Kalanchoe delagoensis, Ecklon & Zeyher, 1837

Smith, Gideon F., 2024, The name to be used for the most invasive species of Kalanchoe globally finally resolved: nomenclature and taxonomy of the Malagasy Kalanchoe delagoensis (Crassulaceae subfam. Cotyledonoideae), Phytotaxa 672 (3), pp. 225-241 : 231-237

Nomenclature of Kalanchoe delagoensis

Kalanchoe delagoensis Ecklon & Zeyher (1837: 305) ( Figs 1–9 ).

Type:—[ MOZAMBIQUE or, possibly, MADAGASCAR]. s.l. s.d., s.c. / leg. ign. s.n. [likely William Fitz William Owen s.n. or possibly John Forbes s.n.] (holotype S S-G-10717, https://herbarium.nrm.se/specimens/S-G-10717/image/).

Homotypic synonyms:— Bryophyllum tubiflorum Harvey (1862: 380) , nom. illeg. ( Turland et al. 2018: Art. 52.1).

Bryophyllum delagoense (Eckl. & Zeyh.) Schinz in Schinz & Junod (1900: 38).

Kalanchoe tubiflora (Harv.) Hamet (1912: 44) , nom. illeg. ( Turland et al. 2018: Art. 52.1).

Isonym with no nomenclatural standing:— Bryophyllum delagoensum [sic] (Eckl. & Zeyh.) Druce (1917: 611).

Heterotypic synonyms:— Kalanchoe verticillata Scott Elliot (1891: 14) . Type:— MADAGASCAR. “Fort Dauphin, open sandy dunes near sea”, G.F. Scott Elliot 2983 (lectotype, Herb. K barcode K000232791), image of the specimen accessible at https://plants.jstor.org/ stable/10.5555/al.ap.specimen.k000232791, here designated as lectotype. Isolectotype:—[ MADAGASCAR.] “Fort Dauphin, open sandy dunes nr [near] sea, [collected] June July [presumably 1890] recd 9/90 [received, presumably at Herb. K, in September 1890]”, G.F. Scott Elliot 2983 (Herb. K barcode K000232792), image of the specimen accessible at https://plants.jstor.org/stable/10.5555/ al.ap.specimen.k000232792.

Bryophyllum verticillatum (Scott Elliot) Berger (1930: 411) . Type:—as for K. verticillata .

Geaya purpurea Costantin & Poisson (1908: 636) . Type:— MADAGASCAR. Nord du cap Sainte-Marie, [M.F.] Geay 6372 (lectotype, as “Holo-P” according to Boiteau & Allorge-Boiteau (1995: 90), Herb. P barcode P00374200), image of the specimen accessible at http:// coldb.mnhn.fr/catalognumber/mnhn/p/p00374200, corrected to lectotype by Smith (2024: 245–247). Other specimens examined:— [ MADAGASCAR.] Plateau, au nord du cap Sainte-Marie; [M.F.] Geay 6335 (Herb. P barcode P00444108); [ MADAGASCAR.] Nord du faux cap, [M.F.] Geay 6336 (Herb. P barcode P00444109).

Notes on the holotype of the name Kalanchoe delagoensis :—In the protologue of the basionym of this species, Harvey (1862: 380) cited a single collection, treated as having been made by John Forbes, in Delagoa Bay, i.e., the area around Maputo [Bay] in southern Mozambique. Harvey (1862) added that the collection was kept in the Sonder Herbarium, i.e., the Herbarium of Otto Wilhelm Sonder (1812–1881). Herb. S had acquired the major part of the South African herbarium of Sonder ( Gunn & Codd 1981: 329, 387). The specimen cited by Ecklon & Zeyher (1837: 305) and by Harvey (1862: 380) is kept at Herb. S (S-G-10717), it consists of two flowers and a stem fragment and it has no label information. The plant could have originated from Madagascar, where K. delagoensis occurs naturally and where Owen’s expedition is known to have called (see Figueiredo & Smith 2022a), and could have been collected by either Owen (likely) or by Forbes (possibly).

However, there is a chance that this species, which has well-known and considerable invasive tendencies (Smith et al. 2019: 112–114, 274–278, 2021: 9, 11), could already have become naturalised in Mozambique by then. Even in Madagascar, its country of origin, K. delagoensis seems to have been spreading (see Shtein et al. 2021: 250, Figure 9 ). The two collectors on the Owen expedition, Forbes and Hilsenberg, are known to have visited Madagascar, and Owen also joined collecting excursions on the island (see for example Owen 1833 [vol. 2]: 33). However, Owen was not listed as a collector in Madagascar by Dorr (1997).

Nomenclatural notes on the type of the name Kalanchoe verticillata :—When describing K. verticillata , the only material that Scott Elliot (1891: 15) cited was “Sandy dunes, Fort Dauphin, [G.F. Scott Elliot] 2983!” At least two specimens that were both collected by Scott Elliot under his collecting number “ 2983 ” exist at Herb. K.

