Molecular reappraisal of relationships between Photinia, Stranvaesia and Heteromeles (Rosaceae, Maleae)

Photinia, Stranvaesia and Heteromeles are considered to be related genera belonging to the tribe Maleae of Rosaceae. Stranvaesia comprises five species distributed in eastern Asia while Photinia consists of about 30 species found in eastern Asia and Mexico. Heteromeles is a monotypic genus distributed in northwestern Mexico and southwestern US. Distinctions between these three genera rely on morphological features of leaves, flowers, and fruits, but some character states that are supposed to be diagnostic of Stranvaesia also occur in species of Photinia. In order to clarify the taxonomic delimitations of the three genera, sequences from one nuclear gene (PepC) and three intergenic chloroplast DNA regions (trnS-trnG, psbA-trnH and trnL-trnH) were used to estimate the phylogeny of Photinia, Stranvaesia and Heteromeles. All Maximum parsimony, maximum likelihood, and Bayesian analyses supported the conclusion that the evergreen species Stranvaesia davidiana should be merged into Photinia, and another two deciduous species S. amphidoxa and S. tomentosa should be transferred to the genus Pourthiaea. Additionally, one Photinia species P. bodinieri should be transferred into Stranvaesia. Finally, it is suggested that Heteromeles arbutifolia should be merged into Photinia. Taxonomic treatments have been made to those species mentioned above, three new combinations have been proposed and six lectotypes have been designated here.

Post-fire regeneration strategies and flammability traits of California chaparral shrubs

Fire behaviour is strongly influenced by fuel load and structure; however, efforts to describe fuel patterns have largely ignored differences among species or post‐fire regeneration strategies. In California chaparral, evergreen shrubs can be grouped into three post‐fire regeneration strategies that correlate with a wide variety of physiological and demographic characteristics including seasonal water status and the timing of reproduction in response to fire. To test if regeneration strategy is also associated with flammability, we compared the fuel loads and structure of two post‐fire seeders, Adenostoma fasciculatum and Ceanothus cuneatus, and two obligate resprouters, Heteromeles arbutifolia and Prunus ilicifolia. Species and post‐fire regeneration strategies did not differ in total fuel per area, or bulk density. The proportion of fuels smaller than 6 mm in diameter differed among species, but not consistently with regeneration strategy. However, species with a post‐fire seeding regeneration strategy had higher proportions of dead branches. We discuss how this difference could have arisen from evolutionary, demographic, or physiological processes.