SAPINDACEAE 257 



are considerably shorter than those of male flowers, in which they are so long that 

 the anthers about reach the tips of the petals : they surround a vestigial pistil. After 

 fertilization the female flowers close, the sepals and petals becoming erect. Warnstorf 

 describes the pollen-grains as pale yellow in colour, ellipsoidal, with three longitudinal 

 grooves, very delicately striated, about 50 /* long and 20 //. broad. 

 Visitors. Herm. Muller observed the honey-bee. 



632. A. campestre L. The greenish flowers of this species open at the 

 same time that the leaves unfold, they are much less conspicuous than those of 

 A. platanoides, with which, according to Wittrock, they entirely correspond as regards 

 mechanism and distribution of sexes. 



Visitors. Alfken observed 3 Apidae at Bremen : 1. Andrena nigro-aenea K. 5 ; 



2. A. trimmerana K. <j> ; 3. Apis mellifica Z. ijf. 



H. de Vries saw Apis mellifica Z. $j, freq., in the Netherlands (Ned. Kruidk. 

 Ach., Nijmegen, 2. ser., 2. deel, 1875). 



633. A. Pseudo-Platanus L. This species does not blossom till the leaves 

 have unfolded. Wittrock states that the flowers agree essentially with those of 

 A. platanoides, except that purely male or purely female inflorescences have not so 

 far been observed. According to Jordan, there is a nectar-cover, in the form of 

 white hairs at the bases of the stamens. 



Warnstorf (Schr. natw. Ver., Wernigerode, xi, 1896) gives the following 

 account. Inflorescence a racemose panicle ; flowers markedly protandrous. Lower 

 floral axes branched, with male and pseudo-hermaphrodite fruiting-flowers ; the 

 middle ones being either almost purely female, and the upper ones mixed male and 

 female, or the former mixed female and male, and the latter purely female. The 

 filaments of the male flowers project far beyond the petals, while those of the female 

 flowers are very short, and do not exceed the petals in length. 



Visitors. Herm. Muller observed the following. 



A. Diptera. Syrphidae: 1. Eristalis arbustorum Z., skg. ; 2. E. tenax Z., do. ; 



3. Syrphus ribesii Z., po-dvg. B. Hymenoptera. Apidae : 4. Andrena albicans 

 Mull. 5, skg. ; 5. Anthophora aestivalis Pz. 5, do. ; 6. Bombus hortorum Z. 5, do. ; 

 7. B. lapidarius Z. 5, do.; 8. B. rajellus K. $>, do.; 9. B. terrester Z. $, do.; 10. 

 Melecta luctuosa Scop, j, do.; 11. Osmia emarginata Lep. 5, do.; 12. Psithyrus bar- 

 butellus K. $, do. 



Loew noticed the following in the Berlin Botanic Garden. 



A. Diptera. Bibionidae: 1. Bibio hortulanus Z. 5, skg. B. Hymenoptera. 



Apidae: 2. Apis mellifica Z., skg. 



Friese saw the following Apidae in Hungary. 1. Andrena bucephala S/ph., 

 freq. ; 2. A. gwynana K., 2nd generation ; 3. A. mitis Per. ; 4. A. rufula P/r. ; 5. A. 

 trimmerana Z\ ; 6. Nomada alternata K. ; 7. N. bifida Ths.; 8. N. ruficornisZ. ; 

 9. N. succincta Pz. 



634. A. dasycarpum Ehrh. In this North American species, occasionally 

 cultivated in Europe, the flowers are arranged in dense clustered inflorescences, and 

 open long before the leaves unfold. Kirchner ('Flora v. Stuttgart,' p. 352) says that 

 the diameter of the male flowers is only about 2 mm. The stamens project 6 mm. 

 from the calyx, which is yellowish with a reddish margin, and 4 mm. long. No 

 pistil is visible. The female flowers are compressed like the ovary; the calyx is 



