Rubus calvus H.E.Weber

The R. calvus complex – two species, three names

The complex of Rubus calvus consists of two species, which three names have been given to: R. calviformis, R. calvus and R. contractipes. So one of these is superfluous. The main differences of these two taxa can be described as followed:

Taxon A:

petiolule of the middle lateral leaflets 0-5 mm; terminal leaflet convex; serrature rather fine to mediocre; pedicels with numerous conspicuous glands often intermixed with gland tipped pricklets.

Taxon B:

petiolule of the middle lateral leaflets 7-11 mm; terminal leaflet ± flat; serrature very fine; pedicels with glands usually hidden in the hairs or some slightly longer, not conspicuous and no gland tipped prickles.

(NB. The color of the petals at the pictures of the living plant is actually pink but seems pale due to the exposure.)

Any of these characteristics can vary, even at the same plant, and none of them makes an absolute distinction. It is the combination of these characteristics and other ones (that can vary even more) which makes the decisive aspect of plants. The extremes are clear; taxon B has never long stalked glands or gland tipped pricklets on the pedicels and never very convex leaves in the middle part of the primocane and taxon A has never lateral leaves with petiolules of about 10 mm, but there is a section of overlap in most characteristics. The most stable characteristic is the stalked glands on the pedicels.

It is beyond discussion that the type of R. contractipes belongs to taxon A, while that of R. calviformis belongs to taxon B. The matter of debate is the type of R. calvus. If it belongs to taxon A Rubus calvus must be the correct name of this taxon, and R. contractipes is a later synonym then. If it belongs to taxon B it is a synonym of R. calviformis, which is published in the same article (WEBER 1982), but because Weber opted for the name R. calvus (WEBER 1988), he should be followed. Therefore we have to focus on the type of R. calvus.

A lectotype of R. calvus is in L and to my opinion this is clearly species A: the short stalked lateral leaflets and the long stalked glands with their strong almost pricklet-like stalks on the pedicels are typical for this taxon, just as the whole image of the plant.

Dr. Weber was so kind to send me a photo of the lectotype in his own collection, which has somewhat longer lateral pedicels, but further the plant does not differ. It is just a proof of my statement that this characteristic is variable at one and the same plant.

So my conclusion is that R. calvus belongs to the same taxon as R. contractipes and is its correct name. By consequence R. calviformis is the correct name of taxon B – just as Weber (1982) published in the very beginning, in his protologue of these two names.

Literature:

Weber, H.E. 1982. Einige bislang übersehene Brombeer-Arten der Sektion Corylifolii im westlichen Mitteleuropa (Gattung Rubus, Rosaceae). Osnabrück. Naturwiss. Mitt. 9: 85-98.

-       1988. Ergänzungen zur Rubus-Flora in Nordwestdeutschland. Osnabrück. Naturwiss. Mitt. 14: 139-156.

  • Taxon A - photo A.S. Troelstra
    Taxon A - photo A.S. Troelstra
  • Taxon A - photo A.S. Troelstra 2
    Taxon A - photo A.S. Troelstra 2
  • Taxon A primocane
    Taxon A primocane
  • Taxon A primocane leaf
    Taxon A primocane leaf
  • Taxon A primocane leaf 2
    Taxon A primocane leaf 2
  • Taxon A inflorescence
    Taxon A inflorescence
  • Taxon A pedicels
    Taxon A pedicels
  • Taxon B photo A.S. Troelstra
    Taxon B photo A.S. Troelstra
  • Taxon B photo A.S. Troelstra 2
    Taxon B photo A.S. Troelstra 2
  • Taxon B primocane
    Taxon B primocane
  • Taxon B inflorescence
    Taxon B inflorescence
  • Taxon B petiolules
    Taxon B petiolules
  • Taxon B primocane 2
    Taxon B primocane 2
  • Taxon B primocane 3
    Taxon B primocane 3
  • Taxon B primocane 4
    Taxon B primocane 4
  • Taxon B leaf
    Taxon B leaf
  • Taxon B inflorescence 2
    Taxon B inflorescence 2
  • Taxon B pedicels
    Taxon B pedicels
  • R. calvus lectotype in L label
    R. calvus lectotype in L label
  • R. calvus lectotype in L
    R. calvus lectotype in L
  • R. calvus lectotype in L petiolules
    R. calvus lectotype in L petiolules
  • R. calvus lectotype in L pedicels
    R. calvus lectotype in L pedicels
  • R. calvus lectotype in L 2
    R. calvus lectotype in L 2