Geum coccineum x Geum rivale

Taxonomy: Fam. Rosaceae// Genus: Geum// Hybrid: Geum coccineum x Geum rivale. Parental species: Geum coccineum Sibth. & Sm. and Geum rivale L.

The hybrid from Osogovo shows similar morphological characteristics compared to the data provided by Gajewski (1950). A population of over a hundred specimens discovered in 2023 showed more or less typical F1 characteristics, while the parental species in proximity looked quite pure. Clear visual signs of introgression were not observed.

The following morphological characteristics were observed on the population from Osogovo (Ponikva region): In general habit, the hybrid is intermediate between the two parents. Plant height tends towards G. rivale. Anthocyanin is present as in G. rivale. Stem indumentum is intermediate with both simple and glandular hairs. The peduncles are pendent in bud (as in G. rivale) and slightly pendent to semi – erect (intermediate) in flower. Petals and sepals are erect at beginning of flowering as in G. rivale; petals become semi-erect, while sepals semi-erect to almost horizontal in fully developed flowers. The hybrid differs from both parents in having bright yellow petals, a characteristic not typical for either of the parental species (cream to pink in G. rivale and orange-red in G. coccineum). Petals are more or less emarginate, tending towards G. rivale. Claw of petal short – 1 to less than 2 mm. Carpophore is absent in flower and very weakly developed in fruit (tending towards G. coccineum). Rostrum of fruit is c. 3 times as long as body, tending towards G. coccineum as opposed to G. rivale which has longer rostrum – up to 5 times as long as fruit. Hairiness of rostrum is intermediate (hairy in G. rivale, glabrous in G. coccineum, moderately hairy in the lower part in the hybrid). Leaf shape varies even in the same plant, from intermediate to tending towards either of the parental species.

Distribution: The occurrence of the hybrid in North Macedonia was recorded by Micevski (1998). According to Gajewski (1950), the range of the parental species overlaps in the Balkan Peninsula and Asia Minor, however they rarely meet together and in the line of contact they sporadically form natural hybrid populations, stating differences in altitudinal distribution, time of flowering and pollination factors. In the Osogovo region Geum rivale is found at higher altitudes – at c. 1500 m above, in European beech forests, wet grasslands and alongside streams, therefore partially sharing the same habitat as Geum coccineum. In this region both species flower simultaneously during May – June, therefore allowing hybridization to occur.

Habitat: In the Osogovo region G. coccineum x G. rivale is found in open wet habitats – along streams at c. 1500 m – 1900 m altitude, where both of the parental species occur. Recorded in Ponikva and the region of “Carev vrv” peak.

Lifeform: Perennial plant. Hemicryptophyte according to the Raunkiaer system.

Flowering period: Late spring to early summer (MAY, JUN).

Parental species *Geum coccineum* and *Geum rivale* growing next to each other on the edge of a mountain stream. Osogovo – Ponikva, 04.06.2023. Photo by Trajche Dimitrovski.

*Geum coccineum* x *Geum rivale* – habit. Osogovo – Ponikva, 18.06.2023. Photo by Trajche Dimitrovski.

Locality: “Carev vrv” peak.

Habitat of *Geum coccineum* x *Geum rivale* in the region of “Carev vrv” peak- springs of “Bela” River, 24.05.2024. Photo by Trajche Dimitrovski.

References:

Gajewski, W. (1950). The inheritance of specific traits in the hybrid Geum coccineum x rivale. Acta Societatis Botanicorum Polonia Vol. 20, No. 2, pp. 455 – 476. DOI: https://doi.org/10.5586/asbp.1950.022 [Accessed 19.09.2023].

Micevski, K. 1998. Geum L., The Flora of the Republic of Macedonia. Vol. I, Book 4. Skopje: Macedonian Academy of Sciences and Arts, pp. 927–933.

Last update: 24.05.2024.

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