Kalanchoe × sogae Gideon F.Sm. & Figueiredo, 2022

Smith, Gideon F. & Figueiredo, Estrela, 2022, Kalanchoe × sogae (Crassulaceae subfam. Kalanchooideae) derived from Kalanchoe lateritia × K. sexangularis, with notes on the inheritance of hairiness and resistance against phytophagous insects in Kalanchoe hybrids, Phytotaxa 572 (1), pp. 97-106 : 99-102

Kalanchoe × sogae Gideon F.Sm. & Figueiredo , nothospec. nov. ( Fig. 2A–F )

Type:— SOUTH AFRICA. Gauteng province —2528 (Pretoria): Tshwane , (– CA), ex hort., 28 June 2022, G. F. Smith 1185 (holotype PRU) .

Parentage:— Kalanchoe lateritia Engler (1894: 19) × Kalanchoe sexangularis Brown (1913: 120) .

Diagnosis:—Like one of its parents, K. sexangularis , K. × sogae has strongly red-infused leaves, so differing from the other parent, K. lateritia , which has light green to yellowish or brownish green leaves. Kalanchoe sexangularis is completely glabrous, while K. lateritia has a pubescent vestiture; K. × sogae is puberulous and intermediate between its two parents. In K. × sogae the sepals are prominent and ± as long as those of K. lateritia , while the sepals of K. sexangularis are very small. The corolla tube of K. lateritia is light green and orangey yellow-infused, that of K. sexangularis is uniformly yellowish green, while that of K. × sogae is light green with strongly orange-infused angular sections. The corolla lobes of K. × sogae are obovate to nearly round while those of K. lateritia are obovate to lanceolate-obovate and those of K. sexangularis are ovate to subcircular.

Description:—Perennial through sprouting from the base, but individual rosettes annual or biennial, dying after flowering, rather few-leaved, unbranched, puberulous throughout, succulent, to 0.5–1.0 m tall when in flower. Stems one to several, erect or leaning, light to intensely dark red, densely puberulous above, reddish brown, less puberulous lower down especially where leaves shed, often ± leafless at fruiting, round in cross-section throughout, leaf scars obvious, white. Leaves decussate, petiolate, light to intensely dark red, succulent, spoon-like longitudinally folded upwards, erectly-spreading to spreading to often floppy, caducous when inflorescence develops, somewhat papery when dry, densely puberulous throughout, hairs whitish or very light brownish white; petiole 10–20 mm long, slightly grooved above, puberulous, somewhat stem-clasping; blade (50–)60–90(–100) × 30–50 mm, elongated-elliptic to ovate to ovate-spathulate; base attenuate to cuneate; apex obtuse, round, not indented, rarely somewhat acute; margins variably crenate or dentate in upper ¾–⅞, entire towards petiole. Inflorescence consisting of contracted cymes forming dense corymbs, 0.30–0.75 m tall, terminal, erect, many- and apically dense-flowered, generally rounded, sometimes flat-topped, branches opposite, growing upwards at a ± 30º angle, subtended by small leaf-like bracts, small leafy shoots in axils usually absent, puberulous throughout; peduncle light green to strongly red-infused; pedicels 1–2 mm long, stout. Flowers 17–18 mm long, erect to slanted sideways, never pendent, bright orange-red in bud apically, conspicuously to densely puberulous throughout except adaxial corolla lobe surface; calyx consisting of 4 sepals, prominent, light green, strongly orange-infused throughout, slightly fleshy; sepals 7–9 × 2.0– 2.5 mm, basally fused into a short tube 1.0– 1.5 mm long, separate above, narrowly triangular-lanceolate, acute, ± clasping the corolla, obscuring and contrasting against light green, swollen portion of corolla tube where covered by calyx, drying reddish brown; corolla (16–) 17–18 mm long, distinctly enlarged basally, slightly twisted apically after anthesis; tube (15–) 16– 17 mm long, light green especially basal swollen part, distinctly 4-angled-fluted, rounded when viewed from below, gradually narrowly cylindrical apically, angles distinctly and strongly orange-infused to yield striped appearance; lobes 5–6 × 4–5 mm, bright yellow to strongly bright orange-infused towards margins and apical ⅓, obovate to nearly round, gradually acuminate towards apex, apiculate-mucronate. Stamens 8, inserted in ± two ranks at about the middle of the corolla tube, well included; filaments 2.5–3.0 mm long, thin, flimsy, light yellow; anthers 0.5–1.0 mm long, yellowish grey, oval to oblong. Pistil consisting of 4 carpels; carpels 5–6 mm long, light green; styles 1–2 mm long; stigmas very slightly capitate, whitish; scales (2.0–)2.5(–3.0) mm long, linear to linear-ribbon-like to very slightly linear to oblong to tapering to apex, yellowish green. Follicles not seen. Seeds not seen. Chromosome number: unknown.

