Kalanchoe × gildenhuysii Gideon F.Sm. & Figueiredo, 2020

Kalanchoe × gildenhuysii Gideon F.Sm. & Figueiredo View in CoL nothospec. nov.

Parentage:— Kalanchoe millotii Raymond-Hamet & Perrier de la Bâthie (1912: 374) × Kalanchoe tomentosa Baker (1882: 110) .

Type:— SOUTH AFRICA. GAUTENG PROVINCE.—2528 (Pretoria): Pretoria, (–CA), ex hort., 11 September 2019, G.F. Smith 1090 ( PRU; holo-) .

Diagnosis:—Plants are small to medium-sized, perennial, and intermediate between Kalanchoe millotii and K. tomentosa . They differ from K. millotii by the leaves being more lanceolate, rather than obovate to orbicular, and basally cuneate rather than truncate; by having brown-tipped teeth on the leaf margins; and corollas that are lighter green and pink-infused. Kalanchoe × gildenhuysii differs from K. tomentosa by having broader leaves, distinctly toothed leaf margins, and smaller flowers that are more muted in colour.

Description:—Perennial shrublets, usually densely branched, with haphazardly rounded canopies, succulent, 0.3–0.4(–0.5) m tall when not in flower. Stem branched from the base or higher up, comparatively robust, to 5–10 mm in diameter, ± erect or variously leaning outwards, prominently and densely covered by fine, golden-brown, velvety hairs, leaf scars obvious, light greyish green. Leaves decussate, rather densely arranged, many, carried especially towards terminal ½ to ⅔ of stems and branches, slowly shed lower down to yield small, light green leaf scars, gracefully curved upwards to erect especially when young to variously slightly spreading when older, succulent, densely pubescent, ± petiolate, sometimes obscurely so, dull light green to light yellowish green, pubescence with a golden sheen; petiole same colour as leaf blade, succulent, ± flattened above, slightly grooved, rounded below, groove extending into blade, 5–10 mm long, basally not or hardly enlarged; blade 70–90 × 20–35 mm, ovate to lanceolate-ovate to slightly obovate, never orbicular, flat to concave above, convex below, succulent; base cuneate; apex bluntly acute-tipped; margins slightly curved upwards, ± regularly dentate in upper ½, teeth irregularly spaced, broad but always acute, concolorous, but with the very tips dark brown, transitional leaves on flowering stems with teeth along upper ⅓ of margins. Inflorescence a terminal, rather laxly branched, few- to manyflowered corymb, 55–70 cm tall, sometimes only one branch at a branching point, erect to gracefully leaning sideways and upwards; peduncle finely tomentose, light pink, leafy below branches, bract-like leaves on peduncle narrower and more lanceolate than vegetative leaves, pink, especially higher up on the peduncle; pedicels 3–4 mm long, light green, stout, densely pubescent. Flowers ± 16 mm long, ± erect or slanted in various directions, densely pubescent except adaxial surfaces of petal lobes, waxy bloom absent; calyx fused below, dull light green and strongly purplish-infused; sepals 5–7 mm long, elongated-triangular, fused below for ± 3–4 mm, acute, densely glandular-hairy, obscuring about ½ of the corolla tube; corolla light green lower down, especially where corolla obscured by calyx, strongly pink-infused higher up; tube 9–10mm long, cylindrical, more or less quadrangular-urceolate to elongated-urceolate, expanded in the middle, slightly tapering to the mouth, scarcely 4-angled; lobes 5–6 × 2–3 mm, ± rectangular, spreading to slightly recurved at maturity, not indented at the tips, mucronate, strongly pinkish-infused especially on the inside of the mouth, purplish pink veins obvious on the inside of the mouth. Stamens 8, inserted at ± middle of corolla tube in 2 ± obscure ranks, included; filaments ± 3–4 mm long, thin, flimsy, light yellowish green; anthers ± 0.50–0.75 mm long, hastate, yellow, included. Pistil consisting of 4 carpels; carpels 6–7 mm long, light green; styles 4.5–5.0 mm long, light green; stigmas very slightly capitate, whitish green; scales ± squarish-globular to trapeziform, not connate, ± 1.5×1.0 mm, slightly apiculate above. Follicles 5–7 mm long, dull light green at first, drying whitish green, brittle, grass spikelet-like, tightly enveloped in dry, persistent, creamy pink remains of corolla and light brown remains of calyx, splitting longitudinally, dry styles persistent for a long time. Seeds 0.75–1.00 mm long, light brown to reddish brown, tapering to both ends, oval to somewhat cylindrical in outline, sometimes bananashaped-curved, faintly longitudinally striated. Chromosome number: unknown. [Chromosome numbers of parents: the 2 n chromosome number of K. millotii has been recorded as “38?” ( Friedmann 1971: 105), while 2 n = 34 has been recorded for K. tomentosa ( Baldwin 1938: 576) .]

Flowering time:— Kalanchoe × gildenhuysii flowers from May to September, from early-winter to spring in the southern hemisphere, peaking in August.

Eponymy:— Kalanchoe × gildenhuysii is named for Mr Sean Dean Gildenhuys (Pretoria, Gauteng province, South Africa, 30 October 1983 –). He partly grew up in Nelspruit, Mpumalanga province, South Africa, and after returning to Pretoria in 2002 eventually completed a degree in horticulture at the Tshwane University of Technology. Sean has a longstanding interest in succulent plants and has contributed papers to Aloe , journal of the Succulent Society of South Africa. He has lectured widely on succulent plants in South Africa and Europe.

Horticulture:— Kalanchoe × gildenhuysii grows easily from cuttings and responds well to cultivation. Leaves of K. tomentosa will root and form small plants at the point severed from the stem, and this ability has also been observed in K. ×gildenhuysii . This eye-catching nothospecies has distinct horticultural potential. It thrives in full sun and in dappled shade and can be planted en masse to form a groundcover of medium height. Especially its densely pubescent, light green to light yellowish green foliage, which has a golden sheen in full sun, makes it very attractive.