LEGUMINOSAE 



269 



A. Araneidae. 1. Philodromus aureolus Clerck, lurking on unexploded flowers 

 and the central parts of exploded ones. B. Coleoptera. 2. Apion ulicis Forst.; 

 3. Meligethes picipes Sturm, po-dvg. ; 4. Cryptophagus vini Panz., po-dvg. and 

 searching for nectar. C. Diptera. (a) Muscidae: 5. Hylemia sp., searching for 

 nectar; 6. Lucilia cornicina F., do.; 7. Sepsis nigripes Mg., do. (b) Syrphidae: 

 8. Eristalis arbustorum Z., po-dvg. ; 9. E. pertinax Scop., searching for nectar ; 



10. Melanostoma quadrimaculata Verral, po-dvg. D. Hymenoptera. Apidae'. 



11. Andrena clarkella K., po-cltg. ; 12. Apis mellifica Z. $j, po-cltg. and at times 

 searching for nectar; 13. Bombus lapidarius Z., searching for nectar; 14. B. ter- 

 rester Z., do. and po-cltg. E. Thysanoptera. 15. Thrips sp., very freq. 



197. Cytisus L. 



Yellow, homogamous to protandrous, monadelphous bee flowers; with sap 

 enclosed in the tissues of the base of the flower, requiring to be bored for. The 

 pressure exerted by a visitor causes stamens and pistil to protrude from the carina, 

 to which they return when the pressure ceases. Several effective visits are therefore 

 possible. In some species there is a transition to a pumping arrangement. (Cf. 

 C. nigricans.) 



647. C. Laburnum L. (Herm. Muller, 'Fertilisation,' pp. 193-5; Kirchner, 

 I Flora v. Stuttgart/ pp. 475-6; Knuth, ' Bloemenbiol. Bijdragen.') The flowers of this 

 species are of considerable size, 

 and aggregated into conspicuous 

 many-blossomed inflorescences. 

 Kerner says that when they open 

 the pedicels twist round so as 

 to turn the vexillum upwards 

 and the carina downwards. 

 The insertion of the vexillum 

 is bounded in front by a thick 

 fleshy swelling, full of sweet sap. 

 As nectar-guides, the. vexillum 

 possesses dark streaks, con- 

 verging basally to this swelling, 

 from which nectar is obtained 

 by boring. The union of alae 

 and carina is but slight, and is 



effected by a flattish alar projection, which fits into a corresponding carinal pit 

 on either side. 



Towards the end of the bud-period the stigma lies in the tip of the carina, 

 surrounded by stiff, glassy, erect hairs, that project beyond it, and at the beginning 

 of anthesis bend somewhat over its papillae, which are thus guarded from contact 

 with the under-sides of insect visitors. These hairs gradually shrivel up, so that 

 in older flowers the papillae are quite uncovered. At the same time the style curls 

 more and more inwards, and stretches out to an increasing distance through the 

 open cleft of the carina, so that insect visitors first touch the stigma, and cross - 

 pollination is ensured. Automatic self-pollination is excluded. 



Fig. 86. Cytisus Laburnum, L. (after Herm..MulIer). (i) Basal 

 part of an older flower, after removal of calyx and vexillum ; seen 

 from above: aa, cut surface of calyx ; b, insertion of vexillum ; c, the 

 nectar-yielding swelling, into which insects appear to bore; rf, claw 

 of ala ; e, flat projection of ala, which fits into a corresponding pit 

 on the upper side of the carina ; f, carina ; g, open slit of the same. 

 (2, 3, 4) Stigmas of younger flowers. (5 ) Stigma of an older flower. 



