Table 2.

Morphological comparison of key characteristics in H.stenopterum, H.incurvatum, H.lushuiensis, and the most widespread H.benghalensis.

Character	stenopterum	H.incurvatum	H.lushuiensis	H.benghalensis
Leaf blade	elliptic to oblong, 4.0–12.0 × 2.0–5.0 cm, 2 glands	elliptic, 6–12 × 5–4.5 cm, 10–16 glands	elliptic, 9–16 × 3.5–5.0 cm, 2 or more glands at the base	oblong, elliptic-oblong, or ovate-lanceolate, 9–18 × 3–7 cm, 2 glands
Branchlet	densely rusty tomentose	white to grey sericeous	white to grey sericeous	densely yellowish brown or silver-gray sericeous
Bracteole	lanceolate, ca. 0.5 cm long	lanceolate, 0.3–0.5 cm long	lanceolate, ca. 1.5 mm long	acute, 0.2–0.4 cm long
Pedicel	yellow-brown sericeous, 1.5–2.0 cm long	white sericeous, 1.5–2.5 cm long	white sericeous, ca. 1.5 cm long	sericeous, 0.8–2.5 cm long
Calyx gland	10(-12), two large, ca. 3.0 ×1.0 mm, basally coalescent two smaller adnate to the apex of the two big glands separately, 0.4–0.5 mm diam.; remaining glands 1.8–2.0 × 0.8–1.0 mm, oblong; not decurrent to the pedicel	4-(6), two large, ca. 3.0 × 1 mm, basally connate, remaining glands 0.4–0.5 mm diam., round; not decurrent to the pedicel	2, ca. 1 mm diam., free, sometimes with additional smaller glands on the other sepals, not decurrent along the pedicel	1, very large, oblong, lanceolate to oblanceolate; more or less 1/2 adnate onto the pedicel
Sepal	elliptic to oblong, ca. 0.5 cm long	elliptic to oblong, ca. 0.5 cm long	elliptic, 0.4–0.5 cm long	broadly elliptic or ovate, 0.5–0.6 cm long
Petal	suborbicular, white to light white-pink, 1.0–1.5 × 0.8–1.2 cm	suborbicular, white to light white-pink, ca. 1 × 0.8 cm	suborbicular, pink, ca. 1 cm long	ovate-oblong to suborbicular, white, ca. 1 cm long
Claw	1 mm long, pubescent	1 mm long, pubescent	1 mm long, pubescent	1–2 mm long, glabrous
Posterior lateral wing	oblanceolate, ca. 4.2 × 0.8 cm	ovate, ca. 3.6 ×1.3 cm	ovate, ca. 3.5 × 1.3 cm	oblong, elliptic or obovate-lanceolate, 3–5 × 1–1.6 cm
Anterior lateral wing	lanceolate to linear, straight, ca. 2.5 × 0.4 cm	lanceolate, arcuate back to the middle, ca. 2.3 × 0.7 cm	lanceolate, ca. 2.0 × 0.9 cm	lanceolate-oblong, 1.5–3 cm long