Botanical Characteristics:
– Bramble bushes are shrubs with prickly stems and long, arching shoots that root upon contact with soil.
– Leaves of Rubus can be evergreen or deciduous, and simple, lobed, or compound.
– Shoots typically do not flower or set fruit until the second year.
– Most Rubus species are hermaphrodites with male and female parts on the same flower.
Taxonomy and Classification:
– The classification of Rubus is complex, especially within the blackberry/dewberry subgenus.
– There are 13 subgenera within Rubus, with the largest subgenus divided into 12 sections.
– Challenges in species classification arise from polyploidy, hybridization, and apomixis.
– Different treatments have recognized varying numbers of species within Rubus.
Evolution and Distribution:
– Rubus likely originated in North America around 34 million years ago.
– The genus expanded into Eurasia, South America, and Oceania during the Miocene.
– Fossil seeds of Rubus species have been found in various regions.
– Molecular data supports classifications based on geography and chromosome number.
Species and Cultivars:
– Rubus species include raspberries, blackberries, and hybrids like loganberry and boysenberry.
– The British National Collection of Rubus houses over 200 species and cultivars.
– Blackberries and other Rubus species with mounding growth habits are often referred to as brambles.
– Hybrid berries like loganberry and boysenberry have been developed in the US and UK.
Resources and Publications:
– Mitchell Beazley published a book on Rubus, and Trees and Shrubs Online is a resource for Rubus information.
– Scientific studies on Rubus include research on genomes, evolution, and phylogeny.
– Online resources like Wikimedia Commons and the Rubus Species website offer detailed information.
– Publications in journals like The American Journal of Botany and The Garden discuss various aspects of Rubus.