Helia alata

Native to Trinidad and northern South America, this annual herb has upright, four-angled stems and opposite, broad leaves. Terminal flowering branches carry pale green, fleshy, bell-shaped blossoms, often arranged along one side of each branch. Bats pollinate the flowers. Nectar glands around the flowers attract ants that protect them from herbivorous insects. Colonies nesting in the hollow stems of dead plants can help protect nearby living plants. Brown capsules develop inside the persistent calyx and contain many tiny seeds. As conditions dry, the capsule valves bend outward, allowing the wind to carry the seeds away. Photographed in Colombia.