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They are probably all components of the one floristic element, a tropical one with a 
primary centre in southeast Asia, which has diversified in the Malesian region, and 
which is represented further southeastwards in Australia only as an attenuated 
intrusive stock. 
Endemism, dispersibility, and effectiveness of sea barriers 
Effective seed dispersal in most mistletoes is by fruit-eating birds, and demonstrates 
close mutualism involving fruit and embryo structure, germination, and bird anatomy 
and behaviour (Doctors van Leeuwen 1954; Reid 1989, 1995; Barlow and Schodde 
1993). The ovoid "seed", 5-12 mm long, is covered by a viscous layer rich in 
carbohydrates. The seed is removed from the fruit and swallowed whole, and passes 
through the short alimentary canal of the bird rapidly, commonly in 10-20 minutes. 
Although nutrients have been absorbed from the viscous layer, it is intact when the 
seed is voided, usually on to a slender tree branch. The viscous layer cements the 
seed in place, and it germinates spontaneously once removed from the fruit wall. 
Because of the nature of the seed dispersal mechanism, dispersibility in mistletoes is 
normally very low (Barlow and Schodde 1993). The families have strongly continental 
distributions, with occurrences on remote islands being exceptional (see below). 
Present distributions have probably been established primarily through migration 
over continuous land surfaces, and this allows high confidence in the correlation of 
phytogeny and migration. 
Genetic differentiation in mistletoes is therefore likely to be relatively local, and 
endemism at species level is accordingly relatively high. Earlier students of the 
families, such as Blakely and Danser, generally assumed that species distributions 
did not cross significant water barriers, although Danser did accept a number of 
very widespread Malesian species, some reaching Australia. 
Views of successive authors on levels of endemism in Australian mistletoes are 
summarized in Table 3. Blakely considered all Australian mistletoes except one 
species of Viscum to be endemic. Danser accepted only three widespread Malesian 
loranths as present in northern Australia, but in Viscaceae considered half the 
species to be non-endemic. Barlow has recorded higher numbers of non-endemic 
species in both families. 
Table 3. Levels of endemism in Loranthaceae and Viscaceae, as recognized by successive 
students of the family. 
Species 
Loranth 
Vise 
Blakely 
(1922-1928) 
45 
10 
Danser 
(1929-1941) 
47 
10 
Barlow 
(1966-1993) 
74 
14 
Non-endemic Percent 
species endemism 
Loranth 
Vise 
Loranth 
Vise 
0 
1 
100 
90 
3 
5 
94 
50 
17 
7 
77 
50 
