MALVACEAE 211 



Visitors. — Loew observed two bees in the Berlin Botanic Garden — Bombus 

 terrester L. S, skg. and dusting itself thickly with pollen, and Psithyrus vestalis 

 Fourcr. S, do. 



526. A. rosea Cav. (Kirchner, ' Flora v. Stuttgart,' p. 333 ; Knuth, ' Bloemen- 

 biol. Bijdragen.') — The very large white, yellow, red or blackish flowers of this well- 

 known ornamental plant are markedly protandrous. Their diameter is 6-7 cm. ; 

 each petal is about 4 cm. long, and 5-6 cm. broad above. Nectar is secreted by 

 five yellow areas at the bottom of the calyx, between the bases of the petals. It 

 is protected from rain and small insects by hairs on the petals. Automatic self- 

 pollination takes place if insect-visits fail, the stigmas curving back among the 

 anthers that have not yet lost all their pollen. 



Visitors. — I observed Apis mellifica L. and Bombus terrester L. Both sucked 

 persistently, although I was unable to taste the nectar. They flew from flower to 

 flower, skg. in each, and constantly effecting cross-pollination. Loew noticed the 

 same visitors in the Berlin Botanic Garden. 



Alfken observed the humble-bees Bombus hortorum L. S, and B. agrorum F. J, 

 skg., at Bremen. Rossler at Wiesbaden saw the Geometrid Ortholitha cervinata .S. V. 



For the Tyrol, Schletterer describes Bombus pascuorum Scop,, which is widely 

 distributed in South Europe. 



527. A. officinalis L. (Knuth, ' Bloemenbiol. Bijdragen.') — The flowers are 

 the same in structure as those of the last species, but considerably smaller, their 

 diameter being 2-3 cm., while the petals are 2 cm. long, and about as broad. 



Visitors. — In the Kiel Botanic Garden I observed the honey-bee and Bombus 

 terrester, skg. Schletterer describes the garden humble-bee for the Tyrol. 



528. A. cannabina L. — 



Visitors. — In the Botanic Garden at Berlin Loew observed the following. — 

 A. Diptera. Syrphidae: i. Eristalis nemonim Z., po-dvg. ; 2. E. tenax Z., do. 

 B. Hymenoptera. Apidae : 3. Apis mellifica Z. g, po-cltg. 



151. Hibiscus L. 



Protandrous pollen flowers. 



529. H. Trionum L. — The flowers of this species are yellow with a purple 

 base. Kerner (' Nat. Hist. PI.,' Eng. Ed. i, II, p. 212) says that they open between 

 8 a.m. and noon. The pollen-covered anthers rise up in the middle of the newly 

 opened flower, and the free parts of the filaments soon curve downwards so that 

 the stigmatic branches, as they become receptive, may occupy the place of the 

 anthers. Insect visitors must therefore effect cross-pollination. After a few hours 

 the styles become S-shaped, and curve downwards to such an extent that the 

 stigmatic papillae come into contact with the anthers, which are still covered with 

 pollen. 



152. Abutilon Toum. 



530. A. Avicennae DC. (= Sida Abutilon Z.). — Kerner states that the 

 flowers of this species open from 10 to 6 o'clock, and present the same arrangements 

 as those of Hibiscus Trionum. 