These two specimens —both of them syntypes (see Turland et al. 2018: Art. 9.6 and Note 1 under Art. 40)—were mounted on two different sheets. These specimens can be identified as follows with reference to the red-printed labels headed “EX. HERB. G.F. SCOTT ELLIOT” and “No.” that are attached to them:

1. “2983” that was completed by hand after “No.” and with the text on the label, in ink stating: “ Madagascar. Kalanchoe verticillata sp. Open sandy dunes near sea. Fort Dauphin.” This syntype is here designated as lectotype, Herb. K barcode K000232791 ; image of specimen accessible at https://plants.jstor.org/stable/10.5555/al.ap.specimen. k000232791. [ The preserved material is of two, straight, flowering specimens with leaves attached lower down on both peduncles. A paper capsule apparently containing flower fragments, and on which notes were written in pencil, is attached to the specimen.]

2. “2983” that was completed by hand after “No.” and with the text on the label, in ink stating: “Recd 9/90 [Received September 1890] Madagascar. Kalanchoe verticillata . Open sandy dunes nr [near] sea. Fort Dauphin. June July”. This syntype becomes an isolectotype, Herb. K barcode K000232792 ; image of specimen accessible at https://plants.jstor. org/stable/10.5555/al.ap.specimen.k000232792. [The preserved material is of two, bent, flowering specimens with leaves attached lower down on the peduncle on the left, and with the peduncle on the right devoid of leaves.]

The two accessions, “1.” and “2.”, above, were both clearly given the number “G.F. Scott Elliot 2983” and both qualify as original material because they were obviously collected by and available to Scott Elliot before he published the name K. verticillata in 1891.

Of these two specimens the G.F. Scott Elliot 2983 specimen—the more complete one—that can be identified as Herb. K barcode K000232791 is designated as the lectotype of the name K. verticillata .

Description of Kalanchoe delagoensis :—Biennial or, rarely, multi-annual, erect to leaning to procumbent, glabrous, brittle, succulent shrubs, to 2 m tall; unbranched or very rarely sparsely branched or suckering near base, with canopies terminating in an inflorescence. Stems generally weak, thin, 6–12(–15) in diam., light yellowish brown to yellowish grey to brownish grey, usually erect or toppling over under weight of inflorescence. Leaves many, tricussate, sparsely arranged, generally evenly spaced throughout, slanted away from branches at ± 45°, succulent, glabrous, sessile, terete, cylindrical to very narrowly oblong, often grooved above, bluish to purplish to brownish green to grey-green with irregular dark green or bluish-purple mottling, somewhat waxy; petiole absent; blade 3–12 cm × 2–5 mm; base slightly narrowed; apex with 2–9 small, conical teeth, usually with bulbils borne on short pedestals, also once leaves are detached. Inflorescence a terminal, apically branched, many-flowered, head-shaped to rounded thyrse, up to 20 cm in diam., erect, peduncle short, straight, non-flori-bulbiliferous until post-anthesis; pedicels 6–12 mm long, glabrous. Flowers tetramerous, pendent, glabrous, waxy bloom ± absent, subtended by small bracts that soon shrivel, corolla much exceeding calyx at anthesis, buds yellowish, papery when dry, drying purplish brown; calyx shorter than corolla, very slightly balloon-like inflated; sepals 10–11 mm long, fused for ± 3–4 mm, free portion elongated-triangular, acute- tippEd, ObsCuriNg LOwEr ± ⅓ Of COrOLLA tubE, LigHt grEENisH rEd, rEd-iNfusiON mOrE prOmiNENt tOwArds tip, rEd ArrANgEd in feint longitudinal lines, creamy to purplish when young; corolla tube 25–30 mm long, various shades of red, from crimson to deep orange to yellowish orange, basally longitudinally infused with yellow along tube angles, campanulate, flaring basally or basally as well as at level of ovaries, constricted at level of ovaries, bulging in middle, slightly flared towards mouth; corolla lobes ± 7–13 × 5–8 mm, subcircular to obovate, apically obtuse-rounded, minutely apiculate. Stamens inserted very low-down in corolla tube at ± same level as carpels, included to hardly exserted; filaments 25–28 mm long, thin, light greenish red, basally light green; anthers ± 1 visible at mouth; pollen greyish yellow. Pistil consisting of 4 carpels; carpels 5–8 mm long, light shiny green; styles 20–25 mm long; stigmas very slightly capitate, green, at first inserted, later hardly exserted; scales ± rectangular-rounded to square, free, ± 0.5 × 1.0(–2) mm, rounded to flat to slightly indented above. Follicles not recorded. Seeds not recorded. Chromosome number: 2 n = 68 [tetraploid] (Smith 2022b: 159, 171–173).

Cultivars described in Kalanchoe delagoensis :— Kalanchoe delagoensis Ecklon & Zeyher (1837: 305) ‘Morvedre’ D.Guillot, E.Laguna, López-Pujol & C.Puche in Guillot Ortiz et al. (2015: 64). Cultivated and escaped in the Iberian Peninsula.

Kalanchoe delagoensis Ecklon & Zeyher (1837: 305) ‘Spirit of 28’ Shaw (2008: 20). Cultivated in the U.S.A.

