Hydrangea jelskii
Andean sprawling hydrangea
Synonyms
- Hydrangea jelskii [ ]
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Introduction
Andean sprawling hydrangea is a functionally dioecious woody root-climber of humid Andean forests in Ecuador, Peru, and eastern Bolivia. Unlike the umbel-like flowering structures characteristic of many members of Section Cornidia, Hydrangea jelskii generally produces a conspicuously branched, thyrse-like inflorescence. Its flowers are white and enlarged marginal flowers are absent. Stellate hairs occur on the lower leaf surface and the inflorescence branches, providing an important contrast with the essentially glabrous foliage of the closely associated H. tarapotensis (McClintock 1957; Granados Mendoza et al. 2021; Sutton 2025).
The AAU herbarium record for J. Schunke 5856, collected in the Lamas area of Peru on 6 April 1973 and identified as H. jelskii, describes a 12–14 m liana tightly appressed to tree trunks in tall forest at 900 m, with bright yellow-green flowers (Aarhus University Herbarium n.d.). This single collection should not define an ecological envelope for the species. Molecular evidence indicates that material presently called H. jelskii may encompass more than one biological lineage (Granados Mendoza et al. 2021).
The nomenclatural history begins with Constantin Jelski's nineteenth-century Peruvian collections. Ignacy Szyszylowicz described H. jelskii from that material in 1894; a second Hydrangea jelskii, published by Zahlbruckner at effectively the same time, is a later illegitimate homonym and is retained as a nomenclatural synonym rather than evidence for a second taxon. POWO currently accepts the Szyszylowicz species across Ecuador, Peru, and eastern Bolivia (Royal Botanic Gardens, Kew 2026).
Its modern evolutionary interpretation is far more complicated. In the two-low-copy-nuclear-gene phylogeny of Granados Mendoza et al. (2021), H. jelskii belongs to strongly supported Clade F, but its sampled individuals do not form a single branch. Instead, H. jelskii accessions are distributed among several portions of a shallow assemblage also containing H. mathewsii, the strongly monophyletic H. tarapotensis, and undescribed entities provisionally called Hydrangea sp. 3 and sp. 4. Some H. jelskii individuals are paired directly with H. mathewsii, while others occur elsewhere in the clade.
That result is not good evidence for simply merging H. jelskii and H. mathewsii. Both remain morphologically recognizable, and the molecular dataset contains only two low-copy nuclear loci in a lineage where incomplete lineage sorting and gene exchange are recurrent. A more interesting—and biologically plausible—interpretation is that the traditional jelskii–mathewsii taxonomy is seeing part of a young Andean radiation whose full structure has not yet been resolved. Some currently named populations may be correctly circumscribed, others may cross present species boundaries genetically, and the unnamed sp. 3 and sp. 4 entities indicate that additional diversity is already visible to specialists (Granados Mendoza et al. 2021).
The reproductive ecology of H. jelskii also provides one of the few direct observations of flower visitors anywhere in tropical Cornidia. During field work near Chachapoyas, Peru, Granados Mendoza and colleagues observed numerous fungus gnats of the genus Sciara visiting floral nectaries. The researchers could not determine whether the insects were acting as effective pollinators, nor whether they were attracted principally by nectar or by other flies, so the observation should not be upgraded to a demonstrated pollination syndrome. Nevertheless, it provides a rare window into the largely unknown reproductive biology of these functionally dioecious canopy lianas (Granados Mendoza et al. 2021).
Horticultural and Agricultural Uses
There is no established horticultural or agricultural tradition for H. jelskii. Its large climbing habit, white branched inflorescences, and adaptation to humid Andean forests could make it an interesting botanical-collection plant, but there is too little verified cultivation experience to offer species-specific garden recommendations.
Living collections would have considerably greater scientific value. Provenance-documented plants from Ecuador, northern Peru, central Peru, and Bolivia could provide observations of architecture, flowering phenology, functional sex, and pubescence while simultaneously supplying the population-level material needed to clarify the jelskii–mathewsii complex.
The fungus-gnat observation also suggests a useful research opportunity for cultivated material. Flowering male and female accessions maintained together could permit direct observation of floral visitors and experimental testing of pollen transfer, moving Cornidia reproductive biology beyond the scattered field observations presently available.
Conservation Concerns
No formal global IUCN Red List assessment for narrowly interpreted H. jelskii was located in the sources reviewed. A distribution spanning three Andean countries might suggest security, but the molecular evidence makes range size unusually difficult to interpret. If material presently identified as H. jelskii contains several lineages, the apparent Ecuador-to-Bolivia distribution could conceal much smaller individual ranges (Royal Botanic Gardens, Kew 2026).
This is therefore a case where taxonomic research is directly relevant to conservation. Population-scale sampling should deliberately cross geographic boundaries and include H. mathewsii, sp. 3, and sp. 4 rather than simply accumulating more individuals already labelled H. jelskii. Until that work is done, ex situ collections should preserve precise provenance rather than treating accessions from different parts of the Andes as biologically interchangeable.
Additional Information
- Plants of the World Online — Hydrangea jelskii (opens in a new tab): provides current nomenclature, the Ecuador–Peru–Bolivia backbone distribution, and the illegitimate later homonym.
- Trees and Shrubs Online — Section Cornidia (opens in a new tab): summarizes the species' branched inflorescences, indumentum, and unresolved species-complex status.
- iNaturalist observations — Hydrangea jelskii (opens in a new tab): can be useful for finding modern photographic records, but identifications should be interpreted cautiously while the complex remains unresolved.
References and Further Reading
Aarhus University Herbarium (AAU) (n.d.) Hydrangea jelskii: Specimen J. Schunke 5856, collected 6 April 1973. AAU Herbarium Database. https://www.aubot.dk/show_entry.php?CatalogNumber=J.Schunke5856 (opens in a new tab) (accessed 9 October 2026).
Granados Mendoza C, Martínez Salas EM, Goetghebeur P, Wanke S, Samain M-S (2021) Molecular phylogeny, character evolution, and biogeography of Hydrangea section Cornidia, Hydrangeaceae. Frontiers in Plant Science 12: 661522. https://doi.org/10.3389/fpls.2021.661522 (opens in a new tab)
McClintock E (1957) A monograph of the genus Hydrangea. Proceedings of the California Academy of Sciences, Fourth Series 29(5): 147–256. https://www.biodiversitylibrary.org/part/51707 (opens in a new tab) https://doi.org/10.5281/zenodo.15905786 (opens in a new tab)
Sutton J (2025) Hydrangea species of Section Cornidia. Trees and Shrubs Online. International Dendrology Society. https://www.treesandshrubsonline.org/articles/hydrangea/hydrangea-species-of-section-cornidia/ (opens in a new tab)
Szyszylowicz I (1894) Diagnoses plantarum novarum a cl. d. Const. Jelski in Peruvia lectarum, pars prima. Sumptibus Academiae litterarum, Cracovie. https://openlibrary.org/books/OL57326397M (opens in a new tab)