Eponymy:— Kalanchoe × sogae is named for Dr Jotello Festiri Soga (born near Stutterheim, Eastern Cape province, South Africa, 1865–died Amalinda near East London, Eastern Cape province, South Africa, 6 December 1906), the first South African to have qualified as a veterinary surgeon. He studied in Scotland and thereafter worked for the then Cape Department of Agriculture ( Hammel 2020: 54). He had an interest in ethnobotany and is known to have liaised with his botanical contemporaries Peter MacOwan and Andrew Smith ( Gunn & Codd 1981: 327, Figueiredo & Smith 2021: 291–292). He inter alia studied krimpsiekte, also called nenta poisoning, a chronic form of heart glycoside poisoning, especially among small livestock ( Soga 1891). Krimpsiekte is caused by a range of representatives of the Crassulaceae , including by kalanchoes ( Smith et al. 2019a: 43, 52, 108), with nentabos being one of the Afrikaans vernacular names of K. rotundifolia ( Haworth 1824: 188) Haworth (1825: 31) .

Flowering time:— Kalanchoe ×sogae flowers mainly in the mid-winter months, June to August in the southern hemisphere.

Notes:—Several biennial, multiannual, and perennial species of Kalanchoe are variously and virtually throughout pubescent or tomentose, or are squamulose (finely scale-like covered). This applies especially to the medium-sized to large shrubs and small trees with woody stems that are included in the ‘woody clade’ of K. subg. Kalanchoe that is naturally restricted to Madagascar (see for example Smith et al. 2021c, d and Smith & Figueiredo 2019, 2022a, b, 2023b).

Species that have most of the external surfaces of their organs so adorned include the widely cultivated K. beharensis Drake del Castillo (1903: 41) (see Smith et al. 2021d), K. millotii Hamet & Perrier de la Bâthie (1912: 374) (see Smith & Figueiredo 2019, Smith et al. 2019b, Smith 2020 f, and Smith et al. 2021e), and K. tomentosa Baker (1882: 110) (see Smith 2020g). Similarly, nothospecies of which these species are variously the parents, for example K. × edwardii Smith & Shtein (2020: 120) [ K. beharensis × K. tomentosa ] (see Smith 2022d); K. × gildenhuysii Smith & Figueiredo (2020: 43) [ K. millotii × K. tomentosa ]; and K. × hummeliae Smith (2020f: 91) [ K. beharensis × K. millotii ] (see Smith 2022d: 155), are variously hairy. Therefore, where two variously pubescent- or tomentose-leaved species hybridise, the offspring is invariably hairy to varying degrees. The opposite also holds true: where two glabrous Kalanchoe species are hybridised, the offspring is glabrous (see K. × gunniae Gideon F.Sm. & Figueiredo in Smith et al. 2019c: 147).

A hairy vestiture is not restricted to some Malagasy Kalanchoe species; species from Africa and other parts of the distribution range of the genus also show this trait [see for example Smith et al. 2019a: 170–176 with reference to K. lanceolata ( Forsskål 1775: CXI & 89) Persoon (1805: 446), where onset of the reproductive phase yields hairy peduncles, bract-like leaves, and flowers].

