Seyrigia Keraudren (Bull. Soc. Bot. France 107: 298, 1961). Type: Seyrigia gracilis Keraudren. – Coniandreae – Lit: Keraudren (1966: Flora Madagascar). Distr: Madagascar. Etym: For André Seyrig (1897–1945), French miner, colonist and amateur entomologist, from 1928 in Madagascar.

Perennial dioecious succulent-stemmed climbers to 3 m; R with tuberous often sausage- or potato-like swellings; stems sometimes angular, richly branched, erect or scandent with the support of the surrounding scrub, fleshy, grey to white-felted, soon leafless; tendrils simple; L 3-lobed, ± 0.3 cm, rudimentary and early deciduous; Fl small, whitish-yellow to greenish; male Fl in pedunculate ± congested racemes; hypanthium cup- to funnel-shaped; Sep 2 mm, triangular; Pet 1–3 mm, elliptic-lanceolate; St 2; Fil short, distinct; Anth 2-thecous, thecae straight; female Fl solitary or in pairs, similar to male flowers, with 2 staminodes; Ov ovate-oblong, with 2 placentae; Sty 2; Sti lobed; Fr globose or obconical to ovoid, fleshy, ± 2 cm, apiculate or rostrate, glabrous, indehiscent, bright red at maturity; Se 2–4 per fruit, 6–7 × 4 mm, enveloped in a transparent arilloid and red pulp, brown, slightly sculptured, margin indistinct. – Cytology: n = 13 (Keraudren 1968).

All 6 species of the genus are succulent and treated below. The combination of tuberous roots and leafless thin succulent stems is quite unique. Godfrey & al. (2016) mention herbivory by two species of lemurs.

S. bosseri Keraudren (Bull. Soc. Bot. France 109: 101–102, 1962). Type: Madagascar, Toliara (Keraudren 1515 [P]). – Distr: S Madagascar (Toliara); dry bushland on gneissic rocks. I: Keraudren (1966: 13); Rauh (1998: 191).

Climbers; stems thick, 5-angled, longitudinally grooved, with dense grey woolly hairs, branching, leafless when mature; Fl small, yellowish; male Fl 12–18 in racemes to 2 cm; hypanthium campanulate, 1.5 mm; Pet 1 × 0.6 mm, finely pubescent; female Fl solitary or paired, similar to male flowers; Fr 1 cm, shortly apiculate, glabrous, red.

S. gracilis Keraudren (Bull. Soc. Bot. France 107: 299, 1961). Type: Madagascar, Toliara (Perrier 12832 [P]). – Distr: S Madagascar (Toliara); dry forests and bushland, 0–200 (−500) m. I: Keraudren (1966: 9); Rauh (1998: 191); Eggli (2008: 285). – Fig. 1.

Fig. 1
figure 1

Seyrigia gracilis (without known wild origin; cult. Sukkulenten-Sammlung Zürich). (Copyright: U. Eggli)

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Weak scramblers; stems slender, branching, fleshy, subcylindrical; Br minutely hairy to ± glabrous; male Fl 6–8 in short dense racemes; Ped 1–3 mm; hypanthium cup-shaped, 3–4 mm; Pet 3 × 1.5 mm, yellowish, finely pubescent; female Fl solitary or paired, subsessile; Cl as in male flowers; Fr obconical, beaked, 2 cm.

S. humbertii Keraudren (Bull. Soc. Bot. France 107: 299, 1961). Type: Madagascar, Toliara (Humbert 19947 [P]). – Distr: S Madagascar (Toliara); dry forest on limestone ridges and sand, 0–300 m. I: Keraudren (1966: 13); Rowley (1987: 51); Rauh (1998: 192–194); Gratias (2019). – Fig. 2.

Fig. 2
figure 2

Seyrigia humbertii. (Copyright: J. Trager)

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Weak scramblers; stems cylindrical, fleshy, furrowed, densely white-felted; male Fl 6–8 in short dense racemes; Ped 7–8 mm; hypanthium campanulate, very short; female Fl solitary or paired, similar to male flowers; Fr ovoid, apiculate, bright red.

S. marnieri Keraudren (Bull. Soc. Bot. France 114 (9): 446–447, ills., 1967). Type: Madagascar, Toliara? (Montagnac s.n. in Marnier 5 [P]). – Distr: S Madagascar (Toliara); limestone in dry bush. I: Rauh (1998: 195).

Weak scramblers; stems thin, branching, fleshy, subcylindrical, greyish-green mottled with white, minutely hairy to ± glabrous; male Fl 6–8 in short dense racemes; Ped 1–3 mm; hypanthium cup-shaped, 3–4 mm; Pet 3 × 1.5 mm, yellowish, finely pubescent; female Fl solitary or paired, similar to male flowers; Fr obconical, beaked, 2 cm.

S. multiflora Keraudren (Bull. Soc. Bot. France 107: 299, 1961). Type: Madagascar, Toliara (Keraudren 1083 [P]). – Distr: S Madagascar (Toliara); dry forest on limestone and red sand, 0–350 (−900) m.

Weak scramblers; stems climbing, fleshy, angular, minutely grey-felted; male Fl numerous, in racemes to 2 cm; hypanthium campanulate, 1–1.5 mm; female Fl solitary or paired, similar to male flowers; Fr ovoid or subellipsoid, apiculate, glabrous, red.

S. napifera Rauh (Succ. Xerophyt. Pl. Madagascar 2: 193, ills. (pp. 195–196), 1998). Type: Madagascar, Toliara (Rauh 68582 [HEID]). – Distr: S Madagascar (Toliara); sandy soil in Alluaudia bush.

Climbers with thick napiform tapR to 20 × 7–8 cm ⌀; stems thin, 4-angled, 3–5 mm ⌀, usually wine-red, with dense curled white hairs, few-branched; tendrils sometimes absent; L trifoliolate, very small, petiolate, leaflets lanceolate, canaliculate, succulent, red-brown, laxly hairy; male Fl not known; female Fl solitary in the axils of small bracts, spreading horizontally, 2–3 mm pedicellate; hypanthium short, glabrous; Pet pale brown, lobes triangular-obtuse, spreading, 2 mm, margin with short white hairs; Fr said to be unknown in the protologue but illustrated l.c. p. 196, ovoid, ±2 cm, shortly beaked, orange-red, glabrous.