Eriocaulon decangulare, commonly known as ten-angled pipewort, hat pin and bog button, is a monocotyledonous plant native to the eastern United States, Mexico and Nicaragua. The plant's distribution is quite irregular, with several disjunct populations and a discontinuous primary range. Most of its habitat in the United States runs along the Atlantic Coastal Plain, but some populations also occur in more mountainous regions. It is found in areas of relatively low elevation and the plant does not occur higher than 300 metres above sea level. This pipewort is found in peat and sand that is moist to wet and associated with savannahs, bogs, low pinelands, ditches and the banks of cypress domes.