20 ANGIOSPERMAEDICOTYLEDONES 



five grey anthers are 6 mm. long and borne on bluish-white filaments, 3 mm. long 

 and broadened at their bases. They dehisce when the bud is fully mature and 

 deposit their grey pollen on the hairs covering the style. In the open flower the 

 stamens have shrivelled, and the pollen-laden style (10-12 mm. long) projects, its 

 branches being at first apposed. Later on, when most of the pollen has been 

 removed, the three stylar branches diverge, and ultimately roll back until they touch 

 the style, coming into contact with any grains that may be left, so that automatic 

 self-pollination is possible. Nectar is secreted in the base of the flower round the 

 insertion of the style. 



Visitors. Delpino observed numerous Hymenoptera, and Loew (Berlin Botanic 

 Garden) saw a hover-fly (Syrphus balteatus Deg.) and Apis, skg. 



1738. P. limoniifolium Sibth. et Sm., and 1739. P. campannloides Bieb. 

 (Kirchner, op. cit.) These species resemble P. canescens in their inflorescences, 

 flowers, and no doubt their mechanism, but the blossoms of P. limoniifolium are 

 smaller. 



The following species belong to the sub-genus Hedranthum (flower class S). 



1739. P. Michelii All. (=P. betonicaefolium Vtll). Kirchner, Jahreshefte 

 Ver. Natk., Stuttgart, liii, 1897, p. 233. In this species there are about 100 flowers 

 in a head. Kirchner noticed (at Locarno) that at the end of anthesis the three stylar 

 branches roll back into circles, but do not usually reach the style, upon which indeed 

 no pollen as a rule remains. Automatic self-pollination can therefore only take place 

 very rarely, and insect-visits are so numerous that it is almost always unnecessary. 



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

 stated. 



Herm. Muller (Switzerland), a beetle, 8 flies, 17 bees, and 42 Lepidoptera 

 (' Alpenblumen,' p. 411). Loew (Switzerland), 2 bees (Bombus rajellus ^. , skg., 

 and Megachile analis Nyl. 5, po-cltg.) and an undetermined Noctuid ('Beitrage,' 

 p. 59). MacLeod (Pyrenees), 2 humble-bees, a hover-fly, and a Muscid (' Pyrenefe'nbl.,' 

 P- 371)- 



1740. P. spicatum L. In this species the head is made up of about 100 

 flowers, yellowish-white in colour with a green tip, and smelling faintly of vanilla. 

 Kerner says that automatic self-pollination ultimately becomes possible by rolling back 

 of the stylar branches. 



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

 stated. 



Knuth (on the Inselsberge in Thuringia, 16. 7. '94), 4 bees, skg. i. Apis mellifica 

 Z. 5 ; 2. Bombus agrorum F. <^; 3. B. lapidarius Z. 5 and S; 4. B. pratorum Z. J 

 (' BloemenbioL Bijdragen '). Herm. Muller (Teutoburger Wald), an Elaterid beetle 

 (Agriotes palliduus III. ?), a Nitidulid beetle (Meligethes aeneus F), a Staphylinid 

 beetle (Anthobium sorbi GylL, exceedingly numerous), and a bee (Apis mellifica Z. 5, 

 skg.) (' Weit. Beob.' Ill, p. 78). Alfken (Bremen), 2 humble-bees Bombus proteus 

 Gersi., and B. agrorum F. 



1741. P. nigrum F. W. Schmidt. (Kirchner, ' Flora v. Stuttgart/ p. 651.) The 

 heads of this species contain about 40 flowers of dark-blue colour. Kirchner says 

 the pollen is dark-red. 



