Description from Flora of China
Lagerstroemia speciosa (Linnaeus) Persoon var. intermedia (Koehne) Furtado & Montien.
Trees, 6-12 m tall. Branchlets terete, glabrous. Petiole 1.2-1.5 cm; leaf blade elliptic or oblong-elliptic, rarely elliptic-obovate, 7-18 × 4-8 cm, papery to thinly leathery, abaxially paler and conspicuously reticulate, lateral veins 10 or 11 pairs, base acute to attenuate, apex shortly acuminate. Panicles 10-15 cm, glabrous or puberulous. Floral tube 6-merous, 1.2-1.5 cm, smooth walled or with 12 shallow, broad ribs, densely yellow-brown puberulous; sepals narrowly deltate, 5.5-8 mm, ca. 1/2 as long as floral tube, adaxially glabrous; annulus absent; epicalyx segments absent or minute. Petals purple to bluish purple when dry, ovate, 2-2.5 cm including claw 5-7 mm. Stamens 75 to ca. 130, in 2 or 3 whorls, monomorphic. Ovary glabrous. Capsules oblong, 2.5-3.5 × ca. 2 cm, 6-valved. Seeds yellowish brown, ca. 10 mm including wing. Fl. May-Jun, fr. Oct-Dec.
This species is very similar to the widespread and commonly cultivated Lagerstroemia speciosa (Linnaeus) Persoon. The lectotype of L. intermedia differs in having slightly smaller, non-apiculate buds and smaller flowers that are very shallowly ribbed or smooth walled. In L. speciosa, the buds are typically apiculate and the floral tubes are more deeply and conspicuously ribbed, but it is uncertain if there is a continuum from shallow to deep ribbing. If there is a continuum, then L. intermedia is better considered a variety of L. speciosa. Epicalyx segments described by Koehne in the protologue of L. intermedia that might be a useful character are, in fact, not present on the lectotype.
Lagerstroemia intermedia is very local and of some conservation concern.
Scrub forests, hillsides, roadsides; 800-1500 m. SW Yunnan [Myanmar].