Rubus is a large and diversegenus of flowering plants in the rose family,Rosaceae, subfamilyRosoideae, most commonly known asbrambles.[3][4][5][6] Fruits of various species are known asraspberries,blackberries,dewberries, andbristleberries. It is a diverse genus, with the estimated number ofRubus species varying from 250 to over 1000, found across all continents except Antarctica.[7]
Most of these plants have woody stems with prickles like roses; spines, bristles, and gland-tipped hairs are also common in the genus. TheRubusfruit, sometimes called a bramble fruit, is anaggregate ofdrupelets. The termcane fruit orcane berry applies to anyRubus species orhybrid which is commonly grown with supports such as wires or canes, including raspberries, blackberries, and hybrids such asloganberry,boysenberry,marionberry andtayberry.[8] The stems of such plants are also referred to ascanes.
Bramble bushes typically grow asshrubs (though a few areherbaceous), with their stems being typically covered in sharpprickles.[9] They grow long, arching shoots that readily root upon contact with soil,[10] and form a soilrootstock from which new shoots grow in the spring.[11] The leaves are eitherevergreen ordeciduous, andsimple,lobed, orcompound.[9] The shoots typically do not flower or setfruit until the second year of growth (i.e. they arebiennial).[11] The rootstock isperennial.[12] Mostspecies arehermaphrodites with male and female parts being present on the same flower.[9] Bramble fruits areaggregate fruits formed from smaller units calleddrupelets.[11]
Around 60–70% of species ofRubus arepolyploid (having more than two copies of each chromosome), with species ranging inploidy fromdiploid (2×, with 14 chromosomes[13]) to tetradecaploid (14×).[14]
Rubus is very complex, particularly within theblackberry/dewberrysubgenus (Rubus), with polyploidy,hybridization, and facultativeapomixis apparently all frequently occurring, making speciesclassification of the great variation in the subgenus one of the grand challenges ofsystematic botany. In publications between 1910 and 1914, German botanistWilhelm Olbers Focke attempted to organize the genus into 12 subgenera, a classification system that since became widely accepted, though modern genetic studies have found that many of these subgenera are notmonophyletic.[7]
Some treatments have recognized dozens of species each for what other, comparably qualified botanists have considered single, more variable species. On the other hand, species in the otherRubus subgenera (such as theraspberries) are generally distinct, or else involved in more routine one-or-a-few taxonomic debates, such as whether the European and American red raspberries are better treated as one species or two (in this case, the two-species view is followed here, withR. idaeus andR. strigosus both recognized; if these species are combined, then the older nameR. idaeus has priority for the broader species).
The classification presented below recognizes 13 subgenera withinRubus, with the largest subgenus (Rubus) in turn divided into 12sections. Representative examples are presented, but many more species are not mentioned here. A comprehensive 2019 study found subgeneraOrobatus andAnoplobatus to bemonophyletic, while all other subgenera to beparaphyletic orpolyphyletic.[16]
The genus has a likely North American origin,[16] with fossils known from theEocene-agedFlorissant Formation of Colorado, around 34 million years old.[17]Rubus expanded into Eurasia, South America, and Oceania during theMiocene.[16]Fossil seeds from the earlyMiocene ofRubus have been found in theCzech part of theZittau Basin.[18] Many fossil fruits of †Rubus laticostatus, †Rubus microspermus and †Rubus semirotundatus have been extracted from bore hole samples of theMiddle Miocene fresh water deposits inNowy Sacz Basin,West Carpathians,Poland.[19]
Molecular data have backed up classifications based on geography and chromosome number, but followingmorphological data, such as the structure of the leaves and stems, do not appear to produce a phylogenetic classification.[20]
The term "hybrid berry" is often used collectively for those fruits in the genusRubus which have been developed mainly in the U.S. and U.K. in the last 130 years. AsRubus species readily interbreed and areapomicts (able to set seed without fertilisation), the parentage of these plants is often highly complex, but is generally agreed to include cultivars of blackberries (R. ursinus,R. fruticosus) and raspberries (R. idaeus). The British National Collection ofRubus stands at over 200 species and, although not within the scope of the National Collection, also hold many cultivars.[21][22]
The generic name means blackberry inLatin and was derived from the wordruber, meaning "red".[24]
The blackberries, as well as various otherRubus species with mounding or rambling growth habits, are often calledbrambles.[25] However, this name is not used for those like the raspberry that grow as upright canes, or for trailing or prostrate species, such as most dewberries, or various low-growing boreal, arctic, or alpine species. The scientific study of brambles is known as "batology"."Bramble" comes from Old Englishbræmbel, a variant ofbræmel.[5]
^ab"Rubus L."Plants of the World Online. Board of Trustees of the Royal Botanic Gardens, Kew. 2021.Archived from the original on 31 March 2023. Retrieved4 September 2021.
^Acta Palaeobotanica – 43(1): 9-49, January 2003 – Early Miocene carpological material from the Czech part of the Zittau Basin – Vasilis Teodoridis
^Łańcucka-Środoniowa M.: Macroscopic plant remains from the freshwater Miocene of the Nowy Sącz Basin (West Carpathians, Poland) [Szczątki makroskopowe roślin z miocenu słodkowodnego Kotliny Sądeckiej (Karpaty Zachodnie, Polska)]. Acta Palaeobotanica 1979 20 (1): 3-117.
^Lawrence A. Alice & Christopher S. Campbell (1999). "Phylogeny of Rubus (rosaceae) based on nuclear ribosomal DNA internal transcribed spacer region sequences".American Journal of Botany.86 (1). Botanical Society of America:81–97.Bibcode:1999AmJB...86...81A.doi:10.2307/2656957.JSTOR2656957.PMID21680348.
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