524 



ANGIOSPERMAEDICOTYLEDONES 



stigmas, in Wurtemberg ; but in the South Tyrol, according to Schulz, there is 

 variation between protogyny, homogamy, and slight protandry. Kerner says that 

 their odour suggests herring-brine (trimethylamide), while Kirchner describes it as 

 meal-like. The latter also states that, after the flowers have opened, the tips of the 

 petals sometimes bend right back, and the stamens diverge so much as to be almost 

 in one plane ; their anthers, however, are still unripe, while the three short stigmas 

 are fully mature. The tips of the petals then grow to some extent, and assume 

 a yellowish colour; the anthers dehisce downwards and outwards, the stigmas 

 remaining receptive. All the flowers of an inflorescence, at a given time, are in about 

 the same stage of anthesis. As the inflorescences are of more inconspicuous greenish 

 colour in the first (female) than in the second (hermaphrodite) stage, flowers in the 

 latter condition are usually first visited by insects, which afterwards transfer the pollen 

 to those in the female stage. In the second stage automatic self- and cross-pollination 

 are both possible, for the numerous flowers are turned in all directions. Kerner 

 describes geitonogamy as taking place in the later stages of anthesis by elongation 

 and bending of the filaments, so that pollen is applied to the stigmas of neighbouring 

 flowers. 



Visitors. Redtenbacher (Vienna) noticed 2 Cerambycid beetles Leptura 

 virens Z., and Strangalia quadrifasciata L. 



xaii. S. australis Cham, et Schlecht. K. Mailer describes this species as 

 gynodioecious (Ber. D. bot. Ges., Berlin, ii, 1884). 



386. Viburnum L. 



Flowers white in colour, possessing an odour of amide ; arranged in umbellate 

 cymes ; homogamous ; with exposed to half-concealed nectar, secreted in a flat layer 



on the upper surface of the 

 ovary, immediately below 

 the stigmas, in the base of 

 the flower. 



iaia. V. Opulus L. 

 (Sprengel, 'Entd. Geh.,' p. 

 1 59 ; Herm. Mttller, Fertili- 

 sation,' pp. 291-2, 'Weit. 

 Beob.,' Ill, pp. 75-6 ; Knuth. 

 ' Bloemenbiol. Bijdragen.') 

 Sprengel clearly explained 

 how the large marginal 

 neuter flowers serve to render 

 the whole inflorescence more 

 conspicuous in this species. 



Hermann Mttller de- 

 scribes the hermaphrodite 

 flowers as homogamous. The diverging stamens project from them, and their anthers 

 are covered with pollen all round, affording abundant booty to pollen-collecting 

 bees, while the flat layer of nectar only attracts flies and other short-tongued insects. 



Fig. 171. Viburnum Opulus, L. (after Herm. Mttller}. (i) Mar- 

 ginal flower seen from above, showing the vestiges of anthers and 

 stigma (x a,), (a) Fertile flower, soon after opening, seen obliquely 

 from above ( x 4i). (3) Ditto, after removal of the anterior petals and 

 stamens (x 4I). 





