CONVOLVULACEAE 149 



that it takes place later on, for the stamens elongate so that the two or three longest 

 touch the stigma. Kerner adds that it is in any case inevitable, for when the corolla 

 withers it rolls up and presses the anthers against the stigma. 



2018. I. Pes-tigridis L. (Dillenius, Bot. Ztg., Leipzig, xxi, 1863, p. 310.) — 

 This species bears cleistogamous flowers. 



620. Cuscuta L. 



Small inconspicuous flowers, aggregated into clusters or spikes ; usually homo- 

 gamous ; with concealed nectar, secreted by the base of the ovary. Kerner says that 

 autogamy is brought about by convergence of the filaments. Cleistogamy frequent. 



2019. C. Epithymum Murr. (including C. trifolii Bab.). (Herm. Miiller, ' Weit. 

 Beob.,' Ill, pp. 7-8; MacLeod, Bot. Jaarb. Dodonaea, Ghent, v, 1893, p. 330; Kirchner, 

 ' Flora v. Stuttgart,' p. 550 ; Warnstorf, Verb. bot. Ver., Berlin, xxxviii, 1896 ; Knuth, 

 ' Bl. u. Insekt. a. d. nordfr. Ins.,' pp. 106-7.) — The flowers of this species are whitish 

 or reddish, and usually pentamerous, though in some cases 4-, 3-, or 2-merous. The 

 nectar is protected from rain by five or a smaller number of scales which bend 

 together over the ovary. The lobes of the corolla are at first directed obliquely 

 upwards, but subsequently spread out horizontally. The stamens mature at the 

 same time as the stigmas, and are considerably longer than the two styles (especially 

 in the variety trifolii Bab.). The latter are generally irregularly curved, and their 

 upper stigmatic region is of a purple colour. Cross-pollination by means of insects 

 is favoured, for anthers and stigmas are generally touched by opposite sides of their 

 proboscis. But autogamy is easy should insect-visits fail, for the stigmas lie in the 

 line of fall of the pollen. 



Warnstorf describes the whitish or reddish flowers as feebly protandrous. The 

 yellow anthers are brown at the side and dehisce laterally before the purple stigmatic 

 branches attain their full maturity and project from the open corolla, while at the 

 same time the stamens and corolla-lobes curve outwards. Autogamy is thus at any 

 rate rendered very difficult. The pollen-grains are of golden-yellow colour, ellipsoidal, 

 closely tuberculate, up to 31 /x long and 18-20 yu. broad. 



The flowers of plants observed by me in the island of Amrum opened slightly 

 or not all ; the automatic self-pollination which took place was followed by the 

 setting of abundant fruits. 



Visitors. — The following were recorded by the observers, and for the localities 

 stated. — 



Herm. Miiller, 2 fossorial wasps — Crabro elongatus v. d. L., occasional, skg., 

 and Philanthus triangulum F. S, freq., skg. Kohl (Tyrol), the true wasp Polistes 

 gallica L. 



2020. C. europaea ( =C. major Gilib.). (Kirchner, ' Flora v. Stuttgart,' p. 550 ; 

 Cosson et Germain, 'Atlas flore,' pi. XIV, Paris, 1882; MacLeod, Bot. Jaarb. 

 Dodonaea, Ghent, v, 1893, pp. 330-1; Kerner, 'Nat. Hist. PI.,' Eng. Ed. 1, II, 

 391; Warnstorf, Verh. bot. Ver., Berlin, xxxviii, 1896.) — The flowers of this 

 species are usually reddish in colour, and, though somewhat larger than those of 

 the last species, Kirchner describes their mechanism as similar. Kerner found 



