Scientific name: Sorbus x houstoniae

Status: IUCN – Critically Endangered

Flowering time: Creamy white flowers May. Orangey-red berries from late September – October.

Description: Small tree growing up to 4 metres tall with similar, but wider leaves than the Bristol whitebeam and orangey-red fruits. Hybrid – only one tree known to exist!

Social history: First discovered by Bristol botanist, Libby Houston, in 2004.

Taxonomy: Rosaceae (or rose) family. Hybrid between Sorbus aria (common whitebeam) and Sorbus bristoliensis (Bristol whitebeam).

Global and national distribution: Endemic to the Avon Gorge. The Avon Gorge is particularly famous for its whitebeams. Including Houston’s whitebeam there are seven kinds of whitebeam endemic to the Avon Gorge. The others are Bristol, Wilmott’s, Observatory, Avon, Leigh Woods and Robertson’s whitebeams.

Threats: Overgrowth of ivy.