Helanthium tenellum, the pygmy chain sword, is still also known under its synonym Echinodorus tenellus. It is the smallest known species among the runner-forming sword plants, and rather variable. The variety usually found in trade originates from the American tropics (Brazil?). Its submersed leaves are very narrow, pointed, and of a medium to olive green or even reddish. They grow to a length of 6 to 10 cm, sometimes even longer, and a width of about 1.5 mm. Their widest part lies above the middle, around 2 cm below the tip.
The submersed leaves of another form originating from North America (see Helanthium tenellum "parvulum"), though rarely cultivated today, has always light green leaves that are not as narrow, with around 2 mm width. They have their widest part below the middle.
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