The slender spike-rush is a type of aquatic plant with narrow stems and small spike-like flowers. Synonyms for this plant include the marsh arrowgrass, needle spike-rush, and water fanwort. The marsh arrowgrass is a plant that grows in marshes and along the edges of streams. It has long, narrow leaves that are often used to weave baskets. The needle spike-rush is a small plant that is found in wetlands and around ponds. The water fanwort is a type of aquatic plant that is often used in aquariums and ponds. All of these plants are similar in appearance and have similar habitats, making them useful to identify for conservation and restoration efforts.