Kalanchoe × sampsonii Gideon F.Sm., 2023

Smith, Gideon F., 2023, Kalanchoe × sampsonii [K. × hankeyi × K. sexangularis] (Crassulaceae subfam. Kalanchooideae), a horticulturally successful nothospecies from South Africa with enhanced vegetative and reproductive characters, Phytotaxa 584 (4), pp. 293-300 : 295-297

Kalanchoe × sampsonii Gideon F.Sm. , nothospec. nov. ( Fig. 2A–F )

Type:— SOUTH AFRICA. Gauteng province —2528 (Pretoria): Tshwane , (–CA), ex hort., 17 May 2022, G.F. Smith 1184 (holotype PRU) .

Parentage:— Kalanchoe × hankeyi Smith (2020d: 93) × Kalanchoe sexangularis Brown (1913: 120) .

Diagnosis:— Kalanchoe × sampsonii is a medium-sized, perennial nothospecies that is intermediate between its parents, K. × hankeyi and K. sexangularis , but with several characters enhanced so yielding material with improved horticultural potential. It differs from K. × hankeyi by its leaves usually being larger, especially in width, longitudinally folded as in K. sexangularis , rather than ± flat, and generally distinctly red-infused, but less so than in K. sexangularis . In terms of reproductive morphology, K. × sampsonii differs from both K. × hankeyi and K. sexangularis by its inflorescences being much more densely branched and the branches have a wider spread. The flowers of K. × sampsonii are larger than those of K. × hankeyi and K. sexangularis , but generally smaller than those of K. longiflora , one of the parents of K. × hankeyi . In K. × sampsonii the corolla tube and corolla lobes are more intensely yellow than in either of its parents, where especially the tube colour is variously subdued by greenish infusion.

Description:—Perennial, many-leaved, usually densely branched, glabrous, medium-sized to succulent shrublets, (0.2–) 0.3–0.5 m tall when not in flower. Stems and branches mid- to light green to somewhat to strongly red-infused, erect to leaning under weight of branches, often with several lengthwise running ridges especially when young, 4- angled in sterile shoots and higher up in stem-peduncle transition, thickened at internodes, leaf scars obvious, whitish grey. Leaves opposite-decussate, petiolate, mid-green, often red-infused, succulent, erectly spreading, recurved, coriaceous and papery on drying; petiole (15–)20(–30) mm long, channeled above, leaves not clasping stem, very slightly thickened where attached to stems and branches; blade 120–135(–150) × (65–)80–90(–100) mm, generally broadly elliptic, somewhat folded lengthwise, recurved in upper half; base narrowly triangular to cuneate throughout; apex rounded-obtuse, usually with soft tip; margins undulate-crenate into distinct, rounded, harmless, tooth-like crenations in upper ¾ to ⅞, teeth becoming smaller to obsolescent towards leaf base and tip. Inflorescence 0.5–0.8 m tall from base of peduncle, robust, multi-branched, erect to leaning, apically dense, many-flowered, ± flat- to roundtopped thyrse consisting of several dense dichasia, round to rather ellipsoid in outline when viewed from above, branches opposite, erectly ascending at an angle of 30–45°, subtended by strongly red-infused leaf-like bracts that are initially persistent but eventually shed, without, or very rarely with, leafy branchlets in axils, axis light to mid-green to red-infused; pedicels 5–9(–10) mm long, slender. Flowers erect, bright yellow-tipped in bud, copiously nectariferous; calyx shiny, uniformly light green, not contrasting against corolla base, sepals 2.0 × 1.5 mm, triangular-deltoid, ± separate, basally adnate to fused for ± 1 mm, acute-tipped; corolla 16–19 mm long, enlarged lower down (not inflated), not twisted apically after anthesis, tube 14–17 mm long, greenish yellow, distinctly 4-angled, box-shaped-square when viewed from below, longitudinally fluted above, lobes 4.0–4.5 × 3.5–4.5 mm, uniformly bright yellow, ovate to subcircular, ± rounded at apex, apiculate, slightly to distinctly recurved. Stamens 4, inserted in two distinct ranks well above middle of corolla tube; filaments 2–3 mm long, thin, greenish yellow; anthers 0.50–0.75 mm long, light yellow before anthesis, turning yellowish grey post-anthesis, slightly exserted. Pistil consisting of 4 carpels; carpels 7–8 mm long, light green; styles 5.5–7.0 mm long; stigmas distinctly capitate, whitish yellow; scales ± 3.0– 3.5 mm long, linear, gradually tapering upwards, yellow. Follicles 9–11 mm long, initially light green, later brittle, grass spikelet-like, enveloped in dry, light brown to grey remains of corolla. Seeds 0.50–0.75 mm long, reddish brown to dark brown, tapering to both ends, oval to banana-shaped curved in outline, faintly striated. Chromosome number: unknown.

