Start a consultation

Support Tree TSAR: Sponsorship Opportunities

Hydrangea trianae Briq.

Leatherleaf sprawling hydrangea

Synonyms
  • Hydrangea lehmannii Engl.
  • Hydrangea platyphylla Briq.
Suggest a Correction

Introduction

Leatherleaf sprawling hydrangea is one of the geographically most successful members of the revised Andean Cornidia complex. It ranges from Colombia through Ecuador into Peru and occurs across an extraordinary elevational span, from about 400 to 3,680 m. Although fundamentally a cloud-forest liana, it also persists in forest remnants and some disturbed or late-secondary woodland and has been collected in reproductive condition throughout the year (Samain et al. 2021).

Its leaves provide one of the strongest vegetative identities in the entire complex. They are large—roughly 15–29 cm long—conspicuously coriaceous, spoon-shaped, and obovate to elliptic. Beneath, the primary veins stand prominently above the surface while secondary and tertiary veins link them into a conspicuous reticulate network. White stellate hairs cover the lower surface, and the apical portions of flowering shoots bear dense, erect whitish to yellowish hairs. In combination, the leathery texture, netted venation, and pale indumentum make H. trianae recognizable even when flowers are unavailable (Samain et al. 2021; Sutton 2025).

The species also provides an elegant example of how functional dioecy can distort traditional taxonomy. Briquet described H. trianae and H. platyphylla separately using collections of opposite functional sex. Characters involving cyme dimensions, enlarged marginal flowers, and styles appeared different, but modern re-examination showed that several of those distinctions reflected male versus female floral morphology rather than separate species. Hydrangea platyphylla is therefore synonymized here, together with H. lehmannii (Samain et al. 2021).

Molecular evidence complicates rather than undermines this recognizable morphology. Multiple H. trianae accessions occur within Clade H together with H. goudotii and plants identified as H. aff. trianae. Some H. trianae samples cluster strongly, but the species is not isolated as one simple exclusive branch in the two-gene tree. This suggests that the very broad Colombia–Ecuador–Peru concept may contain shallow geographic structure, historical introgression, incompletely sorted variation, or possibly additional cryptic lineages (Granados Mendoza et al. 2021).

For the moment, morphology supports retaining H. trianae as a widespread species rather than fragmenting it on limited gene-tree evidence. The next decisive step is range-wide population genomics, particularly involving H. goudotii and the morphologically intermediate H. aff. trianae material. Tree TSAR accepts the species while preserving that review trigger.

Horticultural and Agricultural Uses

There is no established commercial horticulture for H. trianae, but its enormous altitudinal range makes it one of the more interesting Andean Cornidia for experimental cultivation. Provenances from 400 m and from well above 3,000 m may differ greatly in climatic tolerance, and an unprovenanced plant could give a misleading impression of what the species as a whole can endure.

Its large, exceptionally leathery leaves provide ornamental interest even outside flowering, while the dense pale pubescence of the young flowering growth gives it a distinct texture. In botanical collections it would also serve as an excellent living demonstration of the difference between vegetative diagnostic characters and the sexual characters that historically contributed to unnecessary splitting.

Conservation Concerns

A broad distribution does not translate into broad security. Samain et al. (2021) estimated an extent of occurrence approaching 726,300 km² but an area of occupancy of only about 372 km², and applied Endangered under criterion B2ab(iii) because of extensive destruction and fragmentation of suitable forest. This remains a specialist-applied assessment rather than a formal IUCN listing.

The species' ability to persist in secondary or disturbed forest may provide some resilience, but it should not be equated with independence from forest habitat. Mature host trees, humidity, and connectivity remain important for a large functionally dioecious liana.

Its broad range also creates an underappreciated conservation problem: preserving a few cultivated accessions cannot adequately sample a lineage spanning Colombia, Ecuador, and Peru and nearly 3,300 m of elevation. Provenance representation should therefore be treated as a major goal in ex situ collections.

Additional Information

References and Further Reading

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

Samain M-S, Granados Mendoza C, Martínez Salas EM (2021) On Hydrangea peruviana, an endangered species from Ecuador, and Hydrangea oerstedii, very common in Costa Rica and Panama, and seven threatened Central and South American hydrangeas, which have been confounded with these. PhytoKeys 171: 91–153. https://doi.org/10.3897/phytokeys.171.56351

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/