Plant of the Week
Drummond’s yellow-eyed grass (Xyris drummondii Malme)
By Ken L. Gordon, Botanist, National Forests in Mississippi
Drummond’s yellow-eyed grass is a small summer and fall flowering species that occurs in open, sunny pinelands and pitcher-plant flats and bogs. In this habitat, it grows in full sun in the wettest sites where the peat or sand substrate remains moist throughout the year. Its short leaves (3-8 cm long) are arranged like a fan (like Iris) Like other members of its genus, its small yellow flowers open one at a time in a densely crowded cone-like head. The head with its brownish or brown and green-cupped bracts superficially resemble tiny “pine-cones”. Drummond’s yellow-eyed grass superficially resembles two other small species of yellow-eyed grass such as X. flabelliformis and X. brevifolia, but can be differentiated from both by its late blooming period (the other two are spring or early summer bloomers) and by the chestnut-brown patch at the base of each leaf, just below the juncture of the tiny white roots. This latter characteristic can be confirmed in the field by brushing away the soil around the base of the leaves to expose the chestnut patch (about 2 mm wide) which is clearly visible without magnification.
Drummond’s yellow-eyed grass occurs across a narrow range in the Coastal Plain from southeast Georgia to the Florida Panhandle, south Alabama, south Mississippi, southern Louisiana, and adjacent East Texas. Within this range, the species occupies habitat that requires frequently recurring fire to maintain the open conditions necessary for its survival. Also critical to survival is maintenance of the high water table. This species can tolerate logging but not drainage. The most striking impediment to its continued survival is the conversion of its very specific habitat to other uses such as clearing for agriculture, pond construction, or residential development. The hydrology of these very wettest bogs is dependant on “perched water tables” in which water from surrounding sand hill forestland is slowly released through horizontal movement along an impervious soil layer to emerge into a “hillside” seepage bog.
Drummond’s yellow-eyed grass, like other rare species that occur in wetland communities of the Atlantic and Gulf coastal plains, appears to be dependent on fire disturbance for periodic removal of competing vegetation. Little is known, however, about the frequency and intensity of fires it depends on for its survival. The species appears to tolerate a wide range of burning regimes; flowering plants have been found in frequently burned areas (nearly annually) and in sites which have not burned in two to three decades. It is likely that occurrences in overgrown sites are in decline and that recruitment through sexual reproduction in deeply shaded sites is minimal to none.