Eponymy:— Kalanchoe × sampsonii is named for Mr Jason David Stephan Sampson (10 February 1979, Pietermaritzburg, KwaZulu-Natal, South Africa –) ( Fig. 2H ). Mr Sampson grew up in Roodepoort in central Gauteng on South Africa’s West Rand and after matriculating read for a B.Sc. degree in Botany and Earth Sciences at the Potchefstroom University for Christian Higher Education, now the Potchefstroom campus of the North-West University. He is currently enrolled for a Master’s degree in Horticulture at the University of Pretoria. In 2010, Jason assumed the curatorship of the Manie van der Schijff Botanical Garden of the University of Pretoria where he has developed several large-scale, waterwise projects such as the rainwater harvesting garden and the cremnophyte-based green walls of the new Plant Science building (see Smith & Figueiredo 2020: 253). Several of Mr Sampson’s projects have received industry awards. Jason has a longstanding interest in xeriscaping, especially with a range of succulents ( Sampson 2018: 10). He has introduced a large number of aloes and kalanchoes, including material of K. × estrelae Smith (2020a: 225) ( Fig. 2H ), to cultivated beds on the Hatfield campus of the University of Pretoria.

Flowering time:— Kalanchoe ×sampsonii flowers mainly in the autumn and winter months, (March–)April to August in the southern hemisphere.

Horticulture:— Kalanchoe × sampsonii responds well to cultivation and once material propagated through stem cuttings is rooted virtually no after care is required. The horticultural appeal of K. × sampsonii is centred on its more intensely reddish-infused leaves and peduncles, the extensive branching and spread of the inflorescences, and larger and more intensely coloured (bright yellow) corolla tube and corolla lobes. In addition, K. × sampsonii attracts a range of birds and insects to a garden ( Smith 2022g) and does not show any invasive tendencies (see Smith et al. 2021c).

Figures

FIGURE 2. Kalanchoe ×sampsonii. A. At flowering maturity plants of this shrubby nothospecies reach a height of about 0.5 m. B. Through heterosis, inflorescences are more branched and have a wider spread than in either of the parents. C. Peduncles are more intensely reddish-infused than in K. ×hankeyi, but less than in K. sexangularis. D. Flowers (corolla tube and corolla lobes) are more intensely yellow than those of either of the parents. E. Flowers, here in lateral view, of K. ×sampsonii (centre) are often intermediate between those of K. longiflora (left, one of the parents of K. ×hankeyi) and K. sexangularis (right), but the corolla tube is more intensely yellow. F. Corolla lobes of K. ×sampsonii (centre) are more intensely yellow than those of K. longiflora (left, one of the parents of K. ×hankeyi) and K. sexangularis (right, the other parent of K. ×hankeyi). G.A White-bellied sunbird, Cinnyris talatala, feeding on the copiously nectariferous flowers of K. ×sampsonii. H. Jason D.S. Sampson (1979–), after whom K. ×sampsonii is named, next to a very large specimen of K. ×estrelae on the Hatfield campus of the University of Pretoria; photograph taken on 10 June 2022. All photographs taken by Gideon F. Smith.