Pterygiella cylindrica is a perennial root-hemiparasitic herb endemic to the grassy mountain slopes and dry valleys of southwestern China, specifically in Yunnan and Sichuan provinces. Unlike all other members of its genus, which feature square stems bordered by leafy wings, this species grows upright with completely round, unwinged stems—a trait directly reflected in its Latin specific epithet cylindrica.
Classified within the broomrape family (Orobanchaceae, historically placed in Scrophulariaceae), the species was first scientifically described in 1963 by the Chinese botanist Pu-Chiu Tsoong in the journal Acta Phytotaxonomica Sinica. Botanists recognize two infraspecific taxa within this rare mountain plant: the nominate form and the woody-based subspecies Pterygiella cylindrica subsp. suffruticosa.
Pterygiella cylindrica is an erect, somewhat rigid herb reaching 20 to 40 centimeters in height, often drying dark brown or black in herbarium specimens due to the presence of iridoid glycosides in its tissues. The plant is covered in a dense vestiture of microscopic, glandular and non-glandular hairs that give the stem and foliage a slightly rough, velvety texture.
The defining structural feature of the species is its terete (cylindrical) stem, which lacks the longitudinal decurrent wings found in its closest relatives. Several stems often arise from a woody rootstock, branching sparingly near the middle or upper portion.
Flowers are arranged in terminal, leafy racemes where each flower sits in the axil of a leaf-like bract on a very short pedicel. The floral architecture is adapted for insect pollination in montane habitats.
Late summer to autumn (July to October)
The generic name Pterygiella literally translates to "little wing," referring to the four papery strips of tissue that run down the stems of almost every species in the group. Yet Pterygiella cylindrica breaks this rule with a completely smooth, cylindrical stem, representing an evolutionary link between winged Pterygiella species and neighboring genera in the tribe Pterygielleae.
Growing at elevations between 1,800 and 2,800 meters in the Hengduan Mountains and dry-warm river valleys of Yunnan and Sichuan, the plant faces seasonal drought, intense mountain winds, and nutrient-poor rocky soils. Its survival relies on a finely tuned coordination between above-ground stem geometry and an underground parasitic network.
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