Breeding System of Ruellia succulenta Small (Acanthaceae)

Abstract

This study examines the breeding system of Ruellia succulenta (Acanthaceae), an herbaceous perennial found in the pine rockland habitat of southern Florida. Hand pollination treatments were performed on 75 plants, 25 from each of three sites. Treatments applied to test plants included: 1) control (no manipulation), 2) anthers-removed, 3) self-pollinated, and 4) cross-pollinated. The pollination protocol investigated facultative autogamy, apomixis, and self-compatibility. Fruit set and seed number per fruit were recorded. In addition to determining breeding system, the data were used to evaluate inbreeding depression at the earliest life history stages (i.e., fruit and seed set), and to identify the mechanism of self-pollination. Results showed R. succulenta to be fully self-compatible and facultatively autogamous. Plants were unable to set fruit without pollen deposition, indicating the lack of apomixis. There is no evidence of inbreeding depression in fruit set or seed set for the self- vs. cross-pollinated treatments. The mechanism of autofertility appeared to be delayed self-pollination as the corolla abscised and the anthers were dragged past the persistent stigma.