Usually less than 25 cm tall with fewer than 20 heads per inflorescence axis. Taproot light brown. Radical leaves lyrate-pinnatifid, velvety. Inflorescence axes densely puberulous at least at base. Achene reddish brown to dark purplish brown, 2–2.5 mm long.
Endemic to littoral, raised coral reefs in Hsiao Liuchiu (小琉球) and southwestern Shoushan. Rare subspecies. Adapted to littoral habitat. Dispersal by wind. The "2017 Red Data List of Vascular Plants in Taiwan" rated its threat level as "Least Concern, LC" (Least Concern, LC).
The discovery of Youngia japonica (L.) DC. subsp. formosana (Hayata) Kitam. 台灣黃鵪菜 could date back to 1911, when 早田文藏 name the plant that 川上瀧彌 and 中原源治 collected at Takao(打狗) in 1906 as Crepis formosana Hayata. The species was then move into genus Youngia and treated as a subspecies of Y. japonica (L.) DC. In 1998, Flora of Taiwan 2nd edition was published, treating the plant as endemic subspecies Y. japonica subsp. formosana (Hayata) Kitam in Taiwan, while widely distributed in Taiwan island with an altitude of 1500 to 2500 meters, different from the original described locality. The confusion was cleared after professor Chung, K. F. (陳玉峰教授) noticed its existence at littoral, raised coral reefs during his explore in southwestern Shoushan. He and his team then started the researches on Y. japonica in Taiwan, ending the misapplication of Y. japonica subsp. formosana (Hayata) Kitam.
Reference:
Nakamura, K., Kono, Y., Huang Jr, C., Chung, K. F., & Peng, C. I. (2013). Correction of confusions regarding the identity and synonymy of Youngia (Asteraceae: Tribe Cichorieae) in Taiwan. Systematic Botany, 38(2), 507-516.
Nakamura, K., Chung, K. F., Huang, C. J., Kono, Y., Kokubugata, G., & Peng, C. I. (2012). Extreme habitats that emerged in the Pleistocene triggered divergence of weedy Youngia (Asteraceae) in Taiwan. Molecular Phylogenetics and Evolution, 63(2), 486-499.
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