Kalanchoe × kewensis Watson

Smith, Gideon F., 2023, The taxonomy and nomenclature of Kalanchoe × kewensis [K. bentii × K. glaucescens] (Crassulaceae subfam. Kalanchooideae), a nothospecies produced at the Royal Botanic Gardens, Kew, in the early 1900 s, Phytotaxa 618 (3), pp. 274-282 : 277

Kalanchoe × kewensis Watson (1902 [24 May]): 338–339) ( Fig. 1A–G )

Type:— SOUTH AFRICA. Gauteng province —2528 (Pretoria): Tshwane , (— CA), ex hort., 6 November 2019, G. F. Smith 1094, (neotype, Herb. PRU), here designated .

Parentage:— K. bentii C.H.WrIght ex HOOker (1901: tab. 7765) ♁ × K. glaucescens Britten (1871: 393) , as K. flammea Stapf (1897: 266) ♀

Heterotypic synonym:— Kalanchoe × kewensis Brown (1902 [14 June]: 387), nom. illeg. (Turland et al. 2018:Art. 53.1). Type :— GREAT BRITAIN. Royal Botanic Gardens , Kew, ex hort., June 1902, N. E. Brown s.n., (lectotype, K barcode K000838472 [image available at http://specimens.kew.org/herbarium/ K000838472 ]! and K barcode K000838473 [image available at http://specimens.kew.org/ herbarium/ K000838473 ]!), here designated.

Amplified description:—Perennial, few- to many-leaved, simple or, more rarely, sparsely to densely branched from base, glabrous throughout, small to medium-sized, erect to leaning, succulent shrublets, (0.4–)0.5–0.7(–1.2) m tall when in flower. Stems light to mid-green to reddish green, arising from base, especially once main stem initiates flowering, erect to leaning, smooth, round in cross-section, longitudinal ridges absent. Leaves 40–100 × 8–12 mm, mid- to dark green, opposite-decussate, sessile, not stem-clasping, reddish-infused if grown in exposed positions, somewhat shiny, succulent, spreading to slightly erect, brittle when dry; petiole absent; blade of lower leaves oblanceolate, margins irregularly toothed, blade of upper leaves cylindrical-elongated to lanceolate,tapering to both ends, ± round to cymbiform in cross-section, with prominent, curved, harpoon-like outgrowths ± halfway up, pointing to leaf tips; base cuneate; apex blunt-tipped; margins rounded, adorned with irregularly-shaped teeth or prominent outgrowths. Inflorescence an erect to leaning, apically dense, many-flowered, flat-topped, cyme, 100–140 mm tall, branches opposite or alternate, erectly slanted away from vertical at 45º angle, subtended by narrow, leaf-like bracts, often with leafy branchlets in axils, axis green to reddish green; pedicels 3–6 mm long, stout. Flowers erect, tricoloured, not diurnal, often abnormal; calyx consisting of 4 sepals; sepals 6–7 mm long, dull mid-green, strongly infused with small red spots especially towards tips and margins ± separate, basally hardly adnate for ± 0.50–0.75mm, lanceolate to elongated-triangularlanceolate, acute-tipped, flared away from tube, somewhat contrasting against corolla tube; corolla somewhat enlarged lower down at level of ovary, slightly twisted apically after anthesis; corolla tube 15–16 mm long, light green (lower ½ of tube), yellowish green to bright pink-infused (upper half of tube), 4-angled, rounded to slightly box-shaped-square when viewed from below, slightly longitudinally fluted above; corolla lobes 9–10 × 6–7 mm, uniformly bright vibrant pink, margins sometimes white, ovate to slightly oblong-ovate, carried patent-erect, unevenly rounded-acute at apex, mucronate, twisted in bud. Stamens inserted in two distinct ranks slightly above middle of corolla tube, included, visible at mouth of corolla tube; filaments 3.0– 3.5 mm long, thin, yellowish green; anthers 0.50–0.75 mm long, hastate to ovoid, light green, turning dark yellowish brown when pollen is shed. Pistil consisting of 4 carpels; carpels 6–7 mm long, light to mid-green; styles 3–4 mm long, light yellowish green; stigmas capitate, light yellowish green, visible at mouth of corolla tube; nectar scales ± 3–4 × 0.75–1.00 mm, rather linear, light yellowish, contrasting against green carpels. Follicles 7–9 mm long, light green at first, drying light brown to reddish brown, later brittle, grass spikeletlike, tightly enveloped in dry, persistent, creamy white to straw-coloured remains of corolla and reddish brown remains of calyx, splitting longitudinally, dry styles persistent for a long time. Seed 0.50–0.75(–1.00) mm long, light brown to reddish brown, tapering to both ends, oval to somewhat cylindrical in outline, often banana-shaped-curved, minutely apiculate, faintly longitudinally striated [however, seed appears to be substantially sterile and this nothospecies is likely self-sterile (see also Heijnsdijk 2022: 66), unlike most Kalanchoe species and even nothospecies, see Smith et al. 2021: 3, 13, 17 and Smith 2022c:172)]. Chromosome number: unknown.

Figures

FIGURE 1. Kalanchoe ×kewensis [Arabian material of K. bentii, i.e., K. bentii subsp. bentii, × K. glaucescens]. A. Plants are usually single-stemmed and can (rarely) reach a height of 1.2 m when in flower. B. Leaves are cylindrical-elongated to lanceolate, taper to both ends, and, at maturity, ± halfway up, have prominent, curved, harpoon-like, lateral outgrowths that point towards the leaf tips. C. In some specimens branching may take place from the base. D. Close-up of buds and a flower at anthesis. The sepals are flared away from the tube. The ovate to slightly obovate corolla lobes are uniformly bright vibrant pink, but could sometimes be adorned with narrow, white margins. E. Flowers often develop abnormally, for example with all four corolla lobes concentrated to one side of the apex of the corolla tube, or they deviate by being pentamerous, rather than tetramerous, the latter condition being prevalent virtually throughout in Kalanchoe. Such deviations in floral morphology are often found in hybrid kalanchoes. F. A plantlet that developed just below the desiccated inflorescence. G. The follicles are tightly enveloped in the dry, persistent, creamy white to straw-coloured remains of the corolla and the reddish brown remains of calyx. All photographs: Gideon F. Smith.