Belongs within: Rubus.
The hairy blackberry
Published 12 May 2025
Readers of this site will hardly need to be told that the taxonomic diversity of our planet’s biota can be overwhelming. Hundreds of thousands of species have been described to date; hundreds of thousands perhaps remain yet to be described. But even the most ardent of taxonomist may find themselves looking at some particular groups and wondering if, at some point, the process of taxonomic description should just stop.
This is Rubus vestitus, one of a surprising number of species of blackberry. Rubus vestitus is native to northern Europe, and has also been introduced to southeastern Australia and northwestern North America. Like other blackberries, R. vestitus shrubs have a biennial growth habit. In the first year of growth, the plant produces vegetative, usually arching (sometimes prostrate) stems known as primocanes that become rooted at the tip towards the end of the season. Flowering stems (floricanes) are produced in the second year of growth from leaf axils of the primocane. The rooted tips of the primocane may give rise to vegetative canes of their own while new primocanes also develop from the initial crown. In this way, blackberries spread vegetatively to produce dense thickets. Rubus vestitus is further characterised by palmate, pedate leaves with three to five dull green leaflets that are hairy above and below, and inflorescence axes bearing densely erect pubescence (Evans et al. 2007). Both red- and white-flowered variants of R. vestitus are known.
The taxonomic challenge with blackberries results from the fact that they are largely apomictic—that is, the embryo of a new seed is typically produced parthenogenetically. The flower still requires fertilisation to set seed* but, in the majority of cases, the pollen parent does not contribute to the resulting offspring. As a result, populations of blackberries largely multiply asexually and lineages tend to maintain small but stable differences. Because gene flow is limited, any attempt to subdivide populations of apomictic taxa into ‘species’ is limited solely by the patience and/or obsession of the researcher.
*Flowering plants exhibit a nightmarishly complicated system of double fertilisation. A pollen grain landing on a flower’s stigma releases not one but two sperm cells, each of which fertilises a separate cell in the ovule. One of these cells develops into the embryo of the resulting seed, the other produces the endosperm. In blackberries, the endosperm is still produced as the result of fertilisation even if the embryo is not.
Blackberries are a prime exemplar of this issue. Literally hundreds of species have been described in the genus Rubus, some of them restricted to extremely small areas. Not all Rubus species are blackberries, of course, but blackberries are certainly the genus’ most challenging sector. Many sources will deal with the issue by simply referring to blackberries as a whole as the ‘Rubus fruticosus aggregate’, eliding further subdivisions. However, this approach obscures the manner in which species may exhibit very real differences. Rubus vestitus, for instance, is somewhat unusual among blackberries in that it prefers calcareous or clay soils and is only rarely found growing in acidic substrates. It is commonly found growing in shady woodlands, forest margins and scrub (Taylor 2005). Different blackberry species may respond differently to control measures where they are regarded as problem weeds, and ways of dealing with one may not adequately deal with another. It is all well and good to suggest that at some point taxonomic precision might devolve into simple pedantry, but it is far from simple to establish where that point might be.
Systematics of Rubus section Rubus
<==Rubus sect. Rubus subsect. HiemalesES07
|--R. ser. DiscoloresES07
| |--R. anglocandicans Newton 1977ES07
| |--R. armeniacusES07
| `--R. ulmifolius Schott 1818ES07
| |--R. u. var. ulmifoliusES07
| `--R. u. var. anoplothyrsus Sudre 1909ES07
|--R. (ser. Hystrices) phaeocarpus Watson 1937ES07
|--R. ser. MicantesES07
| |--R. erythrops Edees & Newton 1978ES07
| `--R. leightonii Lees ex Leight. 1841ES07
|--R. (ser. Radulae) echinatus Lindl. 1829ES07
|--R. ser. RhamnifoliiES07
| |--R. cissburiensis Barton & Ridd. 1931ES07
| |--R. polyanthemus Lindeb. 1883ES07
| |--R. riddelsdellii Rilstone 1950 [=R. riddelsdelli]ES07
| `--R. rubritinctus Watson 1956ES07
|--R. (ser. Sylvaticae) laciniatus Willd. 1806ES07
`--R. ser. VestitiES07
|--R. leucostachys Schleich. ex Sm. 1824ES07
`--R. vestitus Weihe in Bluff & Fingerh. 1825ES07
*Type species of generic name indicated
References
[ES07] Evans, K. J., D. E. Symon, M. A. Whalen, J. R. Hosking, R. M. Barker & J. A. Oliver. 2007. Systematics of the Rubus fruticosus aggregate (Rosaceae) and other exotic Rubus taxa in Australia. Australian Systematic Botany 20: 187–251.
Taylor, K. 2005. Biological flora of the British Isles: Rubus vestitus Weihe. Journal of Ecology 93: 1249–1262.