Pygmy Chain Sword

Anyone who has been in the hobby a while knows this plant as Echinodorus tenellus. Flowgrow files it under Helanthium tenellum and notes that the old name is still in use. It is the smallest of the runner-forming sword plants and a variable one. The form usually in trade has very narrow submersed leaves, about 1.5 mm wide and 6 to 10 cm long, sometimes longer, in medium to olive green or even reddish. A second form from North America, sold as parvulum, has lighter leaves around 2 mm wide, and is rarely cultivated now.

Where it comes from is less settled than the care sheet. Flowgrow says the trade variety originates from the American tropics and puts a question mark after Brazil, so this entry keeps the question mark instead of resolving it.

Runners are the whole story with a carpet plant, and this one sends them out quickly. Flowgrow rates growth fast, gives propagation as runners, and describes the result as a grass-like lawn. It also rates the plant medium difficulty, a step up from the easy this entry used to claim with no source behind it. The published optimum is 18 to 28 °C with pH 5 to 7.5, carbonate hardness 0 to 14 dKH and medium to high light. The tolerance band is unusually wide, 10 at the bottom and 35 at the top.

Two gaps worth naming. The page has no height row, so the 10 cm here comes from the leaf length in its description rather than a published figure. And it says nothing about CO2 beyond a 20 to 40 mg/l range, so the injection label on this entry is inherited from the old stub rather than taken from the source.