Kalanchoe, Adanson, 1763

Shtein, Ronen, Smith, Gideon F. & Ikeda, Jun, 2021, Aspects of the taxonomy of the Kalanchoe daigremontiana species complex (Crassulaceae subfam. Kalanchooideae) and associated interspecific hybrids in southern Madagascar, with the description of a new nothospecies, K. × descoingsii (= K. laetivirens × K. tubiflora), Phytotaxa 524 (4), pp. 235-260 : 249-252

Kalanchoe ×descoingsii Shtein, Gideon F.Sm. & J.Ikeda sp. nov. ( Figs 3 and 4 ).

Type:— MADAGASCAR. Arboretum d’Antsokay , southeastern Madagascar , in a sparse forest floor, collected on 04 October 2018 by Jun Ikeda s.n., R. Shtein 501 (holotype TELA [ TELA935 ]; isotype TELA [ TELA936 ]). Material harvested as the holo- and isotypes was cultivated in Israel ( Figs 3 and 4 ) .

Suggested parentage:— Kalanchoe laetivirens Descoings (1997: 85) × K. tubiflora ( Harvey 1862: 380) Hamet (1912: 44) .

Diagnosis:— Kalanchoe × descoingsii differs from all other representatives of K. subg. Bryophyllum by being lowgrowing for most of its vegetative life span; by its densely foliated, solitary pseudo-rosettes that drastically elongate as flowering approaches; by being constitutively phyllo-bulbiliferous; by its oblong leaves that are apically obtuse to rounded; by having deeply dentate leaf blade margins subducted by recurved, spathulate bulbil-carrying pedestals; by its distal leaves and peduncular leaves gradually transitioning from conspicuously petiolate, deeply auriculate, basally broadened, oblong basal leaves, into being subsessile, attenuate, entire bar the apex, and generally not bulbil-forming; by its peduncle indistinctly transitioning from the distal vegetative part of the stem into the flower-bearing portion of inflorescence; by the corolla that is somewhat pinkish to whitish green when emerging, to being predominantly vibrant pink to orange-pink at anthesis; by the free sepal segments being longer than wide, ovate-deltoid, and about as long as to somewhat longer than the fused portion; by the calyx tube being wider than long; and by having nectar scales that are about as wide as long, spreading, and rounded-notched at the apex.

