Our hardy Hibiscus species as ornamentals
As a common plant name, "Hibiscus" is more often applied to the showy tropical sorts, especially Hibiscus rosa-sinensis L., than to other species of the genus. There is, however, another equally showy group, the hardy herbaceous mallows, native mostly to the Eastern United States. This group includes Hibiscus moscheutos L., H. militaris Cav., H. coccineus (Medicus) Walter, H. grandiflorus Michx., H. lasiocarpus Cav., and their many garden hybrids. The various species in this group are commonly called Rose Mallows. They grow naturally in marshy areas of the Atlantic States from southern New England to Florida, also inland along rivers and lakes. Isolated populations appear in areas such as the Sacramento River Valley of California. The tall vigorous growth of Rose Mallow plants plus the abundantly produced, large, gaily colored flowers makes them a conspicuous and attractive feature of the vegetation. Hibiscus moscheutos most often occurs in almost pure stands along tidal rivers of the mid-Atlantic states. During the peak of flowering, late July to mid-August, these stands are a striking sight to behold. In spite of the large fleshy roots, Rose Mallow plants withstand transplanting easily even when in full flower. They are also readily groxvn from seed and will flower the first season if sown early. Unlike their woody tropical relatives, the Rose Mallows are herbaceous perennials, and the plants become somewhat coarse by the end of the growing season. They also lack the yellow and orange flower colors so prominent in many Hibiscus rosa-sinensis clones. Nevertheless, the various species have been cultivated as ornamentals in the United States since Colonial times. As cultivated plants they perform best when grown in good garden soil with moderate amounts of water.
Wilt, Crown, and Root Rot of Common Rose Mallow (Hibiscus moscheutos) Caused by a Novel Fusarium sp.
A new crown and root rot disease of landscape plantings of the malvaceous ornamental common rose mallow (Hibiscus moscheutos) was first detected in Washington State in 2012. The main objectives of this study were to complete Koch's postulates, document the disease symptoms photographically, and identify the causal agent using multilocus molecular phylogenetics. Results of the pathogenicity experiments demonstrated that the Fusarium sp. could induce vascular wilt and root and crown rot symptoms on H. moscheutos 'Luna Rose'. Maximum-likelihood and maximum-parsimony phylogenetic analyses of portions of translation elongation factor 1-α and DNA-directed RNA polymerase II largest and second-largest subunit indicated that the Hibiscus pathogen represents a novel, undescribed Fusarium sp. nested within the Fusarium buharicum species complex.
Germination ecology of Central Asian Stipa spp: differences among species, seed provenances, and the importance of field studies
Stipa-species are wide-spread in Central Asia, but sexual reproduction in the dry steppes is rare. To facilitate conservation and restoration of these important rangelands, we studied germination characteristics of three common Mongolian Stipa-species under field- and lab conditions. Seeds of Stipa krylovii, Stipa gobica and Stipa glareosa were sown at the study site in Southern Mongolia over two consecutive years during which period tests were carried out to ascertain whether competition or herbivory are the main constraints of seedling establishment. In addition, we tested germination and seed viability in the laboratory under two different temperature regimes (20/10°C and 8/4°C), as well as the effect of cold-stratification. The lab experiments also included S. krylovii seeds originating from three climatically different provenances. None of the three Stipa-species seedlings emerged during the first 2 years of the field study. However, after an unusually intense rain event in the third year, 3% of S. krylovii, 0.6% of S. glareosa and 0.1% of S. gobica seeds germinated in the study plots. The factors ‘sowing-year’ and ‘vegetation’ significantly affected seedling emergence, whereas grazing had no effect at all. Under laboratory conditions a high percentage of viable seeds of S. gobica and S. glareosa germinated at both incubation temperatures, and cold-stratification had no effect on germination or viability. Germination of S. krylovii seeds required warmer temperatures and cold-stratification had a positive effect. Such evidence for dormancy was more pronounced in seeds from the moister, northern provenances. Germination of Stipa-species in the field is rare and only possible under exceptionally moist conditions. Conservation should thus concentrate on steppe conservation rather than on restoration. Where artificial reseeding is necessary, differences among species and also among different seed provenances should be taken into account.