|D. ciliolata||Natural Hybrid||D. scabra|
Dubautia scabra is sympatric and hybridizes with several 13-paired species, including D. ciliolata, D. linearis, D. menziesii (Fig. 1), D. platyphylla, D. reticulata, and D. waianapanapaensis. These hybrids can be readily recognized by their intermediate nature, including pale lemon-yellow flowers and a chromosome number of 2n = 27. The maximum meiotic chromosome pairing configuration is always the same, consisting of 12 pairs and 1 chain of three chromosomes. Pollen stainability in these hybrids often ranges from 70-90%. Dubautia ciliolata and D. scabra hybridize at countless sites of sympatry on the island of Hawaii. In hybrid photo 1, both parents and the hybrid are seen to be closely spaced on a cinder field at Devastation Trail, Kilauea, HI. Photo 2 depicts a very large hybrid clump with D. scabra in the foreground (Devastation Trail, Kilauea). Photo 3 shows a flowering branch of a hybrid (Devastation Trail). Photo 4 is a flowering shoot of a hybrid from Hualalai, HI. In the saddle area between Mauna Kea and Mauna Loa is a particularly interesting site where D. ciliolata is restricted to kipuka (islands) of a prehistoric, mostly a'a lava flow and D. scabra is restricted to the surrounding 1935 flow of mostly pahoehoe lava (see Photo 5). Hybrids occur primarily on the the perimeter of the recent lava flow, usually at interfaces with the older substrate. A study of flavonoid compounds in hybrids suggests that recombination beyond the F1 generation is occurring at this site. This hybrid combination has also been produced artificially (Photo 6) and several cultivated individuals have reach flowering maturity. The formal designations Railliardia laxiflora DC., R. ciliolata var. laxiflora Sherff, and R. fauriei have been applied to this hybrid combination.
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