Spiraea trichocarpa Nakai

Family : Rosaceae

Spiranthes sinensis (Pers.) Ames (Synonym : Spiranthes sinensis (Pers.) Ames var. amoena (M.Bieb.) H.Hara)

Family : Orchidaceae

Spirodela polyrhiza (L.) Schleid. (Synonym : Lenticula polyrhiza (L.) Lam.)

Family : Lemnaceae

Spodiopogon cotulifer (Thunb.) Hack. (Synonym : Andropogon cotulifer Thunb.)

Family : Poaceae

Spodiopogon sibiricus Trin. (Synonym : Andropogon sibiricus (Trin.) Steud.)

Family : Poaceae

Sporobolus fertilis (Steud.) Clayton (Synonym : Agrostis fertilis Steud.)

Family : Poaceae

Sporobolus pilifer (Trin.) Kunth (Synonym : Sporobolus ciliatus J.Presl var. japonicus (Steud.) Hack.)

Family : Poaceae

Stachys agraria Schltdl. & Cham. (Synonym : Stachys polysegia Briq.)

Family : Lamiaceae [Naturalized plant]

Stachys oblongifolia Benth. (Synonym : Stachys palustris L. var. imaii Nakai)

Family : Lamiaceae

Stachys riederi Cham. var. hispidula (Regel) H.Hara (Synonym : Stachys palustris L. var. hispidula Regel)

Family : Lamiaceae