198 



ANGIOSPERMAE—DICOTYLEDONES 



490. C. brachypetalum Desp. — According to Schuiz ('Beitrage,' I, pp. 51-2), 

 the number of stamens varies in this species, as in its allies. The stigmas are 

 receptive, even before anthesis. When the flowers open, contact between stigmas 

 and anthers very rarely, if ever, takes place. Automatic self-pollination regularly 

 occurs, however, when they close. Besides hermaphrodite flowers, female ones have 

 also been observed, distributed gynomonoeciously, more rarely gynodioeciously. 



Visitors. — Schuiz noticed two flies. Schletterer observed the two small bees 

 Andrena parvula K. and Halictus morio F. at Pola. 



491. C. tomentosum L. — Warming observed protandry, with transitions to 

 homogamy in cultivated plants. Automatic self-pollination takes place towards the 

 end of anthesis. 



492. C. viscosum L. — Batalin observed that in plants of this species developed 

 from seeds the flowers of the first summer often remained closed, while open flowers 

 were produced the following year. 



493. C. trigynum Vill. (= Stellaria cerastoides L). (Ricca, ' Oss. sulla fecondaz. 

 incroc. d. veget. alp. e subalp.'; Herm. Miiller, ' Alpenblumen,' pp. 188-9; Schuiz, 



Fig. 58. Cerasiium trigyntim^ Vill. (after Herm. Miiller). A. Section of a flower in the middle 

 of anthesis (X 7). B. Halfclosed flower in the act of automatic self-poilination. 



'Beitrage,' II, pp. 49-50.) — Hermann Miiller and Ricca describe the odorous flowers 

 as being homogamous, but Schuiz says that they are sometimes slightly protogynous 

 or protandrous. In sunny weather the anthers are so far from the stigmas that 

 insects alighting in the middle of the flowers effect cross-pollination. In cold, 

 dull weather the flowers hardly open at all, but in somewhat warmer cloudy weather 

 they do so rather more. Under such circumstances automatic self-pollination always 

 takes place. The styles vary in number from three to five. The stamens are 

 now and then vestigial. Schuiz states that the female flowers are distributed 

 gynomonoeciously, or more rarely gynodioeciously. 



On the Dovrefjeld also, according to Lindman, the flowers are homogamous 

 and autogamous, and here self-pollination takes place at the beginning of anthesis. 



