| Height | 4-15 cm | 10-30 cm | 20-50 cm | 40-60 cm |
| Stems | solitary or 1-2 in clusters, erect, terete and densely glandular | multiple clusters, ascending to erect, terete or weakly angular, upper part minutely glandular | solitary or 2-3 in clusters, erect, woody at base, terete or weakly angular in upper part, densely glandular | 2 to many, erect, angular or winged, branched from middle, glabrous |
| Leaf blade | ovate or elliptical lanceolate, 1.5-3(4) x 0.5-1.6 cm; veins inconspicuously reticulate | ovate to rhomboid-ovate or ovate-elliptic, 1.5-3(-6) x 0.7-3 cm; veins prominently reticulate | elliptic-lanceolate to narrowly lanceolate, 3-11 x 0.7-2.8 cm; veins prominently reticulate | ovate to lanceolate, 1.5-3 x 1-3 cm; veins 4 or 5 pairs; veins inconspicuously reticulate |
| Petiole | 2-4 mm, minutely glandular | 4-8 mm, sparsely glandular | 5-15 mm, sparsely glandular | 2-8 mm, glabrous |
| Corolla | yellow, 6-8 mm, deeply parted; lobes narrowly elliptic or narrowly oblong, 5-8 x 1-2 mm, apex obtuse | yellow, 7-10 mm, deeply parted; lobes narrowly oblong, 6-9 x 2.7-4 mm, apex obtuse | yellow, 9-11 mm, deeply parted; lobes linear, 8-10 x 2-3 mm, apex obtuse | yellow, 6-8 mm, deeply parted; lobes narrowly oblong to linear, 5-7 x 1.8-3 mm, apex subobtuse |
| Calyx | lobes ovate-lanceolate, apex acuminate, 2 mm, surface glabrous except glandular hairy abaxially, margins sparsely glandular hairy, calyx yellowish-white in fruiting | lobes ovate, apex acuminate, 3.5-4 mm, surface glabrous, margins sparsely glandular hairy, calyx green in fruiting | lobes triangular, apex acuminate,2.5 mm, surface glabrous, margins sparsely glandular hairy, calyx green in fruiting | lobes ovate to lanceolate, apex acuminate to subulate, 2-4 mm, surface glabrous, margins minutely glandular hairy, calyx green in fruiting |
| Capsule | globose, 2-3 mm in diam., ca. as long as calyx | globose, 3-4 mm in diam., ca. as long as calyx | subglobose, 4 mm in diam., longer than calyx | globose, 3-4 mm in diam., longer than calyx |