OLE ACE AE 



83 



555. Syringa L. 



Flowers homogamous, rarely protandrous or protogynous ; aggregated into 

 large conspicuous inflorescences; with concealed nectar, secreted in the base of 

 the corolla-tube by the ovary. 



1847. S. vulgaris L. (Sprengel, 'Entd. Geh./ pp. 47-8; Herm. MuUer, 

 'Fertilisation,' pp. 392-3, 'Weit. Beob.,' Ill, p. 62 ; Kirchner, 'Flora v. Stuttgart,' 

 P- 537 ; Warnstorf, Schr. natw. Ver., Wernigerode, xi, 1896 ; Knuth, ' Bl. u. Insekt. 

 a. d. nordfr. Ins.,' pp. 103, 164.) — The flowers of this species, and also those of the 

 two following ones, are bluish-lilac, rarely white in colour, fragrant, and aggregated 

 into large conspicuous inflorescences. They are usually homogamous, more rarely 

 protandrous or protogynous ac- 

 cording to Batalin (Bot. Ztg., 

 Leipzig, xxviii, 1870, pp. 54-5). 

 The corolla-tube is 8-10 mm. long 

 and about 2 mm. in diameter. 

 Its lower part is filled for 2-4 mm. 

 by the nectar which the ovary 

 secretes abundantly. The anthers 

 are situated in the entrance of 

 the flower at a higher level than 

 the stigma, so that the proboscis 

 of an insect-visitor will first touch 

 the former and then the latter. 

 This does not result, however, in 

 self-pollination of the homogamous 

 flowers, the reason being that pollen 

 does not adhere to the proboscis 



when it is pushed in, but only during withdrawal, after it has been moistened with 

 nectar. Insects which suck nectar will therefore regularly effect crossing, but those 

 which devour pollen always bring about autogamy. Should insect-visits fail, the 

 latter takes place automatically by fall of pollen upon the stigma. Kerner says that 

 during the early days of anthesis autogamy is rendered difficult because the anthers 

 are turned outwards, but when they shrivel later on it can easily take place. 



Warnstorf describes the pollen-grains as yellow in colour, more or less ellip- 

 soidal, longitudinally furrowed, closely beset with a network of tubercles, up to 50 ^ 

 long and 30 ^ broad. 



Visitors. — Herm. Muller gives the following list for Westphalia. — 



A. Diptera. {a) Bombyliidae: i. Bombylius major Z., skg. (b) Syrphidae: 

 2. Eristalis arbustorum Z., po-dvg. ; 3. E. sepulcralis Z., po-dvg. ; 4. Rhingia rostrata 

 Z., extremely frequent, skg. and po-dvg. ; 5. Syritta pipiens Z., po-dvg. ; 6. Xylota 

 segnis Z., vainly trying to suck, and then po-dvg. B. Hymenoptera. (a) Apidae : 

 7. Anthophora pilipes F. $ and S, freq., skg. ; 8. Apis mellifica Z. 5, numerous, skg. 

 and po-dvg. ; it pauses in its flight, without settling, before different flowers, until one 

 in a suitable condition is found. 9. Bombus hortorum Z. 5 and $, very numerous, skg. ; 

 10. B. lapidarius Z. 5 and j, numerous, skg.; 11. B. terresler Z. 5 and 5, skg.; 

 12. Eucera longicornis Z. 5, do.; 13. Halictus albipes F. 5, do.; 14. Osmia rufa Z. 



Fig. 252. Syringa •vulgaris^ Z-. (after Herm. Miiller). 

 (I) Flower after removal of half the corolla. (2) Flower 

 seen from above. (3) Entrance of a flower immediately 

 after opening. (4) Do., rather later. a, anthers; 7?, fila- 

 ments ; ov, ovary ; /, petals ; po, pollen ; j, sepals ; st, stigma. 



