Table S1. Morphological differences between Silene leucophylla and Silene schimperiana and the nearest elements of the genus Silene. Species Name Stem Leaves Inflorescence Flowers Capsule Pedicel to 7mm; calyx Basal leaves, oblong-cylindrical, pubescent densely 1.2-1.9 x 0.1-0.3cm., 10 rosette ovate to nerved, hairy, calyx Viscid, Perennial, spathulate, rarely teeth triangular or tomentose-canescent orbicular 0.6−3 × ovate-deltoid, obtuse, with woody 0.1−0.8 cm; petiole Inflorescence with scarious Capsule structure at the base 0.4−3 cm. long, olive cymose; with 3-5 margins; ca. 3 mm oblong ovoid Silene leucophylla up to 30 cm long. color, with acute apex flowers, pedicelled; long. Petals 5 purple capsule 1.9 Stem, erect, hairy, and entire margins. Pedicel length 0.4−0.7 to whitish violet to cm. long cylindrical, Cauline leaves ovate cm. violet, 2.8−5.5 cm long internode length 2−5 to spathulate 0.3−1.2 × (with claw length cm, stems to 40 cm. 0.1−0.5 cm. opposite 0.5−0.7 cm and limb decussate, petiolate, 2−2.3 cm. long). with acute apex and Carpophore equaling entire margins. the capsule. Calyx 11.5-15 mm, Basal leaves rosulate, with an indumentum Caespitose perennial, oblanceolate- of short glandular stems erect, slender, spathulate, canescent Inflorescence a hairs, 10-nerved, the Capsule 25-35 cm, with an sericeous; dichasium, the main teeth broadly Silene leptoclada oblong, 8-9.5 indumentum of cauline leaves axis terminating in a triangular. mm. short, spreading narrowly oblanceolate flower. 2-5 flowers Petals bifid. petal hairs. to very narrowly limb yellowish elliptic, distant. Anthophore 2.5-3.5 mm. Basal leaves rosulate, Caespitose perennial, oblanceolate- Calyx 9-10 mm, very stems erect, slender, spathulate, canescent shortly puberulous, Inflorescence very Capsule 25-35 cm, with an sericeous; cauline anthophore ca. 2 mm. Silene flavescens reduced and raceme- oblong, 8-9.5 indumentum of leaves narrowly Petal yellowish white like mm. short, spreading oblanceolate to very to greenish- yellow hairs. narrowly elliptic, above distant. Calyx 10-ribbed, 13- 15mm, white, gland, Basal leaves arranged slightly inflated in in rosettes, leaves fruit, glandular- pubescent; the lamina villous, especially on Densely villous broadly cuneate, 15-30 the ribs; calyx teeth perennial; stems 10- x 10-20mm, apiculate, Flower solitary or in triangular-lanceolate, 45cm, arising from a villous, more densely 2-5-flowered lax ca. 2mm, acute. Capsule ovate Silene yemensis woody base, densely so on the margins and dichasial cymes; Corolla pink to ll-12mm long; villous below, midrib, glandular pedicels up to 20mm, brownish, c.20mm; glandular-villous above, contracted glandular-villous. limb ca. 7mm, above. below into a 10-40mm glabrous, divided in petiole; cauline leaves the top third into 2 much reduced sessile, linear lobes. linear-lanceolate. carpophore 4-6mm, glabrous. Flowers greenish- white above, reddish- Perennial, pubescent green underneath, at base, carpet- calyx club-shaped, forming, woody vestige of calyx, rootstock; 10-20 cm, glabrous, whitish, 10 Leaves linear or Two or dichotomous, many stems, spindly, branching veins, oval- Capsule linear-lanceolate, solitary or twinned, Silene saxifraga viscous at the top; obtuse teeth; bifid ovoid or pointed ciliated, rough 2-3 flower peduncle caudiculis petals, crowns of oblong, edges long suffruticosae obtuse scales, no complicated auricle to body, but prostrales, stems are ciliated; the delicate slender filiform glabrous carpophore equaling capsule. anthophore 3-4 mm Basal leaves lanceolate, 0.4-4.5 x Calyx tubular 0.8 -1.2 0.1-0.9 cm. arranged in cm long, 10 nerved rosette shape with with yellow nerve, Perennial, with acute apex, entire hairy. Bract woody structure at margins, symmetrical lanceolate. Petals 5 Inflorescence the base up to 25 cm. base and sessile. white in color with Capsule racemes, pedicle; Silene oreosinaica long. Stem, hairy, Cauline leaves very pale pink edges ovoid 0.8 -1.2 Pedicel length 0.5 cm cylindrical; lanceolate, smaller 1.1-1.9 cm long (claw cm. long. long. internode up to 5 cm than basal leaves 0.4- 0.4-0.6 cm long and long. 2.5 x 0.1-0.2 cm, limp 0.7-1.2 cm long). opposite decussate Petals that exposed to with acute apex, entire the sun are converted margin, symmetrical to rose color base and sessile Calyx oblong- cylindrical 2-2.5 mm, 10 nerved, glabrous, Basal leaves 4-10 x 0.3- dimorphic, calyx 0.5cm, narrowly teeth, triangular with linear-spathulate, Flowers in lax acute apex 2–3 mm. Perennial glaucous, acute, with a paniculate cymes, long; Petals 2-fids, Capsule 1.3- herb, woody at the prominent midrib on solitary or rarely 2 Petals five white in 1.5cm, Silene schimperiana base, stems 50-80cm, the lower surface. together, subtended the upper side