Status In Oklahoma, the number of dwarf pipeworts is declining as a result of fire suppression. Previously, the species was a Category 2 (58 FR 188; September 30, 1993), but currently has no Federal status.
Dwarf pipewort can be as either an annual or biennial plant. It flowers in mid-May.
Dwarf pipewort grows in acid seeps and glades in the sand hillsides in southeastern Oklahoma. It grows on granite outcrops in the Georgia Piedmont region. Populations are widely scattered, but single populations of dwarf pipewort usually have numerous individuals.
Populations of dwarf pipewort are scattered along the Piedmont of Georgia, the Ozarks of Arkansas, and the Coastal Plain of Oklahoma and Texas. Dwarf pipewort occurs in three southeastern Oklahoma counties: Atoka, Muskogee, and Pushmataha.
Because of its small size, dwarf pipewort can be difficult to find. It is easiest to locate in flower, when the clusters of white to gray-green betray its presence. Also, the growth of dwarf pipewort is highly dependent upon precipitation. In years of low rainfall, it may not be evident at sites where it was abundant in previous years. Ten-angled pipewort (E. decangulare) is the only other species of pipewort in Oklahoma. Unlike dwarf pipewort, it has white flowers and the flowering heads have long hairs.
Causes of Decline
Habitat loss, as a result of wetland draining, is a serious threat to populations of dwarf pipewort. Natural disturbances, such as fire, are also necessary for such a small plant to persist. In the absence of fire, neighboring vegetation will grow taller than dwarf pipewort and shade it out. Fires help to remove competing vegetation.
Known populations should be protected from wetland conversion and draining. Natural disturbance regimes should also be reestablished at sites harboring dwarf pipewort.
Dwarf pipeworts are small (approximately 2-4 inches [5-10 cm] tall) and grasslike in appearance. Leaves are in tufts that appear to grow directly out of the ground. They are erect, thin, pale green, hairless (=glabrous) and up to 1 3/8 (3.5 cm) inches long and 1/32 inch (1 mm) wide. Each leaf has three distinct veins. Inflorescences are composed of minute flowers in a tight cluster (=head) at the apex of a stalk (=peduncle). There may be up to 25 peduncles per plant. Each peduncle grows to approximately 4 inches (10 cm) in height. The basal sheath is approximately 1 inch (2.5 cm) tall. Heads are spherical or hemispherical with a few hairs or hairless. Flowers white to gray-green with both a calyx and corolla. Sepals and petals number either two each or three each. Flowers are imperfect (=some flowers have stamens but no pistils, while others may have pistils and no stamens). Both types of flower generally occur on the same plant. There twice a s many stamens as petals. Pistils have two or three stigmas, one style, and a one-, two-, or three-celled ovary.