CRASSULACEAE 



427 



Loew observed the following visitors in the Berlin Botanic Garden. 

 A. Diptera. Syrphidae: 1. Syritta pipiens L. B. Hymenoptera. Apidae: 

 2. Apis mellifica L. 5, skg. ; 3. Bombus sylvarum L. 5, do.; 4. B. terrester Z. $, do. 



1003. S. dasyphyllum L. (Schulz, 'Beitrage,' II, pp. 77-8.) The flowers 

 of this species are white with a reddish tinge. Schulz describes them as protandrous, 

 to a degree inversely proportional to the height of the habitat above sea-level : 

 the plants of low-lying districts are most markedly so. In such places (e. g. in the 

 Etschthal) the styles with their immature stigmas lie close together at the time 

 when the flower opens : the stigmas only become receptive when the anthers have 

 shed all their pollen, often indeed, only when they have dropped off: it follows 

 that self-pollination is almost entirely excluded. In higher regions (e.g. the Ortler 

 district), the stigmas ripen somewhat sooner, so that automatic self-pollination is 

 usually tolerably easy when they spread out. 



Kerner states that the stigmas are receptive when the flower opens ; and that 

 the outer stamens serve for cross-, the inner ones for self-pollination. It appears, 

 therefore, that homogamy also obtains. 



Fig. 144. Sedutn album, L. (after Herm. Miiller). A. Just opened flower. B. Flower in the second 

 half of the first (male) stage. C. Flower in the second (female) stage. D. Centre of the flower, after 

 removal of the carpels. ( x 7.) a, anther ; fi, filament ; n , nectary ; A petal ; s, sepal ; st, stigma. 



The nectaries are small, heart-shaped, stalked scales, yellow or orange-red 

 in colour, and placed opposite the ovaries. 



Visitors. Schulz observed numerous short-tongued insects (flies and the 

 smaller Hymenoptera), but does not record their species. MacLeod saw a bee 

 in the Pyrenees (Bot. Jaarb. Dodonaea, Ghent, iii, 1891, p. 418). 



1004. S. altissimum Poir. (=S. nicaee'nse All.) The flowers of this species 

 are yellow. 



Visitors. MacLeod saw a bee (Halictus morio) in the Pyrenees. 



1005. S. album L. (Herm. Miiller, 'Weit. Beob.,' I, p. 296, ' Alpenblumen,' 

 pp. 80-1 ; Schulz, 'Beitrage,' I, p. 77 ; Loew, 'Bliitenbiol. Floristik,' p. 397.) The 

 flowers of this species are distinctly protandrous, and Hermann Miiller says that 

 self-pollination is scarcely possible. Schulz confirms this statement for the Tyrol. 

 (Cf. Fig. 144.) 



Visitors. Herm. Miiller (Alps) saw 3 beetles, 7 flies, 2 bees, and 3 Lepidoptera. 



