Drosera x sidjamesii (Droseraceae): systematics and ecology of a natural hybrid from Western Australia

摘要

The natural hybrid Drosera x sidjamesii Lowrie & Conran from Lake Gnangarra north of Perth, Western Australia is described and defined as a cross between D. nitidula Planch, subsp. omissa Marchant & Lowrie auct. non Diels and D. pulchella Lehm., between which it shows a high degree of intermediacy for almost all characters. Cytological examination of the hybrid and its parents confirms that the former at 2n = 46 is a combination of the In = 28 in D. nitidula subsp. omissa and 2n = 18 in D. pulchella.The hybrid grows along a narrow ecotone between the parental species, largely on sandy peat and along a presumed soil moisture/elevation gradient caused by the nearby lake. Nevertheless, within this ecotone the hybrid is significantly more frequent thaneither parental species, with D. pulchella mainly growing in peat soils closer to the lake and D. nitidula subsp. omissa on white sand further from the water. Field observations of morphotypes also suggest that the hybrid has arisen several times at the site, and that a limited number of plants at the site are becoming fertile and setting seed.