Chromosome Homology in Dendrobium— K amemoto, Shindo, and Kosaki 
115 
species, but a few heteromorphic pairs were 
observed in some of the hybrids, which sug- 
gested morphological changes in certain ho- 
mologous chromosomes of the parental species 
involved. 
Including the natural hybrid, D. superbiens, 
the between-section diploid hybrids of Phalae- 
nanthe and Ceratobium exhibited irregularities 
in meiosis with the number of bivalents in each 
hybrid averaging from 15.7 to 18.9. 
A within-Ceratobium tetraploid hybrid, D. 
stratiotes x D. undulatum formed 1 or 2 quad- 
rivalents and behaved somewhat like an auto- 
tetraploid, while a tetraploid hybrid between 
Ceratobium and Phalaenanthe, D. phalaenopsis 
x D. gouldii formed only bivalents, similar to 
an amphidiploid. 
A Ceratobium-Latourea hybrid formed an 
average of 10.8 bivalents per PMC, while a 
Phalaenanthe-Latourea hybrid formed only 1.8 
bivalents. It can be concluded that Ceratobium 
and Phalaenanthe are relatively closely related, 
while Latourea is more distantly related to Cera- 
tobium and Phalaenanthe, and that if sequential 
divergence occurred in these groups, the order 
appears to be Latourea to Ceratobium to Phalae- 
nanthe. 
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