There is much ado about which plants are reeds or rushes; the word 'rush' comes from a very old word related to weaving or knitting, and therefore to an ethnobotanical, economic use for such plants, rather than a botanical label in the stricter, modern sense. The related term, 'reed', is a West Germanic word of uncertain source: it is unknown in both North Germanic and Gothic. The word 'cane' comes to us from Latin as it derives from 'canna', and can ultimately be traced to a Mesopotamian source referring to reeds, canes, pipes, arrows, and measurement. The word is cognate with 'channel' and 'canal', indicating an ancient, watery association.
In botany the word 'rush' came to be associated with the genus Juncus, henceforth the 'true rushes'. Yet whilst tall rushes and their kin are among the plants that clothe wild watersides - and that water gardeners cultivate as marginals - there are also short species of rush. One of these is quite widely cultivated in our aquariums: it is the lesser creeping or soft rush, Juncus repens. This species is best associated with the southeastern USA, with records from such locations as Mexico and Cuba. In the wild, J. repens is a habitat generalist, which adapts to streams, ponds and lakes, and manmade ditches.
Wild J. repens possess two growth forms, one terrestrial which can reach 1 and a 1/2 meters, or 60 inches; and the other is, of course, the submerged form of interest to aquarists. This form even flowers underwater, so there is no question that J. repens can grow as a true aquatic plant - a fact confirmed by many aquarists. Although it's rhizome is quite short, it spreads using modified, prostate shoots, and can thus spread quite well. In the wild it is considered an effective competitor. Ecologically, J. repens shows some preference for a wet, acidic environment with slightly enriched nutrient conditions. It is less common where the pH exceeds 7 but can tolerate as low as 3.5. Beyond this, the rush has a broad ecological range.
In the aquarium, J. repens has earned a reputation as an undemanding, hardy, and versatile grass-like plant, that is commonly used in the mid- and backgrounds of aquascapes. This rush has 'medium' light demands, but tolerates brighter light. It does not really need CO2 dosing specially. In the aquarium it commonly grows to 10 centimeters or 4 inches tall, though 30 centimeters or 12 inches is certainly possible. This fine plant tolerates the temperatures of ordinary, tropical aquariums, because the summer temperatures within it's native range may be so high.
