i86 ANGIOSPERMAE—DICOTYLEDONES 



and the stigmas, are not sharply demarcated. Failing insect-visits, automatic self- 

 pollination therefore takes place (see Fig. 55). Besides hermaphrodite flowers, Schulz 

 also observed female ones on gynodioecious, rarely on gynomonoecious plants. 



Visitors. — In the Alps, Herm. Muller only saw Diptera, i.e. 11 Muscidae, 

 3 Syrphidae, and an Empid. 



463. A. ciliata L. — Kirchner examined the hermaphrodite flowers at Zermatt 

 ('Beitrage,' p. 14). 



They are protandrous, and when fully expanded their diameter is 12 mm. 

 After the anthers have dehisced, the styles develop and the stigmatic papillae 

 mature. Besides hermaphrodite flowers, Kirchner also observed smaller female ones 

 with a diameter of 7-10 mm. The stamens of these are in various stages of 

 reduction : though all ten are sometimes present, all or most of them are quite short, 

 while some of them may be entirely absent. Ludwig (Bot. Centralbl., Cassel, iii, 

 1880, p. 102 1) first noticed the occurrence of female flowers on gynodioecious plants 

 in Switzerland ; Wanning found the species to be gynomonoecious in Norway 

 (' Om Caryophyll. blomst.,' 1890, pp. 32-3). 



Warming saw ripe fruits at Disko on the variety (b) humifusa Rink, the flowers 

 being slightly protandrous at first and afterwards homogamous. 



According to Andersson and Hesselman (' Bidrag till Kanned. om Spetsbergens 

 o. Beeren Eil. Karlvaxtflora,' p. 64), the variety frigida Koch flowers in Spitzbergen 

 from the beginning of July till August. Ekstam observed ripe fruits on August 7, 

 1897 (' Bliitenbiol. Beob. a. Spitzbergen,' p. 28). The pollen-grains are of two sizes ; 

 in one case there was 23% of small grains. The flowers are very fragrant; 

 Ekstam gives their diameter as 11- 14 mm. In flowers not fully open the stigmas 

 already possess glistening papillae, while the anthers are still undehisced. When 

 the flowers are quite expanded autogamy takes place, for the dehiscing anthers 

 come into contact with the stigmas by bending of the filaments. Nectar is secreted 

 on the outer sides of the stamens superposed to the sepals. 



Visitors. — On one occasion Ekstam observed a small fly in Spitzbergen. 



464. A. graminifolia Schrad. — 



Visitors. — Loew observed a Syrphid — Eristalis nemorum L. — and two bees — 

 Apis mellifica L. 5, skg., and Prosopis communis Nyl. S, po-dvg. — in the Berlin 

 Botanic Garden. 



465. A. arctica Stev. — This species is native to Siberia and Alaska. 

 According to Alice Eastwood (Bot. Gaz., Chicago (111.), xxxiii, 1902, pp. 137-8), 

 the petals are over 7 mm. long and 5 mm. wide, with short yellow claws. The 

 filaments thicken abruptly at their bases, so that there is perhaps a secretion of nectar. 



135. Holosteum L. 



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

 concealed nectar. 



466. H. umbellatum. (Herm. Muller, ' Weit. Beob.,' II, pp. 226-7; Schulz, 

 ' Beitrage,' II, pp. 48-9 ; Warnstorf, Verb. natw. Ver., Berlin, xxxviii, 1896; Schr. 

 natw. Ver., Wernigerode, xi, 1896.) — According to Herm. Muller, the small white 

 flowers are protandrous, and cross-pollinated by insect-visits, though automatic self- 