Description:— Plants multi-annual, entirely glabrous, non-glaucescent throughout, unbranched, erect, often basally decumbent, about 0.8–1.2 m tall when in flower. Stem mostly herbaceous, lenticular, cylindrical; lower portion 25–35 cm long, 10–13 mm in diam., dense, green to pinkish brown; upper portion 50–80 cm long, 5–8 mm in diam., extremely sparse, purple; leaf scars narrowly crescentiform, conspicuous, slightly protruding, not connate; internodes 0.7–1.5 cm long basally, 4.5–6.0 cm long in distal half, distinctly lighter green to pink. Leaves opposite, decussate, succulent; basal leaves distinctly petiolate, densely arranged, wilting by anthesis; petiole 3.0– 5.5 cm long, 4–6 mm in diam. medially, up to 6–8 mm in diam. at base, subcylindrical, often slightly concave above and convex below, slightly widened around stem, green to purple, distinctly maculate with large dark brown or dark purple blotches; blade 8–12 cm long, 3.5–5.8 cm wide at base, 2.0– 3.5 cm wide elsewhere, adaxially green to green-brown, sometimes ornate with purple veining patterns centrally and basally, minutely dark-maculate, abaxially yellowish grey, strongly striped in dark brown or dark purple, narrowly elliptic to oblong, sometimes basally obtusely trilobate, widened distinctly in basal <⅓, widest at basal ¼, strongly guttered lengthwise, concave above and convex below; margins green-grey to reddish pink, regularly dentate, darkly blotched between dentations, below blotches marked by pale organogenic and/or embryogenic notches, later developing pedestals; dentations 2.0–5.5 × 3–6 mm, acute, broad, increasing in acuity basally and apically; bulbil production fully constitutive, occurs on dedicated pedestals, at least on apical ½ of each leaf blade margin or on its entirety; bulbils large, bearing 3–5 leaf pairs and sometimes their own bulbils while still attached to mother plant, almost round leafed, minutely maculate; pedestals 2.0–5.5 × ± 1.5 mm, spathulate, bent to abaxial blade surface, incurved apically; base strongly auriculate, extending up to 17 mm behind petiole-blade connection, often ornate with two erect, dentate, bulbiliferous auricles; apex obtuse to rounded; apical leaves petiolate to subsessile; petiole 1.5–2.5 cm long; blade 5.0–7.5 × 0.8–1.2 cm, equally wide throughout to widest apically, narrowly elliptic-oblanceolate, mostly entire, few-dentate apically, not pedestalate, apically bluntly obtuse to rounded, basally minutely auriculate-cuneate to attenuate. Inflorescence a compact, many-flowered, capitate thyrse, lacking leaves or barely leafed at anthesis, non-bulbiliferous, i.e., dense bulbil clusters do not develop, but a few, large, discrete plantlets may form post-flowering, dense, terminal, 7.5–15.0 cm wide, consisting of 5–7 short dichasial cymes, each 5–9 cm long; peduncle 14–21 cm long, 4–6 mm in diam., single, cylindrical, indistinctly transitioning from distal vegetative part of stem into flower-bearing portion of inflorescence; bracts 3–5 × ± 1 cm, sessile, attenuate, narrowly oblong, mostly entire, few-dentate and bluntly obtuse apically, wilting soon; floral bracts ± 2 × ± 1 cm, bract-like, wilting soon; pedicels 12–18(–25) mm long, curved, cylindrical, tapering towards flowers from 1.2–1.4 mm to ± 0.60–0.75 mm in diam., purple. Flowers numerous, pendent, campanulate. Calyx 12–15 × 7–8 mm, light or grey-green to purple, dark purple-spotted where free sepal segments fuse, succulent, thick, campanulate-urceolate, rounded, basally ± flat, widest in middle of tube, then gradually constricted upwards; tube 5.5–6.5 mm long; free sepal segments 6.5–8.0 mm long, widest at base at ± 5 mm, ovate-deltoid, very acute, apiculate, adpressed to corolla to slightly spreading. Corolla 30–33 mm long, vibrant pink to orange-pink, whitish green when emerging and where obscured by calyx, non-stipitate; tube 22–24 mm long, especially basally ± 4-angled, basally adpressed around and above carpels, up to 5.5 mm wide, then diminishing to ± 4 mm wide at its thinnest, then gradually inflating to base of petals where it is generally widest at a width of 7–8 mm; lobes 8.0–9.5 × 6–7 mm [at base], widest at 8–9 mm at ⅓ from tip, broadly obovate, apically rounded, very slightly apiculate, somewhat spreading. Stamens 8, inserted low down in corolla tube, at ± level of carpels, slightly exserted, visible between, and reaching apex of petals; filaments of two similar lengths, fused basally, then adpressed, protruding inside base of corolla, free higher up for ± 20–22 mm, thin, yellow-green basally and apically, strongly infused with purple-pink elsewhere; anthers ± 1.0–1.2 × 0.8 mm, dark grey, producing yellow pollen, ovate-cordate, somewhat longer than wide. Pistil consisting of 4 carpels; carpels ± 7–8 × 1.7–2.0 mm, convergent, fused basally, free above, uniformly dark green, conical lanceolate, widest in lower ⅓, cuneate towards styles; styles ± 15–17 mm long, uniformly yellowish green; stigmas very minutely capitate, dark green; scales ± 1.5–2.0 × 1.5–2.0 mm, yellow-green, free, spreading, rounded-square, about as wide as long, thickened especially basally, incurved, upper corners rounded, emarginate. Follicles not seen. Seeds not seen. Chromosome number: 2 n = unknown.

Eponymy:— Kalanchoe ×descoingsii commemorates Bernard Marie Descoings (born Paris, France, 7 September 1931 –died Largentière, Ardèche, France, 23 October 2018) ( Madin 2018). He studied agronomy at Montpellier and in 1953 graduated as an agricultural engineer. From 1953 to 1954 he completed a training course at the Phanerogam Laboratory of the Muséum national d’Histoire naturelle, in Paris, where, under the guidance of Jean Henri Humbert, he developed an interest in tropical botany. Descoings ( Fig. 12 ) subsequently spent time in Madagascar (1954–1958) and after having been recruited by the ‘Office de la Recherche Scientifique et Technique Outre-Mer’ (ORSTOM), spent four years in the Congo, where he directed ORSTOM’s Botanical Laboratory from March 1960 to 1965. Between 1965 and 1985 Descoings was variously based in Montpellier, French Guiana, and Burkina Faso, and from 1970 until his retirement in 1995 he additionally held various positions in Montpellier, France. In 1976 he defended his doctoral dissertation, ‘Approche des formations herbeuses tropicales par la structure de la végétation’, in Natural Sciences in the Faculty of Sciences of the University of Montpellier. While Descoings was based at the Paris Herbarium as a young man, the exposure he had to Jean Henri Humbert likely sparked his interest in Kalanchoe , as Humbert himself had more than a passing interest in the genus ( Humbert 1933a, b). From the late 1990s to mid-2000s, Descoings described 16 new species and nothospecies in the genus from Madagascar, including K. laetivirens and K. sanctula , both reviewed in this paper. In 2003 Descoings treated Kalanchoe in the Crassulaceae volume of the Illustrated Handbook of Succulent Plants project ( Eggli 2003), which in several respects does not coincide taxonomically with the earlier treatment of Boiteau & Allorge-Boiteau (1995) of the genus as found in Madagascar. In 2005, Descoings paid special attention to the nothospecies of southern Madagascar, being the first to recognise their relatively common occurrence ( Descoings 2005a). A year later he published an infrageneric classification that proposed the recognition of a morphologically diverse K. subg. Calophygia Descoings (2006: 24) , but not K. subg. Kitchingia, a view with which we do not agree. Smith (2019) was dedicated to Descoings.

