NOTES ON MISTLETOE 



^9^ 



paper by the late Dr. Bull of Hereford on Viscum album (Trans. 

 Woolhope Club, 1852-1865, p. 312) he states that out of 36 seeds 

 taken at random, 25 had a pair of radicles. I put 30 seeds, also 

 taken haphazard, in a patch on the trunk of a plane-tree. Three 

 o-f these were lost, and of the remaining 27, two radicles came 

 from 19, which is almost exactly the same proportion as in Dr. 

 Bull's experiment. But where he obtained only 1 seeds with 

 single rftdicles out of 36, I grew 7 out of 27 — a very much larger 

 proportion. Also in the older experiment 7 seeds had 3 radicles, 

 whereas I had only 1. I am removing all the seeds except the 

 7 singles, which I hope to grow in order to see whether this fact 

 has any influence on sex. 



II. Fertilization. 



The manner in which fertilization is effected is somewhat 

 difficult to follow. Those w4io have written on the subject do 

 not seem to record the dates at which their observations were 

 made, and much depends on this. In the Herefordshire orchard, 

 above mentioned, the Viscum was in flower this year (1916) from 

 the last few days of January, throughout February and March, 

 and was over by the beginning of April. The oldest plants flower 

 earliest and the youngest latest. At one time mistletoe was 

 classified as anemophilous. Knuth {Handbook of Floiver Pollifia- 

 tion, translated by J. Ainsworth Davies, Clarendon Press, 1909, iii, 

 p. 360) says : " Kolreuter declared positively in 1762 that mistletoe 

 is entomophilous, but the plant was considered anemophilous for 

 a long time, until Loew's investigations proved entomophily 

 beyond doubt." He then quotes Kolrenter's and Loew's observa- 

 tions at length, but neither author specifies the insect visitants : 

 the former states the pollination " is efl'ected entirely by insects 

 and indeed chiefly by various genera of flies " : the latter '* was 

 unable to observe pollinators, but supposed these to be short- 

 tongued bees . . . [he] thinks early flying species of Andrena 

 are pollinators . . . some of which appear as early as the middle 

 of March, the flowering time of the mistletoe." Kirchner (Jahres- 

 heft. Ver. Natk. Stuttgart, xlix, 1893, p. 101) says : " Both male 

 and female flowers clearly secrete nectar, the male ones usually 

 less than the female, the latter being sometimes full up to the 

 tips of the perianth lobes. These in the male flower at the 

 beginning of anthesis are so upright that the brittle pollen burst- 

 ing from its receptacles bars the way to the base of the blossom, 

 and must therefore adhere to the proboscis of an insect probing 

 for nectar. . . ." " Visitoes. — The following were recorded by 

 the observers stated : Kirchner, the honey-bee, only visiting the 

 male stocks, and leaving alone the smaller feebly odorous female 

 flowers, which of course yield no pollen. Pollination is effected 

 by flies : Polle7iia rudis (freq.), P. vesinllo (do.), Sjnlogaster dupli- 

 ca^a (less freq.), which visit flowers of both kinds. Bonnier saw 

 the honey-bee" (Knuth, p. 362). 



One must note that neither Kolreuter nor Loew name any 

 insects in particular as pollinators, the former contenting himself 



