Hibiscus dasycalyx

Described only in 1968, and even then from a handful of sites in the bottomlands of east Texas — Houston, Trinity, and Cherokee counties, along the Neches, Angelina, and Trinity rivers. The total wild population has been estimated in the low thousands. Whole years of botanical fieldwork in the southeast have turned up fewer plants than a single good nursery bed.
It lives in a strange and specific habitat: seasonally flooded sloughs and oxbow margins, often threaded through the pimple-mound microtopography peculiar to east Texas bottomlands. The plants stand in spring floodwater for weeks, then ride out August on cracked clay. Multiple stems rise from a thick woody base to four or five feet, carrying the narrow linear leaves that distinguish this species at a glance from its showier kin. Saucer-sized flowers open one at a time from midsummer, ivory white with a deep maroon throat, the calyx behind them softly pubescent — dasycalyx meaning “hairy cup.”
The threats are habitat loss, of course, but also something quieter and more genetic. Hibiscus laevis is common, aggressive, and freely hybridizes wherever the two ranges touch, diluting the dasycalyx line within a few generations. Some botanists consider this the more pressing threat. Federally listed as threatened in 2013, which means it cannot cross state lines. South Carolina and in-person purchase only.
Full sun and moisture. It will take wet feet, irrigated borders, or anywhere in between.