Oenothera fallax Renner, Z. Indukt.
Creators: name: Woźniak-Chodacka, Monika
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Onagraceae
Oenothera
Oenothera fallax

description: Oenothera fallax Renner, Z. Indukt. Abstammungs- Vererbungsl. 18(3‒4): 176. 1917.
Type:— GERMANY. Based on an artificial hybrid between a strain of O. glazioviana [‘ O. lamarckiana Heribert-Nielson’] and a strain of O. biennis [O. biennis München from the Botanical Garden Münich]. Lectotype (designated here):—Figure 20 in Renner 1917: 177. Epitype (designated here):— POLAND. Dolnośląskie: Wrocław, in ruins along Podwale Street, near Oławska Street, 16 July 1962, K. Rostański s.n., 2 sheets (WRSL!, barcodes 4009786 and 4009787). Figs. 1‒2.
Morphology: —Stem over 100 cm tall, with branches, green or somewhat reddened, distinctly red-punctulated, with numerous long stiff hairs with bulbous red bases and shorter arcuate hairs. Leaves elliptic to ovato-lanceolate, with white or reddish midrib, denticulate, the lower ones crinkled (Fig. 3). Rhachis green, red punctulated (Fig. 4), reddened at apex with numerous glandular hairs and stiff hairs with red bulbous bases. Buds red-striped (Fig. 5), covered with glandular and stiff hairs; sepal tips 2‒4 mm, appressed below, divergent to appressed above. Hypanthia 30‒40 mm long. Petals yellow, obcordate, relatively large, 20‒30(35)× 22‒34(38) mm. Anthers and stigma-lobes 3‒10 mm long; stigma lobes spreading between anthers. Capsules green, red-striped and red-punctulated when young with numerous glandular hairs; teeth short, about 2 mm long, obtuse to somewhat emarginate.
Seeds of the colour between dark brown and black; 1.1‒2.2 mm long, 0.4‒1.7 mm thick, 0.4‒1.5 mm high (Rostański et al. 1989, 2010).
Similar taxa: — Oenothera fallax most closely resembles one of its parent— O. glazioviana, mostly by its large flowers, red-striped flower buds and red-coloured papillae covering the plant. However, the flowers of O. fallax are much smaller, with a relatively short style and stamens hidden among the anthers. Moreover, O. fallax is similar to O. fallacoides Soldano & Rostański (Soldano 1983: 128), which, according to authors of the name, differs largely by red-coloured external surface of the bracts (Soldano 1983).
Origin: —Arisen in Europe, as a hybrid resulting from a cross O. glazioviana × O. biennis (Renner 1917, Rostański 1965).
Note: —In the articles concerning genetics of Oenothera, especially the early ones (e.g. de Vries 1901 –03, MacDougal et al. 1907, Priestley 1985), O. glazioviana was usually given as O. erythrosepala Borbás (1903: 245) or O. lamarckiana auct. genet. non Seringe ex De Candolle (1828: 47).
Genetic features: —Haploid genome combination: velans [from O. glazioviana]— rubens [from O. biennis] (Rostański 1965); 2n=14 (Przywara & Rostański 1980), during the first meiotic division chromosome form a ring of 12 and one bivalent (Dietrich et al. 1997).
Biology: —Biennial, true-breeding,unlike the hybrid resulting from a reciprocal cross[O. biennis × O. glazioviana]; autogamous, permanent translocation hybrid (PTH) (Rostański & Karlsson 2010).
Distribution: —Grown for ornament since the middle of 19 th century, often with O. glazioviana, also spontaneously formed in nature (Rostański & Karlsson 2010). Formally the species was described from Germany (Renner 1917), later it was observed in Wrocław, Western Poland (Rostański 1965). Currently, the species is widespread in Europe, especially in North, Central and East part of the continent (Rostański et al. 2010), although single localities were also reported from Asia as far as Japan (GBIF, occurrence not confirmed by a specialist).
Habitats: —As most evening primroses, O. fallax is usually found in disturbed habitats, roadsides, ruderal grasslands and wastelands (Rostański & Karlsson 2010).
Flowering time: —From June to October (Rostański 1963).
Hybrids: —According to Rostański (1982), Oenothera fallax hybridises with O. biennis and O. glazioviana (formally those are backcrosses), as well as with O. cambrica Rostański (1977: 285) in both directions. Moreover, hybrid offspring originated via crossing with O. victorinii Gates & Catcheside (in Gates 1933: 182) as male parent was described as a hybridigenous species— O. moravica V. Jehlík & Rostański (1995: 440), whereas O. × hassica Rostański & Schnedler nom. prov. (1991) probably resulted from a cross O. fallax × O. pycnocarpa. Recently, hybrids of O. fallax with O. deflexa Gates (1936: 332) and O. casimiri Rostański in Rostański et al. (2004: 21) were also reported (Hassler 2019).
Taxonomic status: —According to the representatives of the American school of taxonomy, O. fallax is treated as a hybrid with no formal rank (Dietrich et al. 1997). In contrast, European taxonomists consider O. fallax as one of many well-established, hybrid-originated species (Hudziok 1968, Soldano 1983, Jehlík 1993, Woźniak 2009, Rostański et al. 2010). Based on its morphology, the species was initially assigned to the section Oenothera (Rostański 1965), which later was transformed into the series Oenothera (Rostański 1985).
Variability: —Two morphological variants differing by the colour of the midribs were recognized by Rostański, however only one name (O. fallax f. rubrinervis) was validly published. Moreover, in the literature one may find two provisional names referring to intraspecific variability of the considered species, O. fallax var. rugosa (Hassler 2019) and O. fallax f. brevihypanthialis Rostański (Woźniak 2009, Hassler 2019).
description: Published as part of Woźniak-Chodacka, Monika, 2023, Lectotypification, epitypification and taxonomic notes on Oenothera fallax (Onagraceae), pp. 283-292 in Phytotaxa 612 (3) on pages 285-289, DOI: 10.11646/phytotaxa.612.3.4, http://zenodo.org/record/8323610