Thorncroftia longiflora
Thorncroftia longiflora is an endangered species of Thorncroftia commonly called the longflower whistlesweet. It is endemic to South Africa′s Mpumalanga province.
Description
Thorncroftia longiflora is a semi-succulent, multi-stemmed suffrutex or small shrub, tall, arising from a thickened rootstock. Stems are sparsely branched, succulent at the base and brittle above, densely pubescent with glandular and non-glandular hairs.Leaves are opposite or occasionally whorled, Glossary of [leaf morphology#elliptic|elliptic] to obovate, long and wide, succulent and pubescent on both surfaces; the apex is obtuse, margins bear one to three small teeth near the upper third, and the petiole is long.
The inflorescence is a terminal panicle, sometimes with additional racemes from upper leaf axils, with single flowers in the axils of leaf-like bracts. The main axis is typically long. Flowers are borne on pedicels long, green at the base and darkening towards the tip. The calyx is long, green with a narrow maroon margin, densely glandular-pubescent; the upper lobe is broader than the others, and the remaining teeth are lanceolate.
The corolla is long and narrowly cylindrical, long, light lilac below and darker towards the lobes, with purple markings on the lateral lobes. The upper lobes are oblong, the lateral lobes narrowly oblong and sharply pointed, and the lower lobe is boat-shaped and becoming reflexed with age.
Stamens have light lilac filaments and dark purple anthers; pollen is orange-green. The lilac style elongates and becomes prominent after the stamens have recoiled.
T. longiflora flowers from February to July.
Distribution
When N.E. Brown named the genus in 1912, T. longiflora was its sole species, and, in time, its geographic distribution came to be understood to be the largest. However, subpopulations in KwaZulu-Natal and Eswatini were later described as separate species, and it is now believed to be confined to the immediate environs of the old Joe′s Luck Mine, on the Sheba Reef near Barberton, where it was first collected.Illegal mining threatens this much-circumscribed area of occurrence, and the authors of the 2025 revision of Thorncroftia recommend the species be reclassified from Rare to Critically Endangered in South [African National Biodiversity Institute|SANBI]′s Red [List of South African Plants].