Hymenachne is a genus of widespread wetlands plants in the grass family. They may be known commonly as marsh grasses. They are distributed in tropical and subtropical regions of Asia, the Americas, and the Pacific Islands.
Wetland grass provides a food source for cattle and other wildlife because it has protein.
Hymenachne aquatic plants frequently found in marshes and other wet habitats. Their stems are spongy with aerenchyma tissue. The longest stems can reach 4 meters. They are perennial, sometimes with rhizomes.
Photo: Yishun Pond, Singapore 
Origin: New Guinea
Prefers tropical but will grow in warm subtropics as long as you keep the water up. Tapeinochilos densum thrives in rich moist to boggy soil.
Each inflorescence of this spiral ginger family member somewhat resembles a pineapple, hence the common name of pineapple ginger. In tropical to semi-tropical areas, this plant blooms throughout the year.
Green leaves wrap spirally around plant stems.
Photos: HortPark, Singapore, 20130629