In Botany it means that it adapts or prefers the muddy or swampy terrain. It refers to the condition of the plants that develop in this type of soil. Etymologically the word means that it prefers swamps, which prefers hollows or muddy land.
From the Greek helos , hollow, marshy place and philia , inclination . Preference of some plant formations for wetlands and swampy areas, developing above water.