kingdom Plantae - plants »  divisio Magnoliophyta - flowering plants »  class Rosopsida - eudicots » order Malpighiales »  family Violaceae »  tribus Violeae > genus Viola > Viola sect. Plagiostigma Godr.  > Viola subsect. Adnatae W. Becker 

Viola woosanensis Y. N. Lee & J. Kim

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Synon.:

Common name: 우산제비꽃

Description:  Hybrid between V. ulleungdoensis and V. chaerophylloides . Viola woosanensis is a herbaceous perennial, sporadically occurring around and near Seonginbong [the highest peak of Ulleung Island (984 m)], and shows somewhat intermediate morphological characteristics between the two putative parents, V. ulleungdoensis and V. chaerophylloides. In general, V. woosanensis has irregularly dissected and serrate heart shaped leaves with violet flowers. By comparison, V. ulleungdoensis has heart shaped and serrate leaves and violet flowers and V. chaerophylloides has highly dissected compound leaves and white fragrant flowers

Distribution:  Native Asia-Temperate EASTERN ASIA: Korea [Is. Ulleung ]

Habitat: V. woosanensis is sympatric with the two species in Ulleung Island. Viola ulleungdoensis, another endemic violet in Ulleung Island, is restricted to relatively high elevations (between 567 and 896 m) around the highest peak, Seonginbong (984 m). On the contrary, V. chaerophylloides is widely distributed in eastern Asia, and typically occurs at lower elevations (between 350 and 554 m) in Ulleung Island. Viola woosanensis occurs in altitudinal ranges where the two parental species overlap, and at a higher elevation (between 554 and 890 m above the sea level). Furthermore, two putative parent species have somewhat narrow flowering period on island, i.e., from mid to late April, but their flowering periods are overlapped, providing a window of opportunity for interspecific hybridization

Notes: Although two parental species are primarily sexually reproduced and either non-rhizomatous (V. chaerophylloides) or with weakly-developed rhizome (V. ulleungdoensis), the reproductive status of V. woosanensis is highly sterile and appears to be reproduced exclusively via well-developed rhizomes (i.e., asexual reproduction). Since the taxon is not spatially and ecologically isolated from its parental species, the evolutionary fate of this hybrid is yet to be determined. 

References:

1. Hee-Young Gil,  Seung-Chul Kim.Viola woosanensis, a recurrent spontaneous hybrid between V. ulleungdoensis and V. chaerophylloides (Violaceae) endemic to Ulleung Island, Korea Journal of Plant Research volume 129, pages807–822(2016) DOI 10.1007/s10265-016-0830-3