Distribution:—Southern Madagascar, Arboretum d’Antsokay ( Fig. 9 ). Mr Andry Petignat, Hermann Petignat’s son, an author and the current owner of the Arboretum d’Antsokay informed us that K. × descoingsii was not imported to his garden and therefore most likely spontaneously arose there. He further noted the similarities this plant bears to K. laetivirens , especially in habit and colouration, and that it rarely flowers, remaining rather short, though it has successfully spread in the garden, presumably vegetatively.

Kalanchoe tubiflora and K. laetivirens , the parents of K. × descoingsii, are not known to grow sympatrically in the natural distribution range of K. laetivirens (discussed above in detail). In cultivation and in the Arboretum d’Antsokay, K. × descoingsii is able to rapidly reach its bulbil producing phase and spreads easily at a rate on par with that of K. × houghtonii. Detached bulbils may start bulbil production on their fourth leaf pair, or even carry bulbils of their own while still attached to the mother plant. Kalanchoe × descoingsii therefore poses a high invasiveness potential.

Figures

FIGURE 3. Habit and inflorescences of Kalanchoe ×descoingsii (R. Shtein 501). A. Apical view of plant in bud, showing the green, small-sized, succulent, acute-tipped flower buds. B. Lateral view of plant showing the unusual phenological transition in leaf shape and node spacing, and the indistinct stem-peduncle transition. C. Leaves in the apical ¼ of the stem; the leaves are dark purple-coloured, well-spaced, attenuate, oblanceolate, and the margins subentire, except apically. D. Basal portion of the stem, showing extremely short nodes and densely arranged, conspicuous leaf scars. The striped and distinctly auriculate base of the leaf blade in side view, with bulbils and bulbil pedestals visible. E. Detail of the flower-bearing portion of the inflorescence at early anthesis, showing the purple-tanned buds and pink corollas that are whitish green when emerging. F. Close-up of the fairly short dichasial cyme, and pink flowers. G. Details of the internally medially orange and apically pink corolla, the yellow pollen, the cuneate carpels dressed with short, rounded nectar scales, and the rounded calyx. Photographs: Ronen Shtein.

FIGURE 4. Phenological transitions in the leaves of Kalanchoe ×descoingsii (R. Shtein 501). A. Transition from the distal, attenuate, oblanceolate leaves, to the medial, auriculate oblong leaves. B. Medial leaves showing the pink, distinctly blotched petiole, pink margins, and central veining pattern, minute adaxial maculation, and the overall bright light green leaf colour. The leaf blade is oblong, roundtipped, minutely auriculate at the base, strongly dentate, and well-developed bulbil pedestals with abscission scars can be seen in the apical ½. C. Medial leaves showing the round-obtuse apex, oblong leaf blade shape, and colouration. D. Leaf in the basal ¼ of the stem, close to wilting and abaxially striped, showing spathulate pedestals subducting large denticules all around the leaf blade margin with a few bulbils still attached, a deeply auriculate leaf blade base, as well as a similar colouration as in F, but with the blade overall a darker olive green. E–F. Comparative view of the K. tubiflora-like bulbils that are still attached to a leaf, and rooted bulbils with the appearance of those of K. laetivirens. F. Basal, obtuse-tipped leaf with darker colouration, a generally oblong leaf blade shape, but showing the characteristic widened and auriculate base.The dark colouration and below-the-leaf position of the still-attached bulbils is notable, compared to the light green, K. laetivirens-like bulbils in the background. Each bulbil is attached to a dedicated pedestal (obscured from view by the leaf blade margins). Photographs: Ronen Shtein.

FIGURE 9.All documented occurrences of representatives of the Kalanchoe daigremontiana species complex, and associated interspecific hybrids, in southern Madagascar. The precise locality of the type of K. tubiflora in Madagascar is insufficiently known to be placed (see Figueiredo & Smith 2017: 771). Overlapping markers are separated using Point Displacement in QGIS, except of the marker of the locality of the neotype of K. sanctula which is overlapped by the marker of the type of the name and is not displayed. © OpenStreetMap contributors. Locality information is included in the Supplementary file.

FIGURE 12. A. Bernard Marie Descoings (1931–2018), when visiting Mr Jean-Luc Billouet’s succulent collection inApril 2012.B. When aloe specialist Dr (h.c.) Gilbert W. Reynolds, visited Madagascar in the 1950s, Descoings, then a young man in his mid-20s, accompanied and assisted him (Reynolds 1958: 6–7, 146, Fig. 100, Reynolds 1966: ix, 515, Fig. 543). Descoings here stands next to a large specimen of Aloestrela suzannae (Decary 1921: 26) Molteno & Gideon F.Sm. in Smith & Molteno (2019:5). The original of the black-and-white image was likely held in Herb. PRE along with parts of the archives of Reynolds, but is apparently no longer extant. Photographs: A, Jean-Luc Billouet; B, unknown; likely G.W. Reynolds.