Reproductive Biology of Several Bromegrasses (Bromus): Breeding System, Pattern of Fruit Maturation, and Seed Set

Five species of Bromus were tested for self‐fertility when bagged. Bromus inermis was self‐incompatible. Bromus tectorum, B. kalmii, B. ciliatus, and B. latiglumis were capable of self‐fertilization. Further evidence from flowering behavior suggested that B. tectorum almost always self‐pollinated and that the remaining self‐fertile species sometimes outcrossed. Florets in different positions on a spikelet varied in the proportion that set seed. Open‐pollinated B. inermis plants had lower seed set than the self‐fertile species, in agreement with the pattern in a variety of hermaphroditic plants.