Description from Flora of China
Piper blandum Jacquin, Collectanea 3: 211. 1789; Peperomia arabica Decaisne ex Miquel var. floribunda Miquel; P. blanda var. floribunda (Miquel) Hüber; P. dindygulensis Miquel; P. esquirolii H. Léveillé; P. fauriei C. de Candolle; P. formosana C. de Candolle; P. japonica Makino; P. laticaulis C. de Candolle; P. leptostachya Hooker & Arnott; P. leptostachya f. cambodiana C. de Candolle; P. leptostachya var. cambodiana (C. de Candolle) Merrill; P. sui Lin & Lu.
Herbs perennial, usually terrestrial, (10-)20-45(-50) cm high, all parts pubescent. Stolons present, slender, leafless. Stems often very fleshy, often reddish. Petiole (0.5-)1-1.5 cm; leaf blades elliptic-obovate, those at base of stem sometimes suborbicular, abaxially often reddish, 2-4(-6.5) × 1-2(-4) cm, ± membranous when dried, glandular, both surfaces pubescent, base tapered to cuneate, apex rounded to subacute; veins 3(-5). Spikes terminal and from axils of apical leaves, sometimes fascicled, (3.5-)5-8(-12) cm, flowers lax; peduncle 0.5-1.5(-2) cm; rachis 2.5-10 cm × (0.5-)1-2 mm; bracts ± orbicular, ca. 0.8 mm wide, gland dotted. Filaments short, thecae rounded-"D"-shaped. Ovary obovoid, apex obtuse to emarginate. Nutlet sometimes borne on shortly conical false pedicel when fully ripe, globose to broadly ellipsoid, 0.5-0.8(-1.2) mm, obscurely papillate. Fl. Apr-Dec.
A very wide view has been taken of this taxon, which is treated as a pantropical species. The extremes are certainly very distinct: robust, green plants with large whorls of blunt tipped leaves ("Peperomia japonica"), contrasting with more slender plants, often with reddish stems and abaxial leaf surfaces, and with pairs of acutely tipped leaves ("P. dindygulensis"), but these are connected through intermediates, and it does not seem practicable to separate taxa. A possible exception is the recently described P. sui, from Taiwan, which is very clearly differentiated from other collections from that island (which mostly fall comfortably within P. japonica sensu stricto) by the minutely papillate abaxial leaf epidermis. This feature is very difficult to see in herbarium material and needs investigating more widely. The "pseudopedicels" (minute, domed swellings of the rachis that raise up the mature fruit), which are supposed to provide a distinction between P. blanda and P. leptostachya (present in the former, absent in the latter), occur very irregularly throughout the range of this species and are probably of uncertain significance.
Forests, shady, wet rock crevices; 100-1900 m. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Taiwan, Yunnan [Bangladesh, Cambodia, India, Japan, Malaysia, Myanmar, Sri Lanka, Thailand, N Vietnam; Africa, SW Asia, South America]