Marathrum foeniculaceum.

Botanical name: 

Marathrum foeniculaceum Humb. & Bonpl. Podostemaceae.

Mexico and New Granada. This plant resembles seaweed and grows in the rivers of Veraguas. Its young leaf-stalks, when boiled, have a delicate flavor not unlike that of French beans.

Sturtevant's Edible Plants of the World, 1919, was edited by U. P. Hedrick.