SPATIAL RELATIONSHIPS OF HELIANTHUS-PARADOXUS (COMPOSITAE) AND ASSOCIATED SALT-MARSH PLANTS

Helianthus paradoxus (the puzzle sunflower, Compositae) is a rare spec ies, only found along Leon Creek in the Diamond Y Springs Preserve, in closely associated areas near Fort Stockton, Texas (31 degrees 10'N, 102 degrees 45'W), and in several locations in central and eastern New Mexico. In the Diamond Y Springs Preserve, it is found in specific ha bitats and exhibits high spatial fluctuations in density and cover. It does not occur in Larrea tridentata (creosote bush) communities on sh allow upland soils or in Prosopis glandulosa (honey mesquite) communit ies on deep upland soils. As one descends slightly in elevation from d ry P. glandulosa upland communities into the salt marsh, a Sporobolus airoides (alkali sacaton) grassland is encountered. The next major com munity is a Distichlis spicata (saltgrass) grassland. Helianthus parad oxus usually is found with various cover values ranging from 0 to 70% or at densities from 0 to 23 plants/0.1 m(2), associated with D. spica ta. Helianthus paradoxus usually is not found in the deepest, saturate d soils in the lowest part of the salt marsh associated with the drain age where Scirpus olneyi (bulrush) typically is the dominant species.