PAMMEL POLLINATION OF PHLOMIS TUBEROSA. 245 



Loew (61 d) found Fh. Russeliana visited in the Berlin Botanic 

 Garden only by Bombus hortonim, and he says that Anthophora 

 pilipes is the only other insect in North Germany which can do 

 adequate service in its pollination. 



In both of these species there is a beautiful contrivance for secur- 

 ing cross-pollination. But while the Syrian, according to Loew, 

 is proof against such depredators as Bombus ierrestris, which per- 

 forates many European flowers in order to get at their nectar, Ph. 

 tuberosa is not proof against these unwelcomed visitors. Notwith- 

 standing that Xylocopa has a tongue of 7.5 mm. and can there- 

 fore get at a portion of the nectar in a normal way, it chooses 

 rather to perforate the flowers, the awn-pointed calyx lobes ofler- 

 ing no resistance. 



But I think the most striking difference between the species is 

 in color, and as this is such an interesting biological fact I will 

 summarize what Hermann Miiller says about it in his classical 

 work "Die Befruchtung der Alpenblumen" (90a) : 



Not only have Hjmenoptera been most active in the development of 

 such peculiar contrivances as the bell-shaped corollas of Convallarias, 

 Campanulas, and Gentians; the funnel shaped corollas of Rhododen- 

 drons and Echiums ; the tubular corollas of Loniceras ; the closed corollas 

 of Linarias and Antirrhinums ; the spurred flowers of Aquilegias and 

 Aconitums; the labiate flowers of Lamiums, Salvias, Melampyrum, and 

 Pedicularis ; the inverted flowers with small openings of Arctostaphy- 

 los and Vaccinium ; and the papilionaceous flowers of Trifolium and 

 Robinia; — but they have also influenced the colors of flowers in a most 

 marked degree. Flowers adapted to a large range of insects, like those of 

 Compositce, Saxifragecv, ValerianaceiB, Poteniilla, and Ranunculus, are 

 usually yellow or white. But in such highly modified flowers as Lami- 

 ums, Salvias, Delphiniums, Aconitums, and Aquilegias, the colors are 

 generally violet, blue, pink, or purple. In these and other genera a change 

 seems to have stepped in, especially where flowsrs have the same structure 

 and are pollinated by the same class of insects. 



Our species of Monarda show this color-range beautifully. M. 

 didyvia* is bright red, M. fisiulosa is rose color varying to white, 

 M. Bradburiana is pale purplish-white, M. punctata is yellowish. 

 Dicentra Cafiade?isis is white, D. eximia purple. Viola striata is 

 white, V. pubesce7is yellow, V. pabnata vd^x. cucullata blue. Of Eu- 

 ropean examples, Aconitum lycoctonum is yellow, A. Napellus blue ; 



* This species is adapted to Lepidoptera for pollination. 



