Benth.
Description
Buddleja macrostachya is a widespread Sino-Himalayan and Indochinese shrub, recorded from China, India, Vietnam, Myanmar, Thailand, Bhutan, Bangladesh and Nepal, with over 400 documented occurrences spanning the eastern Himalaya into mainland Southeast Asia. It is a plant of open hillsides, forest margins, thickets, roadsides and disturbed slopes in subtropical to temperate zones, generally between about 1000 and 3200 m. The illustrated plants from Jakar in central Bhutan at 2900 and 3100 m, flowering in October, demonstrate its autumn flowering at the upper end of its altitudinal range, where it forms conspicuous shrubs in sunny, often disturbed montane habitats.
It is a large shrub with quadrangular, densely stellate-tomentose young branches. The leaves are opposite, lanceolate to narrowly elliptic, long-acuminate, with a crenate-serrate margin, dark green and rugose above and grey- to fawn-tomentose beneath, the bases joined by an interpetiolar stipular line. The inflorescence is a long, narrow, interrupted spike-like thyrse (reflected in the epithet macrostachya, large-spiked) of many congested cymose clusters. Individual flowers are small, with a four-lobed campanulate corolla that is pale lilac to pink or purplish with an orange throat, and four included stamens. The fruit is a small, septicidal, two-valved capsule releasing numerous minute seeds.
Although listed here under Scrophulariaceae following the broad APG placement of Buddleja, the genus is also frequently treated in its own family Buddlejaceae; B. macrostachya Benth. is the accepted name. The nectar-rich, fragrant inflorescences attract butterflies, moths and other long-tongued insects, while the light, winged seeds are wind-dispersed. As a vigorous coloniser of open and disturbed ground it is common and widespread, and of least conservation concern.
Author: Benth. · Sources: POWO (Kew), GBIF, Flora of China Vol. 15, Flora of Bhutan Vol. 2, Flora of Nepal, Leeuwenberg The Loganiaceae of Africa and Buddleja revisions (monograph)