Table 1 Morphological characteristics of S. kunthiana (Nees) T. Anders

1

Habit

Bushy shrub, 0.75–2 m high, branches stout in stray clumps or gregarious, glabrous, erect, rigid, quadrangular; nodes prominent, sparsely lenticellate, usually with light purplish tinge, usually angular or quadrangular upwards. Stem glabrous to sparsely pubescent, usually only so in the grooves and on nodes; lenticels and leaf scars sometimes prominent (Venu 2006; Singh and Arigela 2019; Carine et al. 2004; Augustine et al. 2017).

2

Leaves

Leaves elliptic-ovate, 2.5–8 × 1.5–4 cm, acute at base, crenate-serrate at margin, apex very short acuminate; coriaceous, scabrid above, white-villous between veins beneath; veins 4- 10 pairs, both primary and secondary veins prominent on abaxial surface, somewhat less so on adaxial surface; petiole 0–5.4 mm long, glabrous or with stout tapering hairs, especially along margins, symmetrical; margins subentire to prominently serrate; abaxial surface sparsely to densely covered with a white farinose indumentum, adaxial surface glabrous or sparsely covered with stout tapering hairs (Venu 2006; Singh and Arigela 2019; Carine et al. 2004; Augustine et al. 2017).

3

Inflorescence

The inflorescence spike branched or unbranched with many flowers. Spikes in upper axils and terminal, 3–10 cm long, uninterrupted, sometimes branched, white tomentose, subtended by leafy bracts;

4

Bract

Bracts 1–1.5 cm long, elliptic-ovate, white villous, midrib not prominent.

5

Bracteole

Lanceolate, 10 mm long, shorter than calyx, floccose at margin and middle, midrib not prominent.

6

Calyx

Lobes 10–14 mm long, divided almost half from the base, floccose-villous, linear-lanceolate (Singh and Arigela 2019).

7

Corolla

Corolla 2–3 cm long, somewhat campanulate, pale blue or pale lilac or mauve, nerves darker, pubescent outside, hairy inside at nectar guide area; lobes 5, orbicular or suborbicular, upper margin undulate.

8

Androecium

Staminal filaments not grooved, pilose hispid.

9

Pollen

Ellipsoidal, 60–86 × 40–53 μm, 3-zonoporate pseudocolpi 5 in each mesocolpium, ridges 2.19 μm broad

10

Gynoecium

Ovary hairy at the apex, style 15 mm long, swollen areas absent.

11

Fruits

Capsules 1–2 cm long, narrowly ellipsoid; seeds 4, 1.5–2 mm across, orbicular, brownish, flattened (Augustine et al. 2017).