Management and reintroduction efforts of Stylisma pickeringii (Torr.) Gray (Patterson bindweed) are limited by a lack of knowledge about its reproductive biology, including information about its seed germination and seedling development. The purpose of this study was to investigate its requirements for seed germination and its seedling development. To investigate seed requirements, seeds were harvested from Mason County over three growing seasons (1998, 1999 and 2000). For all three years, seeds of different colors (yellow, tan, maroon) were counted and germinated in petri dishes at 25 C with or without scarification. In 1999 and 2000, flowers were tagged and seeds were collected to determine how seed age and harvest date affect seed color. To investigate seedling development, seedlings were counted in the field and component parts (shoot, root, and underground shoot branching) were measured. Seed germination was different depending on seed color with yellow being the highest (55-96%) and maroon being the lowest (0%). Also, the seed coat inhibited germination as scarification increased germination. Effects of seed age and harvest date on seed color were inconclusive. The highest seedling density recorded was 1.8 plants/m2. For seedling development, S. pickeringii develops an extensive taproot before developing its shoots. Its shoot branches originate 7.2 cm beneath the soil surface. This research has provided knowledge about the seed and seedling biology of S. pickeringii, which will be useful in the management of this species.

Key words: Convolvulaceae, endangered plant, germination, Stylisma pickeringii