Decne.
Description
Allardia glabra is a high-alpine composite of the Himalaya and central Asia, distributed across Nepal, India, China, Pakistan, Tajikistan, Bhutan, Afghanistan and Kazakhstan, with GBIF documenting about 327 occurrences. It is a plant of the uppermost alpine and subnival zones, growing on screes, moraines, gravelly flats and stony slopes at very high elevations, commonly between about 4000 and 5500 m. The photographed material from Yume Samdong in northern Sikkim at 4700 m, flowering in August, is typical of its extreme habitat, where it forms low cushions or mats on bare, frost-disturbed ground near the limit of vascular plant life, taking advantage of the short, intense growing season of the high summer.
It is a dwarf, cushion- or mat-forming perennial arising from a branched, often stout caudex clothed in the persistent remains of old leaves. The leaves are small, crowded, spathulate to obovate and entire or shallowly lobed at the tip, and, as the epithet glabra indicates, relatively glabrous compared with the woolly indumentum of related species. The flower heads are solitary, sessile or shortly stalked, nestled among the foliage, and radiate, with an involucre of imbricate, often dark-margined bracts. The pistillate ray florets are pink to lilac or whitish, surrounding numerous yellow tubular disc florets. The fruit is a small, ribbed cypsela crowned by a short pappus.
Allardia is a small genus of about half a dozen species centred on the high mountains of central Asia and the Himalaya, long included within Waldheimia, under which name (Waldheimia glabra) this taxon is frequently encountered. Its cushion habit, reduced glabrous leaves and ground-hugging capitula are classic adaptations to cold, wind-exposed, high-radiation subnival environments. As a specialist of the highest vegetated ground it is of biogeographic interest and potentially sensitive to upward shifts of the climatic snowline, though its remoteness affords protection.
Author: Decne. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Pakistan, Annotated Checklist of the Flowering Plants of Nepal, Podlech and Asteraceae monographic treatments of Allardia (Waldheimia)