Conifer vs. Angiosperm
An idea long prevailed that angiosperm trees, having superior reproductive capability compared to conifers, displaced them to extreme habitats considered unfavorable to angiosperms. A study of extant conifers supports the notion that in productive regions of the tropics, leaf structure (needles instead of wide leaves) and vascular structure (tracheids instead of vessels) puts conifers at a competitive disadvantage with angiosperms in terms of growth speed. There is evidence that some conifers became extinct as a result. But the “slow seedling” hypothesis does not account for the broad range of habitats occupied by modern conifers. The three most successful conifer families are Pinaceae (Northern Hemisphere), Podocarpaceae (Southern Hemisphere), and Cupressaceae (global). Various distinct mechanisms employed by conifers, allow them to escape direct confrontation with angiosperm competitors. Besides their conservative functional traits that allow them to endure and survive stress in extreme habitats, conifers successfully: 1) compete against angiosperms for resources once they are mature, 2) colonize sites following a disturbance and, 3) tolerate low-intensity fires.
International Journal of Plant Sciences, 173 (6) 673-694
An Improved USDA Climate Zone Map
The USDA hardiness zone map is based on mean annual minimum temperature. The most current map was published in 2012 and is based on data from 8000 weather stations between 1976-2005, taking into account elevation and proximity to shorelines. The data is averaged over a relatively recent chunk of time because of the known warming trend, but may not
reflect accelerating change well enough. A current study uses more of the historical data, focusing on trends in various regions to come up with a better prediction of how the zones should be described. This mathematical modeling strategy suggests that, in general, winters are warming up faster than summers. The southwest United States is demonstrating the least change in average minimum temperatures and the southern Appalachians are showing the most change. The data also suggests that annual minimum temperatures are, on average, already 1.2°C higher than shown in the 2012 USDA zone map. This would shift one-fifth of the nation into another climate zone. The method is expected to be applicable to precipitation and other climatic variables and may provide a more useful climate zone map in the future.
Advances in Meteorology, Vol 2012, article ID 404876
Plants Assist in Materials Science Research
“There is plenty of room at the bottom,” is a famous quote by the physicist Richard Feynman in his 1959 Cal Tech lecture, encouraging scientists to think small—really small. Now it appears that plants and fungi can help with that. Silver nanoparticles, used in medicine, optics, and electronics, can be produced within minutes, at room temperature, in an environmentally friendly way without toxic chemicals, by the reduction of silver nitrate in a liquid medium containing various leaf extracts. The latest plant to be used for the process is the strawberry tree (Arbutus unedo); however success has also been achieved using other plant leaf extracts, fungi, and even humic acids. There remains the question though of how environmentally friendly the nanoparticles themselves are once in the environment.
Materials Letters, 76: 18-20
Potential Help for Depression Patients
Chemicals from the South African species Crinum and Cyrtanthus and several daffodils have an effect on the part of the human brain involved in clinical depression. Studies that show the chemicals can traverse the blood-brain barrier are promising—a test most potential drugs fail. This is just the first stage of lengthy testing procedures, so it will be many years before a drug
will be available.
Journal of Pharmacy and Pharmacology, 64 (11) 1667-1677