Robinia × longiloba Ashe — Ashe’s locust

Introduction

Ashe’s locust is a deciduous woody shrub or small tree representing the hybrid combination Robinia hispida × R. viscosa. It is native to the southeastern United States and is presently recorded from North Carolina and South Carolina. Plants of the World Online and regional floristic treatments continue to recognize the nothospecies as a distinct hybrid entity. (Isely & Peabody 1984; Royal Botanic Gardens, Kew 2026)

The hybrid joins two of the pink-flowered southeastern locust lineages, both of which possess glandular or bristly indumentum. This makes individual plants more difficult to recognize at a glance than hybrids involving white-flowered R. pseudoacacia. Identification must therefore consider combinations of stem armature, gland type, pubescence, foliage, flowers, and fruit rather than relying on flower color alone.

Tree TSAR retains the conventional parentage R. hispida × R. viscosa. This point matters because R. hartwigii also hybridizes with both R. hispida and R. viscosa. Regional treatments have recorded those combinations separately, and there is no reason to use × longiloba as a catch-all name for every intermediate involving stalked-gland locusts. (Weakley & Southeastern Flora Team 2025)

Robinia × ashei Schallert is treated as a synonym of × longiloba. (Royal Botanic Gardens, Kew 2026)

Horticultural and Agricultural Uses

The chief practical value of Ashe’s locust is botanical rather than commercial: recognizing the hybrid prevents naturally intermediate plants from being forced into either parental species and therefore improves the interpretation of field, herbarium, and conservation records.

Plants originating from natural southeastern hybrid zones may also be of interest to specialist collections studying Robinia variation and hybridization. Provenance should be retained carefully because an undocumented cultivated intermediate has much less value for understanding natural gene flow.

Conservation Concerns

Ashe’s locust is not known to require separate conservation management, but well-documented natural occurrences are valuable evidence of gene flow between R. hispida and R. viscosa. Protecting intact parental populations and their natural contact zones preserves the evolutionary setting in which the hybrid occurs.

Additional Information

Plants of the World Online (opens in a new tab): Accepted account for Robinia × longiloba, including distribution, parentage, and × ashei synonymy.
World Flora Online (opens in a new tab): Nomenclatural record for R. longiloba.
Integrated Taxonomic Information System (opens in a new tab): Accepted North American record for × longiloba.

References and Further Reading

Integrated Taxonomic Information System (2026) Robinia × longiloba Ashe.

Isely D, Peabody FJ (1984) Robinia (Leguminosae: Papilionoideae). Castanea 49(4): 187-202.

Royal Botanic Gardens, Kew (2026) Robinia × longiloba Ashe. Plants of the World Online.

Weakley AS, Southeastern Flora Team (2025) Flora of the Southeastern United States Web App. University of North Carolina Herbarium, North Carolina Botanical Garden, Chapel Hill.

World Flora Online (2026) Robinia longiloba Ashe. World Flora Online.