TankBud

Persicaria praetermissa

Also known as Polygonum sp. 'Ruby', Polygonum praetermissum, Persicaria sp. Ruby

FreshwaterStemCuttings

Persicaria praetermissa (Persicaria praetermissa)
Show_ryu · CC BY-SA 3.0

Care at a glance

Light
Medium light
CO2
CO₂ beneficial
Temperature
64–86°F
18–30°C
Max height
13.8 in
35 cm
Growth rate
Fast
Placement
Midground
Type
Stem
pH
5.0–7.0
Hardness
0–14 dGH
Spread
5.9 in (15 cm)
Nutrient uptake
Root + water column
Growth region
Submersed or emersed
Difficulty
Medium
Family
Polygonaceae
Origin
Tropical Asia and Australia

Overview

Persicaria praetermissa is a fast-growing stem plant that fills the midground and drapes over hardscape in a way vertical stems cannot. It is of medium difficulty, though not hard by Persicaria standards.

Did you know

The species name praetermissa means overlooked. It fits a plant that spent years in the hobby under the wrong name, Polygonum sp. 'Ruby', before anyone worked out what it actually was.

Caring for Persicaria praetermissa

Plant cuttings in open substrate and give the group room to spread sideways rather than height. Persicaria praetermissa feeds through its roots and its leaves, so root tabs and a liquid fertilizer both help.

It wants medium light and grows without injected CO2. Underwater it turns brown-red to brown-orange, strongest under good light with CO2 and steady nutrients. On less it survives, but it loses color and density, and it sulks in lean, dim tanks. It handles 64 to 86°F (18 to 30°C).

It grows fast. Let the sparsely branched shoots run, then trim back to a node and replant the tops when it wanders too far.

Good to know

Persicaria praetermissa is a knotweed in the family Polygonaceae, identified only after it entered the hobby. It carries narrow, spear-shaped alternate leaves up to about 7.5 cm long on short petioles. Unlike most stem plants, its shoots grow squarrose, leaning diagonally to almost horizontally instead of heading straight for the surface.

In the wild

Persicaria praetermissa is native to large areas of tropical Asia and Australia. It grows in marshes, in wet ditches and on the muddy margins of still water. Like its relatives it is amphibious, standing emersed on wet ground and growing fully submersed when flooded. Aquarium stock converts readily between the two forms.

Common questions

Does Persicaria praetermissa need to be planted in the substrate?

Yes. Strip the leaves from the lower part of each stem, then push the stems into the substrate one at a time, a little apart.

Does Persicaria praetermissa need CO2?

No, but it helps. Persicaria praetermissa can grow without injected CO2, and added CO2 makes it grow faster.

How much light does Persicaria praetermissa need?

Persicaria praetermissa wants medium light. A light sold for planted tanks covers it.

Does Persicaria praetermissa need root tabs?

They help. Persicaria praetermissa takes nutrients through both its roots and its leaves. Root tabs near its roots and a liquid fertilizer cover both.

How do you propagate Persicaria praetermissa?

Persicaria praetermissa propagates by cuttings. Cut off the top of a stem and replant it, and the stump left behind grows new shoots.

How tall does Persicaria praetermissa grow?

Persicaria praetermissa grows to about 13.8 in (35 cm) tall. It grows fast, so expect to trim it often.

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