Japanese Thistle

Perennial herbs, stems 0.5−1.8 m tall, without rosette leaves. Leaves pinnatipartite or pinnatisect, 27.5−30.6 cm long and 17.8−20.2 cm wide, U-shaped space between pinnae, smooth, elliptic to broadly elliptic, base truncate to cuneate, apex caudate, pinnae 8.3−10.4 cm long and 17.2−18.6 mm wide, space between pinnae 2.5−3.0 cm, 6−7 pairs. Capitula arranged into racemes or panicles, mature capitula nodding, involucre bowl shaped, 3.4−3.8 cm long and 1.5−2.0 cm wide. Involucre lacking abaxial appendages, inner phyllaries acute apically, outer phyllaries green with indistinct layers, 1.6−1.8 cm long and 1.8−2.4 mm wide, protrusion 6.0−11.0 mm. Florets with white corolla, 2.8−3.1 cm long, corolla lobes 5.2−6.0 mm long and 0.4−0.7 mm wide; 5 synantherous stamens, detached filaments with irregular protuberances, basal caudate extensions, white or brown, anthers 5.4−8.2 mm long, filaments 6.8−8.0 mm long. Stigmas bifid apically, style 2.0−3.4 cm long, ovaries 1.5−2.0 mm long. Achenes oblong, base acute, apex truncate, beige, 4.3−4.9 mm long and 1.7−1.8 mm wide, long tube-shaped beak apically. Pappus 1.3−2.1 cm long forming basal ring, easily shed.

Endemic to central-northern Taiwan. Preference for gullies and valleys at 1500−3500 m alt. (Fig. 3).