ruderal species

From the Latin Rudus, Ruderis means discharge, or waste. Ruderal plants appear in open, disturbed, unstable environments, rubble, and wastelands. They are also called pioneer species, as they are the first vegetation to appear after a disruption or modification of local ecological assemblages. Their presence brings life back to wasted places and transforms the terrain. Over time, ruderal plants disappear to gradually give way to perennial plants. Though hardy, ruderal plants do not necessarily have an easy life. Their habitats are sometimes ephemeral, dispersed, and limited, and competition with perennial plants may push out ruderal species. When forced to give way to more long-term inhabitants, ruderal species have two choices: migrate or wait. They may migrate through various seed dispersal techniques (such as the white puffs of dandelions gone to seed); or they may wait it out, decades or longer if need be, until a new environmental shake-up comes along and their long-buried seeds are given a chance to sprout again. (Coulon 2014) The Geneva Botanical Gardens houses a space dedicated to pioneer plants, dubbed the “zone rudérale.” The ruderal zone’s environment was carefully created with the use of certain materials (sand, gravel, cobblestones) as well as the use of certain visual signs of human presence (train tracks, a small wagon, a car bumper). Of course, Geneva’s ruderal species may be easily spotted as well outside of the protected confines of the garden: pearlwort (Sagina procumbens) sprouts from cobblestones along the Quai de Seujet, and smooth rupturewort (Herniaria glabra) can be found in Petit-Saconnex. Red hemp nettle (Galeopsis ladanum var. angustifolia) and Alpine Willowherb (Epilobium dodonaei) grow on the limestone pebbles that make up railway beds leading in and out of the city. (KS)