Further, a hairy vestiture is not restricted to the vegetative parts of these, and some other, species of Kalanchoe ; in many instances the stem-peduncle continuum, inflorescence branches, and flowers (usually excepting the adaxial corolla lobe surface) too can be variously and often very densely hairy ( Weryzko-Chmielewska & Chernetskyy 2005).

Horticultural material of the intensely red-infused K. sexangularis , an endemic southern and south-tropical African species, has for long been popular in outdoor cultivation in mild-climate regions of the world. This species has also been combined with reddish purple-leaved forms of K. luciae to yield horticulturally successful, strikingly red- to purplish red-leaved material that was described as K. × estrelae , as well as giving rise to orange-leaved material described as K. × leistneri Smith (2021c: 250), following combination with K. winteri Gideon F.Sm., N.R.Crouch & Mich.Walters in Crouch et al. (2016: 219).

Kalanchoe sexangularis , as well as K. × estrelae , can act as hosts of, and are sometimes severely attacked by, the kalanchoe weevil, Sternuchopsis sedi ( Marshall 1938) ( Coleoptera : Curculionidae : Molytinae : Mecysolobini ) ( Fig. 3A–B ). The weevil deposits its eggs in the stems where the hatched larvae feed on the internal tissues, usually leaving only a hollowed out and very much weakened and tube-like stem that will easily snap off. The weevil can also incite stem galls and both larvae and adults can cause substantial damage to kalanchoe populations. However, to date, likely given its puberulous vestiture, K. × sogae has not been observed as acting as a host of S. sedi . It has been long-known that variously hairy representatives of the Crassulaceae are less prone to attacks by phytophagous insects than glabrous species [see for example Smith et al. 2019a: 80 on the hairy form of Cotyledon barbeyi Schweinf. ex Baker (1893: 624) ].

Kalanchoe × sogae responds well to cultivation and once material propagated through stem cuttings is rooted very little aftercare is required. With red, yellow, and orange, the predominant leaf and flower colours of K. × sogae , which are so-called related colours on the landscaping colour wheel ( Calhoun 2009: 118), this nothospecies, material of which has thus far entered the horticultural trade in limited volumes, is an excellent addition to material suitable for waterwise, even no-irrigation, gardening in mild climates ( Smith 2020a –d, 2021a, Smith & Hankey 2021, Smith & Shtein 2021).

Figures

FIGURE 2. Kalanchoe ×sogae. A. At flowering maturity plants of this shrubby nothospecies reach a height 0.5–1.0 m. B. Leaves are puberulous and mid-green to most often distinctly red or strongly crimson red-infused. C. Apart from being intensely reddish-infused, virtually all the plant parts are puberulous. In bud, the flowers are bright orange-red apically. Flowers are borne erectly to slanted sideways—never pendent. Excepting the adaxial surface of the corolla lobes, the flowers, too, are conspicuously puberulous throughout. D. Especially the basal swollen part of the corolla tube is light green and distinctly 4-angled-fluted. E. Flowers, here in lateral view, of K. ×sogae (centre) are intermediate between those of K. lateritia (left, one of the parents of K. ×sogae) and K. sexangularis (right, the other parent of K. ×sogae); rounded when viewed from below; gradually narrowly cylindrical above; and with the angles distinctly and strongly orange-infused to yield a green-orange-striped appearance. F. Corolla lobes of K. ×sogae (centre) are bright yellow to strongly bright orange-infused, rather similar to those of K. lateritia (left) but differs from the bright yellow, faintly brown-tipped ones of K. sexangularis (right). All photographs taken by Gideon F. Smith.

FIGURE 3. A. The indigenous South African weevil Sternuchopsis sedi (Coleoptera: Curculionidae: Molytinae: Mecysolobini) on a leaf of K. sexangularis. The weevil is 7 mm long. B. The weevil deposits its eggs in the stems of kalanchoes where the hatched larvae feed on the internal tissues, usually leaving only a hollowed out and very much weakened tube that will easily snap off. Both photographs taken by Gideon F. Smith.