374 ANGIOSPERMAE—DICOTYLEDONES 



other Arctic species (Nos. 860, 872, and 889-891) rapidly set fruits, and are otherwise 

 well adapted to the conditions of life obtaining in high latitudes. Warming describes 

 them as probably homogamous, and relying upon automatic self-polhnation (of. Loew, 

 ' Bliitenbiol. Floristik,' p. 99). 



889. P. fragiformis Willd., var. parviflora Trautw. (the species=P. emargi- 

 nata Pursh, according to Abromeit, 'Bot. Ergeb. von Drygalski's Gronlandsexped.,' 

 p. 8). — In Spitzbergen this species is one of the earliest spring plants, and was 

 observed in flower 21. 6. '96, 30. 6/82, 1.7. '98, and 7. 7. '61. The last two dates apply 

 to North-east Land in 80° N. lat. Andersson and Hesselman state that abundant 

 fruits are set (' Bidrag till Kanned. om Spetsbergens o. Beeren Eil. Karlvaxtflora,' 

 pp. 19-20). 



The specimens which VanhofTen collected in Greenland and described as the 

 variety {a) typica (=P. emarginata Ptirsh) bear flowers 15-17 mm. in diameter, 

 with dark yellow petals traversed by darker veins. In the variety (c) ela/ior (=P. 

 fragiformis Willd.) the flowers are larger, their diameter being not infrequently 

 20 mm.: petals pale yellow, but darker and distinctly veined at their bases. The 

 development of the petals is clearly dependent upon oecological conditions. 



Ekstam says that this species and its variety parviflora are also native to 

 Nova Zemlia (Bot. Jahrb., Leipzig, xxii, 1897, p. 195). 



890. P. pulchella R. Br. — This species was found flowering in Spitzbergen 

 from June to the beginning of September, chiefly, however, in the second half of 

 July. Fruits are set and ripened in a normal way (Andersson and Hesselman, 

 'Bidrag till Kanned. om Spetsbergens o. Beeren Eil. Karlvaxtflora,' p. 19). Several 

 varieties of this species occur in Greenland (Abromeit, ' Bot. Ergeb. von Drygalski's 

 Gronlandsexped.,' pp. 7-8). 



891. P. nivea L. — This species was found flowering in Spitzbergen on 1 2. 7. '90, 

 and ripe fruits were collected on 6. 8. '82 (Andersson and Hesselman, op. cit., p. 20). 

 It is very polymorphous in Greenland. Here the yellow petals project but little 

 beyond the calyx : numerous fruits were noticed (Abromeit, op. cit., pp. 9-11). 



Visitors. — Lindman noticed a medium-sized fly on the Dovrefjeld. 



892. P. rupestris L. — This species, which was studied at Bozen by Schulz 

 (' Beitrage,' p. 68), is capable of automatic self-pollination, for the inner anthers 

 incline somewhat towards the middle of the flower, so as to be above the simul- 

 taneously mature stigmas upon which pollen can therefore fall. As but little nectar 

 is secreted, and the white flowers are not conspicuous, the number of insect-visits 

 is small. 



Visitors.— Schulz observed flies, beetles, and bees. MacLeod saw 5 Syrphids 

 and 5 Muscids (Bot. Jaarb. Dodonaea, Ghent, iii, 1891, p. 431). Loew noticed 

 Apis, skg., in the Berlin Botanic Garden. 



893. P. alba L. — The flower mechanism of this species agrees, according to 

 Kirchner (' Flora v. Stuttgart,' p. 447), with those of P. verna, P. opaca, and P. 

 Anserina. 



894. P. micrantha Ram. — In the flowers of this species, according to Kerner, 

 the stamens form a hollow cone which covers the nectar-secreting receptacle. 



