Heart-leaved Water Plaintain: Rare, and getting rarer

A damp gravel bar in a tiny Adams County stream is dominated by eastern North America's largest plantain, the heart-leaved water plantain, Plantago cordata. The basal leaves can reach two feet across in exceptional specimens. It's also one of this region's rarest plants, and seemingly quickly becoming rarer.

Historically documented in ten Ohio counties, this plantain is now known from only three: Adams, Hardin, and Mahoning. Fortunately, all three populations are on protected lands.

I got to revisit two of the three sites this spring, after not seeing them for over a decade. While admittedly anecdotal recollections, my immediate sense upon seeing these sites again was that the populations had shrunk significantly since I had last seen them.

A flowering spike of Plantago cordata, bristling with elongate filaments capped by brownish anthers. While no one would call this a showy wildflower, its overall robustness and ornate architecture gives the plant a certain charisma.

Two giant plantains spring from the rocky bed of this headwater stream. Fortunately, the Arc of Appalachia has acquired this site and is monitoring the plants. There is no question that their ownership - and that of the other two sites, which are also owned by conservation organizations - gives the rare plantain a better long-term outlook.

Courtesy of the USDA Plant Database, here's a county-level distribution map of heart-leaved water plantain. The plant is long gone from many if not most of those green counties, and is now listed as endangered or some other category of imperiled in most of those states.

The reasons for the demise of this species of undisturbed wooded swamps and streams is not too tough to suss out. Habitat loss, and water quality degradation certainly must be the overriding factors in the plantain's decline. Heart-leaved water plantain apparently does not rebound well from logging or other large-scale disturbance, and much of the habitat in its range has been converted to agriculture.

Even sites that survive may be adversely impacted by land abuses further upstream in the watershed. Increased siltation may be a detrimental factor, as is greatly increased "flashiness": sudden and abnormally large water surges caused by removal of protective vegetation along stream banks, and rapid run off from farm fields or other forms of development.

Plantago cordata would be a good candidate for Federal listing - the rarest of the rare.