BY W. F. BLAKELY. 



Mimicry or Imitative Powers of Loranthus. 



I cannot say that I am greatly impressed with Loranthus as having any 

 marked power of mimicry. To my mind, based upon field observations, the 

 iP'eat controlling factor in the variability of a species is ecological. The 

 Loranth is what environment makes it, not a desire of the plant to conceal 

 its identity by imitative means, but one solely to derive as much nutriment as 

 it can from its host. 



I have arrived at this conclusion after a careful examination and study 

 ci various species, extending over four years, noting the condition of the host, 

 favourable or unfavourable, attachment of the parasite in relation to the host, 

 and the climatic conditions prevailing. Shade and exposure have a great in- 

 fluence on the development of the size, shape, colour, thickness or texture of 

 the leaves, and also on the colour of the flowers. Likewise a sound attachment 

 aud a vigorous food plant play a most important part in the life of the parasite. 

 There is, however, a gradual development of different forms of some species 

 which, though difficult to describe, manifest themselves irrespective of host dif- 

 ferentiation, and which may be termed species in the making, or in the evolu- 

 tionary stage, without easily defmable chai-aeters. 



One of the commonest species in the Port Jackson district is Phrygilanthus 

 eucalyptifolius, which is beyond doubt the most polyphagus of our mistletoes; 

 notwithstanding its large assortment of food plants, it does not show any par- 

 ticular or marked signs of mimicry of any of them. Its leaves show the same 

 uniformity when growing on Acacia Baileyana as on A. mela7WxyloH, A. implexa, 

 or when parasite on Angophora cordifolia, and on the long jointed terete branch- 

 lets of Casuarina. In fact I have seen specimens from the latter with leaves 

 remarkably broad and long, which might be said to be ridiculously out of all 

 proportion to those of the host, and are contrary to all attempts at mimicry. 

 This also applies equally to P. celastroides, Loranthus congener, L. pendulus, L. 

 Miquelii, L. vitellinus and others that I have noted in the field. 



W. P. Hemsley (Jour. Linn. Soc, xxxi., 308) draws attention to the re- 

 markable similarity of the leaves of L. pendulus to those of Eucalyptus amy- 

 gdalina (radiata). The close analogy of the lea.ves of some of our Loranths 

 and Eucalypts and other hosts is readily admissible. But is it not attributable 

 to homoplasy, rather than to sensitiveness or instinct on the part of the plant 

 to conceal its identity? On this subject Spencer Moore writes (Jour. Linn. Soc, 

 xxxiv., 1898-1900, p. 259) "The frequent close resemblance between certain 

 species of Loranthus and their hosts was noticed by me. Nor was it without 

 interest that I leamt, on my return home, how the same fact had been alluded 

 to by that sagacious obseirver, James Di-ummond. [Seei below]. The two species 

 showing this resemblance best are Loranthus pendulus, Sieb., var. parviflora, 

 which is difficult to descry when growing upon the Quandong, and L. Quandang, 

 Ldl., of which the leaves are strikingly similar to those of its host, an Acacia. 

 But it may be doubted whether mere homoplasy is in point here, seeing that 

 the parasites are greedily eaten by camels, f and so are, in all probability, 

 eijually attractive to vegetivorous marsupials. In these cases, therefore, the re- 

 semblance may possibly be protective, and may have been perfected by means 

 of natural selection. The attraction probably lies in the flowers, which contain 

 much nectar and are very sweet in consequence." f "Camels will browse upon 

 the parasites and leave the hosts quite untouched, although the latter are them- 

 selves excellent food. There would be stronger support for the suggested inimi- 



