The snowbells (Styrax L.) are a group of flowering shrubs and trees distributed throughout the warm-temperate regions of the northern hemisphere. In all, there are about 120 species, of which only Styrax japonicus Sieb. & Zucc. (Japanese snowbell) and its cultivars are currently of commercial significance. Other species may also posses desirable horticultural traits that could be valuable on their own merit, or used in plant improvement programs. Currently there is little information regarding asexual propagation of the lesser known species. The results herein show that propagation of a diverse collection of Styrax(15 taxa) is possible by stem cuttings. However, species and cultivars within a species do not respond to auxin treatment similarly. The percentage of rooting of many taxa was improved when cuttings were treated with 3000 or 8000 ppm (0.3% or 0.8%) of the potassium salt of indolebutyric acid (K-IBA). However, rooting was unaffected by K-IBA treatment in some taxa, while rooting was negatively affected by K-IBA in others. Additionally, the number of roots produced per rooted cutting were affected by K-IBA treatment. In some instances, K-IBA increased the number of roots per rooted cutting. However, in most of the taxa, root number was unaffected.
Jason J. Griffin and F. Todd Lasseigne
Donglin Zhang, F. Todd Lasseigne and Michael A. Dirr
China, E.H. Wilson's “Mother of Gardens”, is a large untouched resource of ornamental plants to this day. Southeastern gardens and arboreta teem with plants from China, which boasts the most diverse temperate flora in the world with more than 30,000 species described. Because of China's unique geography, climate, and floristic similarities to the southeastern United States, many of these ornamental plants should be adaptable. Based on studies of the phytogeography, floristics, history of plan; hunting, and performance of plants already introduced into cultivation from central and southeastern China, ≈500 potentially “new” species of Chinese woody plants are presented for ornamental evaluation. Characterization of the species' geography and climatic preferences in China will allow horticulturists to more accurately predict the species' performance throughout the Southeast. Zone maps exist for the United States and China that equate geographic areas on a temperature basis. However, these zone maps do not reflect the wide microclimatic differences (such as those contributed by elevation) that occur in the climatic zones. The results of this survey should enhance interest in the wonderful diversity of Chinese plants. Maps of areas already explored in the past (George Forrest, Ernest H. Wilson, and other contemporary explorers) as well as maps of suggested areas which have not been fully botanized are presented for review.
F. Todd Lasseigne, Timothy J. Smalley, Harry A. Mills and William P. Miller
Ilex crenata `Helleri' (Helleri holly) can experience landscape establishment problems in the Southeast. Since aluminum toxicity is a major problem in acid soils of the Southeast, this experiment studied the effects of aluminum on Helleri holly grown in solution culture. A modified Hoagland's solution contained low phosphorus concentrations (32 μM), a 1:1 NH4+:NO3 - nitrogen ratio, and aluminum treatments consisting of 0, 222, 444, 889, and 1332 μM Al supplied at equal ratios from AlCl3·6H2O and Al2(SO4)3·18H2O. The MINTEQA2 (version 3.11) chemical speciation model was used to predict activity of ions in solution. Shoot growth and root length were not affected by aluminum after 12 weeks in solution culture. Total plant nutrient uptake was monitored weekly. Results indicate that Helleri holly does not take up aluminum ions even though NH4 + is the preferred nitrogen source. Other studies have shown increased aluminum toxicity effects when NH4 + is the preferred nitrogen source.
F. Todd Lasseigne, Stuart L. Warren, Frank A. Blazich and Thomas G. Ranney
Eight taxa of Salvia L., representing broad geographic origin and diversity within the genus, were grown under long day conditions for 36 d at 15-h days of 20, 25, 30, 35, or 40 °C and 9-h nights of 15 or 25 °C. Taxa of European origin displayed broader tolerance to high day temperatures (DTs) with the lowest relative reduction in growth and net photosynthesis (Pn) occurring at DTs 30 °C or greater compared with those native to North and South America. Salvia splendens Sell. ex Roem. & Schult. (scarlet sage) was particularly intolerant of high temperatures with all plants dying at days of 40 °C. All plants of S. nemorosa L.‘Ostfriesland’ (‘Ostfriesland’ wood sage), S. pratensis L. (meadow sage), and S. × sylvestris L. ‘Mainacht’ (‘May Night’ salvia) survived at days of 40 °C with no visual signs of injury, whereas all other taxa except S. splendens exhibited stunted, contorted growth with foliar chlorosis and necrosis at 40 °C. Day temperature exerted the primary effect on top growth, root growth, and Pn of all taxa. Night temperature effects were significant for some taxa but were of less importance than day temperature.