Kalanchoe delagoensis Ecklon & Zeyher (1837: 305) ‘Ihosy Purple’ Shaw (2008: 20). Cultivated in the U.S.A.

Notes on invasions biology:— Kalanchoe delagoensis is a popular windowsill plant in places with a harsh climate (see for example Kleiner 1981) and in mild-climate parts of the world this species has become widely naturalised, most likely after having escaped from cultivation (see for example Smith 2023 [Africa], Figueiredo & Smith 2009: 74, 2022b: 158 [ Angola], Batianoff & Butler 2002, Witt 2004, and Witt et al. 2004 [ Australia], Otto & Verloove 2016: 14 [Canary Islands], Wang et al. 2016 [ China], Guerra-García et al. 2015 [ Mexico], Silva et al. 2015: 77 [continental Portugal], Tölken 1985: 73–74 and Walters et al. 2011: 237 [ South Africa], and Ward 2008 [ U.S.A.]) ( Figs 8 and 9 ).

Kalanchoe delagoensis is one parent of K. × houghtonii Ward (2006: 94) ( Figs 10–12 ), which has also become well-established as an invasive taxon in mild-climates globally ( Guillot Ortiz 2008: 129, Smith et al. 2015: 97, Smith 2019: 80–81, Herrando-Moraira et al. 2020, Sakhraoui et al. 2024: 153–155). The other parent of K. × houghtonii is K. daigremontiana Raymond-Hamet & Perrier de la Bâthie (1914: 128) that also tends to become weedy and invasive (see for example Smith & Figueiredo 2023: 57, 63–64).

Some variants of the nothospecies K. × houghtonii , such as K. × houghtonii ‘Garbí’ D.Guillot, E.Laguna, López-Pujol, L.Sáez & C.Puche in Guillot Ortiz et al. (2014: 105–106) from the Iberian Peninsula, have been given cultivar names (other cultivars of K. × houghtonii are discussed in Shaw 2008: 22–24 and Guillot Ortiz et al. 2014: 104–105; and Shtein et al. 2021: 237–244 provide information on four different morphotypes [A–D], as well as on variants described as cultivars in this nothospecies).

Figures

FIGURE 1. The thin, erect to somewhat climbing to leaning to procumbent stems of Kalanchoe delagoensis can reach a height of about 2 m, but sometimes remain much shorter. Photograph: Gideon F. Smith.

FIGURE 2. A stand of Kalanchoe delagoensis near Kariega in the Eastern Cape province of South Africa. Photograph: Gideon F. Smith.

FIGURE 3. The terete, narrowly cylindrical leaves of Kalanchoe delagoensis are borne in whorls of three rather than being decussately arranged, which is the common condition in Kalanchoe. Photograph: Gideon F. Smith.

FIGURE 4. A red-flowered variant of Kalanchoe delagoensis. The flowers are arranged in dense, striking head-shaped inflorescences. Photograph: Gideon F. Smith.

FIGURE 5. Colour and size variation in the corollas of six clones of Kalanchoe delagoensis. The flowers are narrowed lower down, so giving them a campanulate appearance. Photograph: Gideon F. Smith.

FIGURE 6. The corolla lobes of Kalanchoe delagoensis are subcircular to obovate, apically obtuse-rounded, and minutely apiculate. Photograph: Gideon F. Smith.

FIGURE 7. In the case of Kalanchoe delagoensis the leaf blade margin has been reduced to the tip of the leaf. The leaves are narrow, cylindrical, and carry numerous small, perfectly formed bulbils towards the leaf apices. These bulbils will root easily on any suitable substrate. Photograph: Gideon F. Smith.

FIGURE 8. A naturalised stand of Kalanchoe delagoensis on a granite outcrop in northwestern Eswatini in eastern southern Africa, about 12 km north of Piggs Peak. Photograph: Gideon F. Smith.

FIGURE 9. Kalanchoe delagoensis naturalised in east-central Mpumalanga province of South Africa. Photograph: Gideon F. Smith.

FIGURE 10. In most vegetative and reproductive morphological respects Kalanchoe ×houghtonii ‘Garbí’ is intermediate between its two parents, K. daigremontiana and K. delagoensis. Photograph: Gideon F. Smith.

FIGURE 11. The flowers of Kalanchoe ×houghtonii ‘Garbí’ are dull light pinkish purple to reddish purple, and longitudinally faintly infused with yellow in the centre of the petals. Photograph: Gideon F. Smith.

FIGURE 12. Comparative morphology (colour, shape, and size) of the flowers of Kalanchoe daigremontiana (left), K. ×houghtonii ‘Garbí’ (centre), and K. delagoensis (right). The flower colour of K. ×houghtonii ‘Garbí’ is intermediate between that of the two parents. The flowers of K. daigremontiana are uniformly dull light pinkish purple, while those of K. delagoensis show more variation, with some forms, such as this one, being bright orange, while others can vary from dull orange to bright red. The flower of K. delagoensis (right) is 28 mm long, excluding the pedicel. Photograph: Gideon F. Smith.