Kalanchoe × toelkenii Gideon F.Sm., 2023

Smith, Gideon F., 2023, In search of enhanced material: Kalanchoe × toelkenii (Crassulaceae subfam. Kalanchooideae), a new South African nothospecies derived from Kalanchoe × gunniae × K. sexangularis, Phytotaxa 619 (3), pp. 241-249 : 245

Kalanchoe × toelkenii Gideon F.Sm. nothospec. nov. ( Fig. 2A–E ).

Type:— SOUTH AFRICA. Gauteng Province.—2528 (Pretoria): ex hort. Tshwane , (– CA), 28 June 2022, G. F . Smith 1189, (holotype PRU) .

Parentage:— Kalanchoe × gunniae Smith & Figueiredo in Smith et al. (2019b: 147) × Kalanchoe sexangularis Brown (1913: 120) .

Diagnosis:—A robust, biennial to multi-annual, ultimately monocarpic, rarely a polycarpic perennial, nothospecies that is intermediate between its parents, Kalanchoe × gunniae and K. sexangularis . Kalanchoe × toelkenii differs from K. × gunniae by being much more branched, especially higher up; and by having slightly smaller leaves that, along with the stems and branches, have a much more intense red infusion. The inflorescence structure of K. × toelkenii is similar to that of K. × gunniae , but its spread is much wider than that of the latter, a character inherited from K. sexangularis . Kalanchoe × toelkenii differs from K. sexangularis by being in all vegetative characters more robust; by the red-infusion of the leaves, stem, and branches being less pronounced; by the corollas that only reach a length of 11 mm, not 17 mm; and by ultimately being monocarpic or, rarely, a polycarpic perennial.

Description:—Biennial to multi-annual, ultimately monocarpic, rarely polycarpic perennial, few- to manyleaved, branched, glabrous, robust succulent, to 2.0 m tall. Stem single, light green to yellowish green with strong red infusion, erect to leaning, longitudinally ridged often prominently so, arising from a brittle, corky base. Branches produced lower down, but especially higher up. Leaves opposite-decussate, petiolate, light green to yellowish green, distinctly infused with red, especially when under environmental stress, succulent, spreading to recurved, coriaceous and papery on drying; petiole 5–50 mm long, channelled above, leaves not clasping the stem; blade 40–100 × 20–60 mm, broadly elliptic to obovate to oblong, somewhat to distinctly folded lengthwise, recurved in upper half; apex rounded-obtuse; base narrowly triangular to cuneate; margins coarsely crenate or undulate-crenate into rounded, nonpungent, crenations. Inflorescence a broadly spreading, flat-topped thyrse with several dichasia, 0.75–1.50 m tall, erect to leaning, apically dense, many-flowered, round to somewhat ellipsoid in outline when viewed from above, branches opposite, slanted away from main axis at 45–60°, subtended by leaf-like bracts, without, or more rarely with, leafy branchlets in axils; peduncle light green to yellowish green to strongly red-infused; pedicels slender, 5–6 mm long. Flowers erect; calyx consisting of 4 sepals, uniformly shiny light green, not strongly infused with small red spots; sepals basally fused for ± 1 mm, 2.5–3.0 × 1 mm, triangular-lanceolate, acute-tipped, hardly contrasting against corolla tube; corolla 9–11 mm long, distinctly enlarged lower down, not twisted apically after anthesis; corolla tube 8–10 mm long, greenish yellow, distinctly 4-angled, box-shaped-square when viewed from below, longitudinally distinctly fluted above; corolla lobes 2 × 2 mm, ± round, rounded at apex, apiculate, yellow, sometimes faintly browntipped. Stamens inserted well above middle of corolla tube, included; filaments 2–3 mm long, thin, light green; anthers 0.3–0.5 mm long, greenish yellow. Pistil consisting of 4 carpels; carpels 5–6 mm long, light green; styles 2–3 mm long; stigmas very slightly capitate, whitish yellow; scales ± 1.0– 1.5 mm long, linear, uniformly light yellowish. Follicles basally box lantern-shaped, margins reddish infused, brittle, grass spikelet-like when dry, initially light green to dull whitish green, enveloped in light brownish white dry remains of corolla, later drying light to dark brown, 7–10 mm long. Seeds 0.5–1.0 mm long, reddish brown to dark brown, cylindrical to club-shaped to slightly banana-shape curved. Chromosome number: unknown.

Flowering time:— Kalanchoe × toelkenii flowers from late-April to September, i.e., from late-autumn to spring in the southern hemisphere, peaking from mid- to late-June to July.

Eponymy:— Kalanchoe × toelkenii is named for Dr Hellmut Richard Toelken (Windhoek, Namibia, 1 September 1939 –) ( Fig. 2F ) who authored the account of the Crassulaceae , including of Kalanchoe , for the Flora of Southern Africa project ( Tölken 1985). Hellmut completed a B.Sc. degree at Stellenbosch University, and thereafter successively obtained B.Sc. (Hons), M.Sc., and Ph.D. degrees from the University of Cape Town. For his Ph.D. dissertation he studied the genus Crassula in southern Africa, the results of which were published in two parts ( Tölken 1977a, b). From 1963 until 1967 Toelken was employed by the Botanical Research Institute (BRI), after which he lectured at the University of Cape Town until 1973. From September 1973 until 1979 he was again attached to the BRI, including completing a stint as South Africa’s Botanical Liaison Officer at the Royal Botanic Gardens, Kew, from June 1974 until July 1976. In 1979 Toelken emigrated to Adelaide, Australia ( Gunn & Codd 1981: 351), where he inter alia studied the local Crassulaceae . He also contributed to, and was co-editor of, Flowering Plants in Australia and Flora of South Australia.

Figures

FIGURE 2. Kalanchoe ×toelkenii. A. Stems are vertically ridged, which assists with retaining plants in an erect position. B. Plants are shrub-like branched, especially higher up, rather than unbranched. C. When compared to K. ×gunniae, all plant parts are more intensely red-infused. D. The inflorescence branches diverge at an angle of about 45–60° from the vertical, as in K. sexangularis. E. Flowers are borne erectly and densely towards the apex of the inflorescence branches. F. Hellmut Richard Toelken (Windhoek, Namibia, 1 September 1939–), after whom K. ×toelkenii is named. All photographs: Gideon F. Smith, except ‘F’, which was supplied by H.R. Toelken.