BORAGINEAE 



137 



Fig. 276. Lithospertnuin arvense, L. (after 

 Herm. Muller). (1) End of the style, taken from 

 a bud (x 36). St, stigma. (2) Position of the 

 reproductive organs in the flower. 



of the anthers, so that the entrance of the flower is completely filled, and the 

 proboscis of an insect probing for nectar must force its way between anthers 

 and stigma. If this takes place at the beginning of anthesis, and the proboscis 

 has previously been dusted with pollen, crossing will be effected, and a fresh 

 supply of pollen will adhere to the organ. Soon, however, the anthers dehisce 

 so strongly that the stigma gets covered with pollen, so that autogamy is inevitable. 

 Insect-visits are but few. 



Visitors. The following were recorded 

 by the observers, and for the localities 

 stated. 



Knuth, 2 bees (Apis mellifica L. 5, and 

 Bombus lapidarius Z. 5), skg., and a butter- 

 fly (Pieris brassicae Z.). Sprengel also 

 observed the 'common white butterfly.' 

 Herm. Muller. A. Diptera. Syrphidae: 

 I. Rhingia rostrata Z.; 2. Syritta pipiens Z. 

 B. Hymenoptera. Apidae : 3. Apis mel- 

 lifica Z. 5, skg. ; 4. Bombus agrorum Z. 5, 

 do. C. Lepidoptera. Rhopalocera-. all 

 skg. : 5. Pieris brassicae Z. ; 6. P. napi Z. ; 

 7. P. rapae Z. MacLeod (Flanders), a 

 Lepidopterid (Bot. Jaarb. Dodonaea, Ghent, 

 vi, 1894, p. 371). 



1996. L. canescens Lehm. Darwin describes the flowers of this species as 

 either heterostylous or very variable in regard to the length of the style. 



1997. L. purpurocaeruleum L, (Kirchner, 'Beitrage,' p. 51; Loew, 

 ' Bliitenbiol. Floristik,' p. 282.) The tolerably large flowers of this species exhibit 

 a similar colour change to that of Pulmonaria, being first purple-red and afterwards 

 blue. Kirchner found the plant to be feebly protogynous in the Swabian Alps, the 

 stigma being mature when the flowers opened, and the anthers dehiscing shortly 

 afterwards. Both organs stand at the same level just within the opening of the 

 cylindrical corolla-tube, 7 mm. above the base of the flower. Loew describes the 

 corolla-tube as 8-9 mm. long, with five radial white longitudinal folds at its 

 entrance corresponding to the hollow scales of some other genera. 



Visitors. Loew observed 2 long-tongued bees (Anthophora pilipes F. J, and 

 Osmia aenea Z.), skg., in the Berlin Botanic Garden. 



1998. L. officinale L. 



Visitors. Loew (Berlin Botanic Garden) observed the bee Megachile willugh- 

 biella K. 5, skg. ; and Schletterer (Pola) saw the bee Halictus variipes Mor. 



1999. L. angustifolium Michx. ( = Batschia longiflora Pursh). Darwin 

 observed cleistogamy in this species. 



615. Mertensia Roth. 



Flowers with concealed nectar. Dimorphous according to Darwin (' Different 

 Forms of Fls.'). 



