Kalanchoe steyniae Gideon F.Sm. & N.R.Crouch

Smith, Gideon F. & Crouch, Neil R., 2024, Kalanchoe steyniae (Crassulaceae subfam. Kalanchooideae; K. [subg. Kalanchoe sect. Raveta] ser. Rotundifoliae), a new, small-growing, shrubby species from eastern southern Africa, Phytotaxa 659 (3), pp. 268-276 : 272

Kalanchoe steyniae Gideon F.Sm. & N.R.Crouch , sp. nov. ( Figs 2A–D , 3A–B ).

Type:— SOUTH AFRICA. KwaZulu-Natal province. Northeastern region of the province, on rocky substrates, ca. 250 m above sea level [asl], 02 July 2019. Gideon F. Smith 1222 (holotype, Herb. PRU!).

Diagnosis:— Kalanchoe steyniae differs from K. rotundifolia in especially reproductive characters, with its flowers being densely arranged (not diffusely so) in ± flat-topped, corymbose cymes; its corolla lobes showing weak (not substantial) diurnal movement; and its corolla tubes and corolla lobes being bright crimson red (not dull red to orange).

Description:—Perennial, many-leaved, sparsely branched from base or higher up, glabrous, small, low-growing, succulent shrublet, 130(–200) mm tall, to 500 mm when in flower. Stems and branches erect to erectly spreading, light brown to pinkish, brittle-woody at maturity, 4–7 mm in diam., sometimes developing stilt-like roots. Leaves (15–)20–30(–35) × (10–) 12–14 mm, greenish yellow, opposite-decussate, sessile or with very short petiole, erectly spreading at 45° angle, densely carried throughout, severed leaves sprouting plantlets from proximal end; petiole ± absent or to 2 mm long; blade succulent, obovate, straight, ad- and abaxially ± flat; apex rounded-obtuse to slightly pointed; base gradually tapering to insertion on stem; margins entire, reddish-infused. Inflorescence a ± flat-topped, corymbose cyme, (130–)150–300(–350) mm tall, with small, leaf-like bracts at nodes, bracts increasingly smaller upwards, floriferous only at top, erect or leaning, apically sparsely branched, many-flowered, branches opposite, subtended by small, leaf-like bracts, axis light green, reddish higher up; pedicels 3–4(–6) mm long, slender. Flowers 9–10 mm long, erect; calyx dull green, very strongly reddish-infused; sepals 4, 1 × 2–3 mm, ± separate, basally very slightly fused, lanceolate-triangular, acute-tipped, hardly to slightly contrasting against basal part of corolla; corolla 8–9 mm long, enlarged basally around carpels, distinctly and tightly anti-clockwise-twisted apically after anthesis; corolla tube 7–8 mm long, bright crimson red throughout, light green basally at level of sepals, 4-angled, narrowly urceolate, globose basally, narrowing above carpels; corolla lobes 6–7 × 1.5–2.0 mm, strongly recurved or spreading at 90° angle, narrowly lanceolate-falcate, weakly diurnal, uniformly bright crimson red, acutely tapering apically, margins apically slightly in-rolled. Stamens inserted in two distinct ranks, one in middle of corolla tube, one higher up towards mouth of corolla tube, included; filaments 1.0– 1.5 mm long, thin, yellow; anthers 0.25–0.30 mm long, yellow. Pistil consisting of 4 carpels; carpels 3 mm long, uniformly light green; styles 0.75–1.00 mm long, yellowish green; stigmas very slightly capitate, yellowish white; nectar scales 1.5–2.0 mm long, linear, light yellow. Follicles 3–4 mm long, light green at first, enveloped in dry, purplish remains of corolla, eventually brittle, grass spikelet-like with remains of corolla then light brownish white. Seed not observed. Chromosome number: unknown.

Distribution and habitat:—Except for the most general, no locality data from specimens or field observations are given. This deviation from widely followed taxonomic practice is justified by the fact that poaching of succulent plants from the wild in South Africa is a severe and escalating problem, and it was decided not to provide any information regarding the exact whereabouts of this new species that could cause known populations to be targeted for destructive collecting ( Smith et al. 2023b).

