Overview
Polynesian Arrowroot (Tacca leontopetaloides), known traditionally as pia across eastern Polynesia, is a fascinating perennial geophyte belonging to the yam family (Dioscoreaceae). Renowned among ethnobotanists and horticulturists for its extraordinary, otherworldly floral morphology, it produces an architectural inflorescence crowned with large maroon-green bracts and dozens of long, trailing whisker filaments resembling the tentacles of a jellyfish or a bat’s face. Carried intentionally aboard ancient voyaging outrigger canoes as a primary ‘canoe plant,’ it provided an indispensable staple carbohydrate that sustained island civilizations across Oceania.
Biology and Physical Characteristics
Tacca leontopetaloides sprouts each wet season from a rounded, potato-like underground tuber with a thin, pale yellowish-brown rind and crisp white starchy interior. From the tuber emerge one to three enormous, deeply tripartite leaves borne on tall, fluted petioles, spreading into delicate, deeply lobed emerald blades. In late summer, the plant shoots up a massive central flowering scape terminated by a dense umbel of 20 to 40 nodding greenish-purple flowers. Surrounding the flower cluster are several broad, leafy bracts accompanied by numerous sterile, thread-like bracteoles that droop downward up to 10 inches (25 cm) like trailing whiskers, functioning as landing ladders for crawling pollinating insects.
Behavior and Ecology
Thriving in the harsh, salt-laden microclimates of tropical coastlines, Polynesian arrowroot exhibits high tolerance for saline breezes, calcareous coral sands, and prolonged dry spells. During dry or cooler months, the above-ground foliage completely senesces, allowing the plant to survive subterranean dormancy buffered against extreme coastal weather. The curious whisker-like bracteoles and foul-scented sap of the flowers attract small saprophagous dipteran flies and thrips that perform cross-pollination. Spherical green berries develop following fertilization, releasing ribbed seeds encased in spongy tissue that float across ocean lagoons to colonize distant atolls.
Conservation and Human Impact
Assessed as Least Concern due to its vast, naturalized pantropical distribution, Tacca leontopetaloides remains ecologically secure. Historically, the tubers were laboriously harvested, grated, soaked, and repeatedly rinsed in fresh water to leach out bitter, toxic taccalin compounds before being baked into nourishing puddings (such as Hawaiian haupia). While modern imported starches have reduced commercial cultivation, Polynesian arrowroot remains a treasured cultural heritage crop throughout the Pacific, celebrated in traditional ethnomedicine and cultivated globally as a prized botanical specimen.
Interesting Factoid
The bizarre, drooping whisker filaments of the Polynesian arrowroot flower can reach ten inches in length, acting like natural rope ladders that guide crawling coastal insects straight into the reproductive center of each bloom.
Last updated: October 2026