stigmas are not 

 mature at this stage, while some of the anthers of the deeply-placed stamens have 

 already dehisced, such flowers are decidedly protandrous. Self-pollination of the 

 central stigmas is in this case precluded, though it may take place in the lower 

 stigmas by further elongation of the axis bearing the carpels. 



Visitors. — On the island of Fohr I noticed tiny Muscidae, but did not 

 determine their species. Hermann Miiller observed the following at Lippstadt. — 

 Diptera. (a) Bibionidae: i. Scatopse brevicornis jl/g'. (b) Cecidomyidae: 2. Ceci- 

 domyia sp. {c) Chironomidae : 3. Chironomus byssinus Schr. and other sp. 

 (d) Empidae: 4. Microphorus sp. (e) Muscidae: 5. Anthomyia sp., several cases. 

 6. Hydrellia chrysostoma Mg. 7. H. griseola Fallen. 8. Oscinis sp. (/") Myceto- 

 philidae: 9. Sciara sp., 2 sp. in 7 cases. {g) Phoridae: 10. Phora sp. (h) 

 Syrphidae: 11. Melanostoma mellina L., a single case. 



9. Batrachium S. F. Gray 



Flowers homogamous or slightly protogynous or protandrous, with half-con- 

 cealed nectar. The white petals which serve for attraction are usually ornamented 

 at the base with a yellow nectar-guide. Honey is secreted in a pit (open in several 

 northern species, according to Almqvist) at the base of each of them. The stem creeps 

 in mud or floats in water, so that the flowers are accessible only to flying insects and 

 not to creeping ones. 



34. B. hederaceum S. F. Gray ( = Ranunculus hederaceus Z.). (Knuth, 'Bl. 

 u. Insekt. a. d. nordfr. Ins.,' pp. 17-18, 147.)— The diameter of the homogamous 

 flowers is only 4-5 mm. Nectar is sparingly secreted. The 8-10 stamens are in a 

 single whorl, and since they are at the same level as the stigmas, and mature simul- 

 taneously, self-pollination must take place should insect-visits fail. This happens 

 very frequently, for, owing to the inconspicuousness of the flower, such visits are 



