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Among the more interesting intergeneric artificial hybrids produced is that between Dubautia scabra and Wilkesia
hobdyi. Although both parents have 2n = 28 chromosomes their
genomes are differentiated by at least 2 reciprocal chromosome translocations, resulting
in 11 pairs and a chain of 6 chromosomes at meiosis and a pollen stainability of about
28%. (side by side comparison) |
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Another artificial hybrid involves Dubautia knudsenii and Wilkesia hobdyi. It has a pollen stainability of about 23 % and at
meiosis exhibits 11 pairs and 2 chains of 3 or a chain of 6 chromosomes.
(side by side comparison) |
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Great effort was taken to produce the artificial hybrid between Argyroxiphium
sandwicense subsp. macrocephalum and Wilkesia
gymnoxiphium. The species are found at opposite ends of the island chain and
having them flower synchronously in cultivation is an extremely unlikely event. In fact,
the flowering times of the species in the field are usually mutually exclusive. However,
during very favorable years there is a slight overlap in flowering and one such year
afforded the opportunity to produce a hybrid by collecting pollen from Wilkesia
on Kauai and flying it to Maui on the same day to pollinate stigmas of an early-flowering
individual of Argyroxiphium. This pollination "by jet aircraft"
resulted in several hybrid fruits. Though it was successfully cultivated for some time,
unfortunately this hybrid did not reach flowering maturity. (side
by side comparison) |
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Although the silversword/iliau hybrid died before flowering, the hybrid between Argyroxiphium grayanum (greensword) and Wilkesia
hobdyi (dwarf iliau) was more successful. Meiosis in this hybrid indicated that a
minimum of 2 reciprocal chromosome translocations distinguish the parental genomes. Pollen
stainability was about 20%. Note the very conspicuous glandular hairs with droplets of
"tar," a condition similar to many of the "tarweeds" of North America.
(side by side comparison) |
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The artificial intergeneric hybrid between Dubautia
plantaginea ssp. humilis and the silversword, Argyroxiphium
sandwicense ssp. macrocephalum bears a striking similarity to the
greensword, A. grayanum. Silverswords and Dubautia plantaginea
are sympatric on both E Maui and W Maui where greenswords occur, suggesting the
possibility of this sort of origin for A. grayanum. (side
by side comparison) |
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This remarkable hybrid combines the genomes of the Mauna Kea silversword (Argyroxiphium sandwicense ssp. sandwicense), the
greensword (A. grayanum), and Dubautia
linearis. It was produced artificially by first crossing the two Argyroxiphium
species. This hybrid had about 63% pollen stainability and exhibited 12 pairs and a ring
of 4 chromosomes during meiosis. This primary hybrid was then crossed with Dubautia
linearis to produce the trispecific hybrid which had about 12% stainable pollen and
exhibited 9 pairs, a chain of 6, and a chain of 3 chromosomes. (side
by side comparison) |
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This final example combines the genomes of 4 species of Dubautia. It was
produced by crossing two highly fertile primary hybrids that exhibited normal meiosis (Dubautia knudsenii x D. laxa
and D. microcephala x D.
plantaginea ssp. humilis). The secondary hybrid also had normal meiosis
and about 98 % pollen stainability. (side
by side comparison) |
