Description from Flora of China
Acer mirabile Handel-Mazzetti.
Trees small or shrubs, to 5 m tall, andromonoecious. Bark gray or blackish gray, rough. Branchlets reddish, slender, glabrous; winter buds brown, ellipsoid. Leaves deciduous; petiole 3-5 cm, slender, glabrous; leaf blade adaxially shiny, ovate, 7-9 × 6-8 cm, papery, abaxially glabrous or rufous pilose at primary vein axils, adaxially glabrous, base subcordate, margin serrulate with adpressed apiculate teeth, 3-lobed; middle lobe triangular-oblong, apex elongated caudate-acuminate; lateral lobes ovate, apex elongated caudate-acuminate. Inflorescence terminal on leafy branchlets, appearing after leaves develop, paniculate-racemose, 10-15-flowered, slender, with conspicuous bracts and small cincinni. Pedicel 1-1.5 cm, slender, glabrous. Flowers: sepals 5, reflexed, linear-oblong; petals 5, purple, linear-oblong; disk flat, glabrous; stamens 8, glabrous, inserted at middle of disk, much shorter in pistillate flowers; ovary purplish, rudimentary in staminate flowers. Fruit purplish yellow when mature; nutlets flat, oblong, ca. 8 × 4 mm; wing including nutlet 2.2-2.5 × ca. 1 cm, wings spreading obtusely. Fl. May, fr. Sep.
One of us (de Jong) notes that Acer wardii has similarities with A. sect. Macrantha, but the inflorescences (bracts, cincinni) and flowers (reflexed sepals and amphistaminal disk) are uncharacteristic of this section; thus, there are opinions that this species should be placed in a separate section, or at least as a separate series in A. sect. Macrantha. The DNA research of Tian et al. (Acta Bot. Sin. 44: 714-724. 2002) also supports the separate status of this species.
Alpine forests; 2400-3600 m. E Xizang, NW Yunnan [NE India, NE Myanmar].