156 ANGIOSPERMAEDICOTYLEDONES 



always touched by the under-side of visitors, so that the upper anthers have 

 scarcely anything to do with cross-pollination, but on the other hand are useful 

 for autogamy, which may take place, as a last resort, by the fall of pollen, 

 should insect-visits fail. 



Warnstorf describes the pollen-grains as white in colour, rounded polyhedral, 

 beset with lines of delicate papillae, and on an average 50 fx. in diameter. 



Kerner has observed a change of position between the anthers and stigma, the 

 latter occupying the middle of the flower in the first change of anthesis, while the 

 unripe anthers are apposed to the corolla. During the second stage these positions 

 are reversed. I have examined the flowers to see whether this is actually the case, 

 but am not able to confirm Kerner's description. Kerner adds that the style falls off 

 and the corolla withers an hour after pollination. 



Visitors. Buddeberg gives the following list for Nassau. 



A. Hymenoptera, Apidae: all skg. : i. Andrena gwynana if. 5; 2. Antho- 

 phora furcata Pz. 5; 3. Apis mellifica L. 5^, numerous; 2. Bombus pratorum Z., 

 very common ; 5. Cilissa leporina Pz. S ; 6. Halictus cylindricus F. 5, freq. ; 7. H. 

 leucopus K. 5, in large numbers ; 8. H. malachurus K. 5, very numerous ; 9. Mega- 

 chile centuncularis L. $, in large numbers, po-cltg. B. Thysanoptera. 10. Thrips, 

 numerous, penetrating to the nectar. 



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



Knuth, the honey-bee and 2 humble-bees Bombus agrorum F. 5. and B. 

 terrester Z. 5, both skg. Herm. Miiller (Miinster), the honey-bee, skg., and 

 Thrips. Loew (Berlin Botanic Garden), 2 humble-bees Bombus lapidarius Z. J. 

 and B. terrester Z. 5, both skg. Plateau (Ghent), the honey-bee. 



630. Mandragora L. 



Flowers protogynous ; with concealed nectar, secreted at the base of the ovary. 



2031. M. officinarum L. (=M. vernalis BertoL). (Hildebrand, 'D. Geschlechts- 

 Vert. b. d. Pfl.' ; Loew, ' Blutenbiol. Floristik,' p. 265 ; Kerner, ' Nat. Hist. PI.,' Eng. 

 Ed. I, II, p. 279.) In this Mediterranean species the flowers smell like nightshade 

 and are directed upwards. Kerner says that the lobes of the corolla close together 

 at night and during rainy weather. The flowers lie close to the ground. Loew 

 describes the corolla as of a dull-bluish colour inside, beset with peculiar glandular 

 villous projections and veined with yellow-green externally. The nectar is protected 

 from unbidden guests by thick tufts of hair above the bases of the filaments. Kerner 

 says that a change of position takes place between the stigma and anthers. At first 

 the former occupies the centre of the flower, while the stamens with the unripe 

 anthers lie against the corolla. Two days later the style has bent to the side, 

 bringing the stigma to the corolla, while the stamens Avith their pollen-covered 

 anthers now occupy the middle of the flower. {Cf. Hyoscyamus, Atropa, an 

 Scopolia.) 



Visitors. Loew saw the honey-bee, po-cltg., in the Berlin Botanic Garden 

 ('Beitrage,'II,p. 48). _ 



631. lochroma Benth. V 



22032. I. tubulosa Benth. (Delpino, * Altri appar. dicog. recent, oss.,* p. 60.) 

 Delpino describes this Mexican species as protogynous, with persistent stigmas. 



I 



