An evergreen shrub or small tree up to 25 ft high; young shoots reddish, woolly at first. Leaves oblong to narrowly obovate, rounded to abruptly tapered at both ends, mucronate, 2 to 4 in. long, 1 to 11⁄2 in. wide; dark green above, glaucous-white beneath, glabrous except on the midrib beneath; stalk 1⁄3 to 3⁄4 in. long, reddish and downy when young. Flowers six to twelve in a truss 3 to 4 in. wide, opening in March or April; pedicels about 1⁄2 in. long, downy. Calyx membranous, varying in size and very irregular, with five unequal rounded lobes. Corolla rich crimson, tubular-bell-shaped, 11⁄2 to 13⁄4 in. long, not so much wide, with five rounded, notched lobes. Stamens ten, white, glabrous, 3⁄4 to 11⁄4 in. long; anthers very dark brown. Ovary felted; style slightly overtopping the stamens, glabrous except just above the ovary. Bot. Mag., t. 8727. (s. and ss. Neriiflorum)
Native of mid-Yunnan westward through upper Burma to the eastern Himalaya, where it reaches almost as far as Bhutan. It was discovered by Père Delavay in the Tali range, Yunnan, and introduced from the same area by Forrest in 1910 (F.6780). Here, at least on the eastern flank of the range, where there is little forest, it makes a shrub 2 to 8 ft high, occurring in open pinewoods, shaded gullies, or rocky pastures, at 10,000 to 12,000 ft. The seeds of the original introduction were taken from low-growing plants and produced dense, very free-flowering bushes, but these eventually grew much taller than the parental wild plants, e.g., to 10 ft high at Werrington Park in Cornwall.
Plants of Tali provenance are rare in gardens. Mostly, the cultivated stock derives from seeds collected farther west, where R. neriiflorum, though often a dwarf shrub at subalpine elevations, is more commonly taller growing, and sometimes a small tree. These plants, once usually known by the synonymous name R. euchaites, make erect, rather lax shrubs up to 15 ft high. The flowers are usually of the purest crimson-scarlet and borne in great profusion in late March, April, or May. Out of flower, the species is easily recognisable by its neat, oblongish leaves, glaucous white beneath. It is perfectly hardy in light woodland south of London, and received an Award of Merit when shown from Bodnant on March 26, 1929.
A form of R. neriiflorum with leaves tapered at the apex, a fewer-flowered inflorescence, and smaller calyx, was introduced by Farrer and Cox in 1919 from the pass above Hpimaw, Burma, on the Salween-Nmai Hka (Irrawaddy) divide. It was given specific status as R. phoenicodum Balf. f. & Farrer, but should probably be regarded as part of the normal variation of the species. It is figured in Bot. Mag., t. 9521.
R. phaedropum Balf. f. & Farrer – This differs from R. neriiflorum in having the ovary glandular as well as hairy. Also, at least in the type-plants, the colour of the flowers ranges from straw-yellow to salmon rose and light scarlet, but such aberrations in colour are common in the Neriiflorum series. This species, perhaps no more than a glandular state of R. neriiflorum, was discovered by Farrer on the Nmai Hka (Irrawaddy)-Salween divide above Nyitadi in 1920. Plants found by Ludlow and Sherriff in S. Tibet and Bhutan were referred to it by Dr Cowan.