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Richard T. Olsen, Thomas G. Ranney, and Zenaida Viloria

Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F

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Marietta Loehrlein and Sandy Siqueira

Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F

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Robert J. Griesbach

Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F

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Hongmei Ma and Margaret Pooler

Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F

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Eric Stafne, Jon Lindstrom, and John Clark

Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F

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Keri Jones and Sandra Reed

Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F

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Zhanao Deng and Brent Harbaugh

Poster Session 7—Ornamental Plant Breeding 18 July 2005, 1:15–2:00 p.m. Poster Hall–Ballroom E/F

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Bruce L. Dunn and Jon T. Lindstrom

Controlled reciprocal crosses between Trichostema lanatum Benth. (section Chromocephalum F.H. Lewis) with Trichostema arizonicum A. Gray (section Paniculatum F.H. Lewis) and Trichostema purpusii Brandegee (section Rhodanthum Lewis) were successful in generating the first artificial hybrids in the genus. Crosses where T. lanatum was used as the female were unsuccessful. Leaf and floral morphology among the hybrids was typically intermediate. Female sterility was seen in the T. arizonicum × T. lanatum hybrids, and these hybrids also produced abnormally small, nonviable pollen grains. Propagation procedures are also presented. Although these species may be in different sections, their crossability suggests that they are closely related.

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Clara E. Trueblood, Thomas G. Ranney, Nathan P. Lynch, Joseph C. Neal, and Richard T. Olsen

Although Hypericum androsaemum L. is a valuable landscape plant, the species can be weedy and potentially invasive in certain locations. Infertile, non-invasive cultivars of H. androsaemum with desirable ornamental features would be ecologically beneficial and valuable for the horticultural industry. The male and female fertility of 10 triploid H. androsaemum, developed with a combination of variegation and foliage colors, was investigated under greenhouse (controlled pollination) and field conditions (natural pollination). Male fertility was evaluated based on pollen viability tests (pollen staining and pollen germination). Female fertility was based on fruit set, seed set, germinative capacity of seeds, and number of seedlings produced for each flower. Although values for different measures of fertility varied among triploid clones, pollen germination was significantly reduced for all triploids and nine of the 10 triploids produced no viable seed. These results represent 100% failure of ≈171,000 potential fertilization events based on fertility levels of diploid controls. The remaining triploid clone produced two seedlings per flower compared with 260 seedlings per flower for the controls. However, the seedlings produced by the triploid clone died shortly after germination. This research documented that the triploid H. androsaemum tested are highly infertile with no measurable female fertility. These clones will provide ideal alternatives to fertile forms of H. androsaemum where invasiveness is a concern. These methods also provide a useful protocol for evaluating fertility of other taxa that are selected or developed as non-invasive cultivars of potentially weedy species.