At present, K. steyniae is known to definitely occur naturally in the northeastern part of KwaZulu-Natal and further north in Eswatini in the eastern highlands of the country. The elevation at these locations varies between 250–1200 m asl. Kalanchoe steyniae occurs sympatrically with K. rotundifolia but hybrids or transitional forms between these two species are yet to be recorded.

Plants of K. steyniae almost invariably grow in the dappled shade of a range of different grasses, shrubs, and bushveld trees, often on very rocky substrates ( Fig. 3D ), in Zululand Lowveld (SVI 23) and Lebombo Summit Sourveld (SVI 17) within the Savanna Biome ( Rutherford et al. 2006).

The largest diversity of southern African Kalanchoe species is found in eastern southern Africa where 22 of the indigenous subcontinental species occur east of the Drakensberg massif, from south-central KwaZulu-Natal in the south in a broad sweep to the Limpopo River in the north (Smith & Figueiredo 2021: 207–208, Smith 2022b: 164– 167).

Eponymy:— Kalanchoe steyniae is named for Dr Hester Maria Steyn (born in Potgietersrus [now Mokopane] in South Africa’s Limpopo Province, 3 November 1967 –) ( Fig. 3E ). She obtained her B.Sc. [botany and geography (1988)], B.Sc. (Hons) [plant ecology (1990)], M.Sc. [plant ecology (1993)], and Ph.D. [plant taxonomy (2018)] degrees from the University of Pretoria. From 1991 to 1999 she worked in the Department of Botany, University of Pretoria, accepting in 2000 a position in the Data Section of South Africa’s then National Botanical Institute (now the South African National Biodiversity Institute) where she inter alia significantly contributed to the African Plant Checklist and Database, in collaboration with the Conservatoire et Jardin Botanique de la Ville de Genéva, Switzerland. This resulted in the first checklist and database (http://africanplantdatabase.ch) for any continent (Klopper et al. 2006). In 2009 she transferred to Herb. PRE, the National Herbarium of South Africa, Pretoria, where she is still employed as a plant systematist. Hester has a special interest in georeferencing, databasing of specimens, and the floristics of arid areas. She recently co-authored two major works on South African botany (Koekemoer et al. 2013, 2023).

Figures

FIGURE 2. A. Plants of Kalanchoe steyniae are small-growing shrublets that reach reproductive maturity when they are about 200 mm tall. B. Kalanchoe steyniae often develops stilt-like, aerial roots from its stems and branches. Interestingly, with its brittle-woody stems and branches, K. steyniae is considerably more pest resistant than K. rotundifolia, with aphid infestations being very uncommon in K. steyniae. C. The leaves of K. steyniae have a firm texture.As in K. rotundifolia, detached leaves will sprout new plants from the base. D. Flowers of K. steyniae are densely and compactly arranged in ± flat-topped, corymbose cymes. All photographs by Gideon F. Smith.

FIGURE 3. A. Lateral view of flowers of Kalanchoe steyniae (left) and K. rotundifolia (right). Note the much longer, very strongly reddish-infused sepals of K. steyniae. Scale bar = 10 mm. B. Frontal view of the corolla mouth of K. steyniae (left) and K. rotundifolia (right). The uniformly bright crimson red, narrowly lanceolate-falcate corolla lobes of K. steyniae are strongly recurved, as here, or spread at a 90° angle. Scale bar = 10 mm. C. The yellow- to orangey yellow-flowered K. alticola has sepal lobes of 4–7 mm in length. D. Kalanchoe steyniae often occurs on very rocky substrates, as here in Lebombo Summit Sourveld vegetation. E. Hester M. Steyn (1967–) for whom K. steyniae is named. Photographs A–B and D by Gideon F. Smith; photograph C by Neil R. Crouch; and photograph E by Marinda Koekemoer.