Three New Species of Hydrobryum (Podostemaceae) from Laos

Two new species of Podostemaceae are described from a single site in northern Central Laos. Hydrobryum hapteron is characterised by the many long holdfasts in the basal area of the crustose root and the long stalks of capsules. It shares the prominent holdfasts and stalks of capsules with H. ramosum (C. Cusset) Koi & M. Kato but is distinct from it in the crustose root. Hydrobryum subcylindricoides is similar to H. subcylindricum Koi & M. Kato in the ribbon-like root but differs from it in the wider root, Y-shaped stigmas and fewer ribs on the capsule.