H. Yoshino, T. Ochiai and M. Tahara (2000) Phylogenetic relationship
between Colocasia and Alocasia based on molecular
techniques. In: D. Zhu, P. B. Ezyaguirre, M. Zhou, L. Sears and G. Liu
(eds) Ethnobotany and genetic diversity of Asian taro: focus on
China. International Plant Genetic Resources Institute and Chinese
Society for Horticultural Science, Beijing. pp. 66-73.
A taro strain collected in Nepal in 1973 was considered to be an
intergeneric hybrid between Alocasia and Colocasia, on the
basis of chloroplast DNA analyses carried out in the 1980s (but see later
work with isozymes, noted below).
Subsequently, an artificial cross was attempted and numerous seeds
were obtained after a cross between C. esculenta var.
aquatilis (Hassk.) Kitamura (from Nepal) and Alocasia brisbanensis (F.
M. Bailey) Domin (ex Kyoto Botanical Garden). Most seeds did not germinate
and only a single plant developed fully.
This plant was triploid and chromosome painting using genomic in
situ hybridisation (GISH) showed that 14 of 42 chromosomes were
derived from A. brisbanensis.
It was concluded that the plant was an intergeneric hybrid, formed as
an unreduced egg of C. esculenta fertilised with normal A.
Isozyme analyses by V. X. Nguyen (1998), PhD, Okayama University,
contradicted the original interpretation of the Nepalese hybrid,
indicating that it was a cross between C. esculenta and C.
gigantea (i.e. intra-generic, not inter-generic).
Comments by PJM:
Among other Asian accessions (Nepal and China) Nguyen found further
examples of hybridsation between C. esculenta and C.
gigantea. Taxonomically, C. gigantea is possibly misplaced
in Colocasia, but it is not necessarily to be regarded as closer
to Alocasia. As Yoshino points out, and as Tony Avent indicates in
this list, there is much to be learned about hyribidisation among these
The experimental survival of a hybrid between genera was made
possible by a rare polyploidisation event that allowed odd chromosomes to
be carried along by a normal full complement of chromosomes.
Vigorous offspring are less likely after intergeneric crosses than
after interspecies (intrageneric) crosses. An intergeneric crossing has
not yet been proven to occur in the wild, though it is possible in
Dear Pete and Marek:
x Colocasia hybrid that you mentioned looks a lot like A.
macrorhizos. I was fortunate to examine this hybrid several years
ago growing at a Hawaii taro research station. It was found in an
area of Nepal where the two genera grow together. On our
expedition last year to N. Vietnam, we visited a restricted military
area near the China border. We found Colocasia gigantea growing
with Alocasia macrorhizos. Growing among them were several plants
that superficially appeared to be bi-generic hybrids. We have not
had these plants tested yet to confirm this yet, so this is just a
preliminary observation. If anyone is doing work in that region, I
will be glad to direct them to the population for further
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