part ur] © THE MECHANISMS OF FLOWERS. 489 
proboscis to reach the honey; adhesive matter secreted by the 
outer surface of the perfect anther-lobe (which is turned towards 
the centre of the ring) is thus applied to the proboscis and pollen 
is then cemented to it. In the flower next visited, the hollow 
cup-shaped stigma scrapes off the adherent pollen from the 
proboscis (178, 360). 
Marrubium, L., like Sideritis, has adhesive glands upon its 
anthers. An account of the structure of its flower and a list of 
its visitors are given in my Weitere Beobachtungen, U1. pp. 50, 51. 
Physostegia, Benth., according to Delpino, is proterandrous, and 
the stigma comes to occupy the place of the anthers. In P. virgini- 
ana, teeth at the edges of the valves of the outer pair of anthers 
aid the complete removal of the pollen by insects (178, 360). 
355. PRUNELLA VULGARIS, L.—This species, like so many other 
Labiates, includes two forms, one with large hermaphrodite, the 
ho 
Fic, 165.—Prunella vulgaris, L. 
1.—Hermaphrodite flower, from the front. 
2.—Upper part of a long stamen. 
3.—Upper part of a short ditto. 
other with smaller female flowers in which only rudimentary 
functionless remains of the stamens persist. In Prunella vulgaris 
the female form is much rarer than the hermaphrodite. 
In the small-flowered form the tube is only 4 to 5 mm. long; 
the style projects beyond and above the upper lip, and its two 
stigmas diverge widely. I have found not only the stigmatic 
papille, but the whole inner surface of the entrance of the flower 
in this form, thickly covered with pollen, proving that insect-visits 
were plentiful in both forms of the flower. 
