Niche Partitioning, and Phenological and Morphological Separation Between Two Sunflower Species

Two species of sunflower (Helianthus grosseserratus and H. rigidus) were investigated to determine phenological, habitat, and morphological separation between them. The two species had overlapping distributions across a habitat gradient and also overlapped in flowering times, although H. rigidus flowered earlier than H. grosseserratus. The two species achieved their maximum abundance on different portions of a topographic gradient, with H. rigidus being more abundant than H. grosseserratus on upper and middle slopes and H. grosseserratus being more abundant on lower slopes and depressions. The two species had relatively distinctive morphologies.