SAXIFRAGEAE 



397 



939. S, mutata L. — The flowers of this species secrete exposed nectar, and 

 Stadler describes them as protandrous, though self-pollination is not excluded. The 

 stamens at first move towards the centre, and later on away from it. 



940. S. Burseriana L. — Kerner states that the flowers of this species are 

 protogynous, but during the twelve days of anthesis the stamens move towards 

 the centre, so that automatic self-poUination ultimately takes place. 



941. S. caesia L. (Herm. Miiller, ' Alpenblumen,' pp. 102-4; Engler, Bot. 

 Ztg., Leipzig, xxvi, 1868.) — The blossoms of this species are fly flowers, secreting 

 exposed nectar. Engler was the first to notice their protandry. Self-pollination 

 is entirely prevented in the Alps. 



Visitors. — These are chiefly flies, of which Herm. Miiller observed 15 species 

 in three days, besides 3 beetles, 3 Hymenoptera, and 3 Lepidoptera. 



B.~j 



Fig. 125. Saxi/raga caesia, L. (after Herm. Miiller). A. Flower in the first (male) stage (X4s). 

 B. Flower in the middle of the same stage. C. Flower in the second (female) stage. 1-6, anthers ; 

 ^.filaments; 7Z, nectary; (7Z', ovules; ^, petals ; .f, sepal; .s/, stigma. 



942. S. exarata Vill. (=S. nervosa Lapeyr.). (Herm. Miiller, 'Alpenblumen,' 

 p. 104.) — The blossoms of this species are fly flowers secreting exposed nectar. 

 Their mechanism essentially agrees with that of S. caesia. Here again self-pollination 

 is prevented (in the Alps) by well-marked protandry. 



Visitors. — Herm. Miiller observed 4 species of flies and an ant. MacLeod 

 saw a fossorial wasp and a hover-fly in the Pyrenees. 



943. S. oppositifolia L. (Ricca, Atti Soc. ital. sc. nat., Milano, xiv, 1871; 

 Warming, Bot. Tids., Kjobenhavn, xvi, 1888, pp. 29-33, ^^f- -^k. Overs., Kjoben- 

 havn, 1886-7, p. 13; Herm. Miiller, 'Alpenblumen,' pp. 98-100.) — The flowers of 

 this species are variously described by Engler as protandrous, Axell as slightly 

 protandrous, Ricca as homogamous, and Hermann Miiller as protogynous (on the 

 Piz Umbrail and the Albula). Schulz also observed protogyny, as did Warming 

 in Greenland, and Lindman on the Dovrefjeld. Ekstam, on the other hand, noticed 

 protandry in Nova Zemlia. The blossoms are Lepidopterid flowers with concealed 

 nectar. Lindman observed large-flowered and small-flowered varieties on the Dovre- 

 fjeld. Failing insect-visits, self-pollination frequently takes place, and appears to 

 be effective, for the flowers in Greenland set many fruits, despite the early anthesis 

 and the lack of insects. Lindman also observed ripe fruits on the Dovreljeld, 

 but no visitors. 



