Penthorum sedoides

Care at a glance

Overview

Best understood as a paludarium and pond-margin plant that can also be grown submersed, not the other way round. Underwater it stays compact and grows slowly, so treat it as a midground accent, give it medium light and reasonable nutrients, and add CO2 if you want it to do more than hold position. The lance-shaped, serrated leaves keep their shape submersed, which gives it an unusual crisp texture among stem plants. Slow leaves collect algae under strong light, so do not blast it. In an open-top tank or riparium it will happily climb out of the water, and that emersed growth is where the plant really performs.

In the wild

Native to the eastern United States and Canada, where it grows on wet banks, in ditches and in marshy ground that floods seasonally. It is a hardy marginal rather than a true aquatic: plants stand emersed for most of the year and tolerate spells of shallow submersion when water levels rise. Emersed plants are winter hardy and colour up attractively in autumn.

Good to know

Penthorum sedoides is the American member of Penthoraceae, a tiny family with only one genus and two species, the other being Asian. The name sedoides means resembling Sedum, a nod to the stonecrop-like look of the leafy stems, though it is not a succulent and is unrelated to true stonecrops. Emersed plants reach 30-60 cm and carry distinctive five-parted seed capsules; submersed shoots stay smaller and more densely leafed.

Did you know

It carries a family all of its own: Penthoraceae holds just this species and one Asian relative, so a ditch stonecrop in a riparium is a whole plant family in one pot.

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