and oblong, erect rigid branching Cauline leaves linear by 2-minute yellowish in the back glabrous thicker at the nodes to spathulate, opposite bracteoles; pedicel side, sometimes with decussate, with acute 1.5-2cm; violet nerves, 3.5-5.2 apex, entire margin, cm. long (with claw symmetrical base. length 1.5 - 2.7 cm and limp 2 -2.7 cm.); carpophore equaling the capsule. Basal leaves linear to Calyx 13-18(20) mm. Inflorescence Capsule 9-15 Caespitose perennial, oblanceolate, narrow. Petals bipartite to the racemose, sometimes mm, stems up to 50 cm, Cauline leaves linear, middle, whitish or Silene armena paniculately sometimes stems glabrous, very narrow, margins yellowish. glabrous branched. Bracts slightly viscid serrulate or papillose- calyx. Anthophore linear. exerted scabrid above. (4)5-9 mm. Perennial with many erect, slender stems arising from a very Calyx 3-4 mm, Inflorescence woody branched glabrous, ovoid. Cauline leaves linear, paniculate, the Capsule 3-4 base. Stems up to 30 Petals yellowish Silene tunicoides setaceous, 10-15 mm, branches wide- mm, included cm, with short, green, with an entire margins setose. spreading and in the calyx. retrorse limb. Anthophore 1 cymose. indumentum below, mm or less. glabrous, and viscid above. Calyx 11-15 mm, nerves conspicuous, the teeth broadly triangular with dense, Basal leaves forming a Rigid annual. Stems anastomosing rosette, spathulate, Capsule erect, up to 50 cm, venation, glabrous. petiolate, often Inflorescence richly ovoid- Silene vittata puberulent below, Petals pink, puberulent; cauline dichasial branched. globose, 7-8 glabrous and often conspicuously leaves linear to linear- mm. viscid above. purple-veined lanceolate. outside; coronal scales dentate-incised. Filaments glabrous. Anthophore 6-10 mm. Basal leaves small, Calyx 20-22 mm. soon withering. Petal limb bipartite to Cauline leaves more the middle into Capsule than 3 x longer than Perennial, up to 80 Inflorescence a oblong lobes. oblong, Silene caesarea broad, lanceolate to cm, viscid above. spreading panicle Anthophore 8-10 mm, exerted from oblong-lanceolate, shorter than the calyx acute, cordate at the exserted capsule. base, more than 5 mm Petals white broad. pale green, sometimes purple-and rosettes of Calyx 17, 5-26,5mm leaves suffused. long, cylindrical, Individual or more. Inflorescence panicle green colored, often Capsule 11 - Basal 32- 4- 75 × 10 flowered spreading. violescent. The teeth 17 × 4,5 - 6 mm, sub-spathulate as Bracts 3-5 cm long, are alternately 2,5-4,5 mm long, Perennial. Up to a far as oblanceolate, linear triangular, mm long, obtuse and ovoid, Silene farsistanica few more woody attenuate into a sharp, and the wider acute angle ± Peri- slightly 100 cm tall, petiole; cauline leaves towards the base of wide margins. Petals protruding (36) 30 - 56 (70) × 5 - 9 the hyaline white or yellow; limb from the mm oblong-oval or margined. c. 10 mm long, calyx; oblong-lanceolate fingernail c. 13 mm petiolate or nearly high. acute; All the leaves are fleshy. Basal leaves small, soon withering. Calyx 12-23 mm. Capsule 13-17 Glaucous, glabrous Median cauline leaves Petals white to khaki, Inflorescence x 5-6 mm, perennial. Stems up to 2 (2.5) x longer the limb bipartite into Silene laxa racemose or somewhat erect, viscid above, than broad, ovate to oblong-obovate lobes. paniculate, lax. exerted from 70-100 cm. elliptic, cordate at the Anthophore 6-9.5 the calyx base, acute, more than mm. glaucous calyx 10 mm broad. Leaves dimorphic, the Calyx 12-16 mm. basal obovate to Capsule 7-8 x Caespitose, glabrous Inflorescence Petal limb divided to broadly elliptic, 4 mm, Silene lycaonica perennial. Stems racemose, few- beyond the middle fleshy, the cauline included in erect, c. 25 cm. flowered. into oblong lobes. very reduced, linear to the calyx. Anthophore 6-7 mm. lanceolate. Table S2. Quantitative characteristics of stem and leaf Abaxial leaf (AB) and Adaxial leaf (AD) characters of Silene leucophylla and Silene schimperiana. Character Abbreviations Silene leucophylla Silene schimperiana Mean SD Median Min Max Range SE Mean SD Median Min Max Range SE Stem characters Stomatal Pore Length SPL 10.57 2.5 10.09 7.67 14.4 6.73 1.12 13.55 2.81 13.32 10.85 16.47 5.62 1.63 Stomatal Pore Width SPW 1.89 0.87 1.33 1.16 2.88 1.71 0.39 1.47 0.46 1.72 0.95 1.75 0.8 0.26 Stomatal Pore Area SPA 14.19 7.09 12.33 7.38 25.1 17.72 3.17 14.71 8.04 18.75 5.45 19.93 14.48 4.64 Stomatal Complex Length SCL 21.9 2.16 21.9 20.37 23.43 3.05 1.53 19.05 2.67 17.78 17 23.49 6.49 0.94 Stomatal Complex Width SCW 5.66 1.59 5.66 4.53 6.78 2.25 1.13 6.21 1.11 6.02 4.65 7.97 3.32 0.39 Stomatal Complex Area SCA 107.40 29.41 107.4 86.61 128.19 41.59 20.79 88.84 17.83 89.65 63.05 119.72 56.66 6.31 Abaxial leaf (AB) characters Stomatal