疏序唐松草 shu xu tang song cao

Plants ca. 70 cm tall, glabrous. Stems branched. Leaf blade 2-ternate; petiolule 20--40 mm; leaflet blade ovate or narrowly so, 5--8 × 3--5 cm, papery, base rounded, subtruncate, or shallowly cordate, margin unevenly 2--6-toothed on each side, apex subacute; veins raised abaxially; lateral leaflets smaller, shortly petiolulate. Inflorescence terminal or axillary, paniculate, ca. 7.5 cm. Bracts linear, 2--5 mm. Sepals early deciduous. Stamens many; filament filiform, 2--3 mm; anther linear, ca. 1 mm. Carpels 6--8; style circinate, ca. 1 mm. Achenes cylindric-ovoid, ca. 2 mm. Fl. Mar.

* W Hubei.

This species is similar to both Thalictrum faberi and T. grandidentatum, but differs from the former species in having leaflets obtusely toothed apically, inflorescence pubescent, and filaments slender, and from the latter species in having leaflets slightly cordate at the base, inflorescence pubescent, filaments slender, and achenes few. Thalictrum laxum is also similar to T. robustum, which differs in having stems and leaves glabrous and leaflets acutely toothed apically.