Rubus auritus A. Beek & P.P. Ferrer, 2024

Ferrer-Gallego, P. Pablo & Beek, Abraham Van De, 2024, After the conservation of Rubus ulmifolius (Rosaceae), Phytotaxa 677 (3), pp. 289-297 : 292-296

4. Rubus auritus A. Beek & P.P. Ferrer , nom. nov., pro Rubus inermis Willdenow (1809: 548)

Lectotype ( Monasterio-Huelin & Weber (1996: 316), pro “ holotype ”; designated by Van de Beek & Widrlechner 2021):—[UNKNOWN], s.d. (B barcode B-W 09891-01 0).

Epitype (designated here):— NETHERLANDS, Veenendaal , Petenbos 6, 52.00908N / 5.54351E, 13 July 2023, A. Van de Beek 2023.04 ( B barcode [in process]; isoepitypes: L barcode [in process] and MAF barcode [in process]) (see Fig. 2 ) .

The whole plant unarmed. Primocane ( Fig. 3 ) roundish to obtuse angular, diameter 5–10 mm, in the sun dark brown red, with dense very short stellate hairs. Stipules linear 9–15 mm long, high (5–10 mm) inserted on the petiole. Petiole 4–7 cm long, with dense short stellate hairs. Leaves ( Fig. 4 ) 3-foliolate with lobate lateral leaflets, on strong stems partially 4–5-foliolate, serrature irregular, rather fine, sharp with long mucrons, irregularly rounded periodical, adaxially glabrous or with a few (0–4 pro cm 2) hairs, abaxially grey or greyish green, hardly to rather dense tomentose and with long simple hairs, soft on touch. Central leaflet ovate, elliptical, rhomboid or obovate, with a wedged or rounded base, gradually to rather abruptly short pointed to almost acute; width-length index 0.66–0.88. Length of the petiolule 16–26% of the length of the leaflet. Petiolule of the lateral leaflets 2–4 mm. Flowering branch angular, with dense very short stellate hairs. Leaves 3-foliolate, adaxially with long appressed hairs on the veins and outside these 0–25 hairs per cm 2 on the surfaces, abaxially green or grey tomentose, and with long hairs; serrature rather fine and regular, sharp. Peduncles slightly erect, densely short tomentose ( Fig. 5 ). Pedicels thick, 6–13 mm long. Sepals reflexed, grey tomentose. Petals ( Fig. 6 ) pink to pinkish red, ovate or elliptical, sometimes slightly obovate length 11–15 mm, width 5–9 mm, width-length index 0.45–0.66. Stamens longer than the yellow styles. Anthers glabrous. Ovaries with long hairs. Receptacle densely long hairy.

Rubus auritus , on the one hand, shows features that indicate a relation with R. ulmifolius , especially the shape of the inflorescence and the many short stellate hairs. However, on the other hand, it has such different characteristics that it certainly does not belong to that species. With its long procumbent primocanes, its leaves that are often 3-nate with deep lobate lateral leaflets with sharp serrature, its short petiolulated central leaflets with wedged or rounded base, it reminds of taxa of the North-American dewberries, the series Procumbentes Rydberg (1913: 430) . Seringe conceived the plant of R. inermis sensu Willdenow in the Botanical Garden in Berlin already as a variety of R. flagellaris Willdenow (1809: 549) : R. flagellaris var. inermis (Willd.) Seringe (1825: 559) . Both R. inermis and R. flagellaris grew in the Botanical Garden and were published by Willdenow from material that he collected there. Rubus auritus might be a stabilized hybrid of R. flagellaris , or one of other Procumbentes , with R. ulmifolius . This might also explain the North American origin that Willdenow (1809) claims. Molecular research may give more clarity about the precise taxonomic position of R. auritus .

Willdenow (1809: 548) published once again a R. inermis , based on a plant that grew in the botanical garden in Berlin. It is, as the name indicates, just like Pourret’s plant unarmed, but it has also substantial differences: it has often 3-foliate leaves, which are abaxially greenish grey or grey (not white), with a sharper serrature with long mucrons; short petiolulated central leaflets base; especially with young plants the lower leaflets are very small, like ears ( van de Beek & Widrlechner 2021). Nevertheless it was identified as R. ulmifolius and consequently conceived as a later synonym of R. inermis Pourr. ( Monasterio-Huelin & Weber 1996).

Willdenow’s type specimen is very poor, so that it was difficult to establish its identity ( van de Beek & Widrlechner 2021). Fortunately, recently, a young blackberry plant that corresponded precisely with Willdenow’s specimen was found in Veenendaal (NL) ( Fig. 1 ; for the type of Willdenow see: https://ww2.bgbm.org/Herbarium/specimen. cfm?Barcode=BW09891010). It grew under a high tree where birds used to rest, so that it may be supposed that is emerged from seeds in bird droppings. It was grown to adulthood in the garden so that the identity of a mature plant could be investigated. Plants bred from seeds kept the characteristics, also the lack of prickles. It appeared to be a taxon that is cultivated and sometimes escapes.

In contrast to the St. Francis blackberry, R. inermis sensu Willdenow remains unarmed in the next generation, so that it can be concluded that this feature belongs to the genome of the plant. Another important observation is that the plants are tetraploid ( Ferrer-Gallego & Van de Beek 2021), in contrast to the diploid R. ulmifolius . All together the distinctive characteristics of both taxa are so clear that it is better to provide R. inermis sensu Willdenow with a new name. We chose the epithet ‘ auritus ’, because of the very small lateral leaflets of especially young plants, such as Willdenow’s specimen, which are like ‘ears’ on the petiole. Because the young plant that Willdenow collected is not very instructive, an epitype is designated here. This is taken from the plant that was grown from the young plant that was found in Veenendaal.

Figures

FIGURE 1. Young blackberry plant of Rubus auritus A. Beek & P.P. Ferrer (Netherlands, Veenendaal, Petenbos 6, 52.00908N / 5.54351E).

FIGURE 2. Epitype of Rubus auritus A. Beek & P.P. Ferrer, collected in Netherlands, Veenendaal (Petenbos 6, 52.00908N / 5.54351E, 13 July 2023, A. Van de Beek 2023.04) and sent to herbarium B for preservation.

FIGURE 3. Primocane of Rubus auritus A. Beek & P.P. Ferrer; roundish to obtuse angular, diameter 5–10 mm, in the sun dark brown red, with dense very short stellate hairs.

FIGURE 4. Leaves of Rubus auritus A. Beek & P.P. Ferrer; 3-foliolate with lobate lateral leaflets, serrature irregular.

FIGURE 5. Peduncles of Rubus auritus A. Beek & P.P. Ferrer, slightly erect, densely short tomentose.

FIGURE 6. Petals of Rubus auritus A. Beek & P.P. Ferrer, pink to pinkish red, ovate or elliptical, sometimes slightly obovate length 11–15 mm, width 5–9 mm, and width-length index 0.45–0.66.