Croton argyratus Blume

Beyer, J., Esser, H. - J., Eurlings, M. C. M. & Welzen, P. C. van, 2023, A revision of the genus Croton (Euphorbiaceae) in Sumatra (Indonesia), Blumea 68 (1), pp. 1-25 : 8-10

2. Croton argyratus Blume — Fig. 3d–f

Croton argyratus Blume (1826) 602 (‘ argyratum ’); Müll.Arg. (1866) 526; Hook.f. (1887) 385; J.J.Sm. (1910) 336; Merr. (1921a) 336; (1923) 425; Ridl.(1924) 260, p.p. (‘ argyratum ’); Gagnep.(1925) 277;Merr.(1926) 381; (1929) 156; Burkill (1935) 688; M.R.Hend. (1939) 70; Backer & Bakh.f. (1963) 476; Airy Shaw (1972a ‘ 1971 ’) 243; Whitmore (1973) 85; Airy Shaw (1975) 90; (1976) 385; (1980a) 616; (1981a) 284; (1982a) 14; (1983) 17; Corner (1988) 283, text-f.81; Chakrab. & N.P.Balakr. (1997 ‘1992’) 22,f. 1, map 1; Esser (2005) 193, f. 45,plate X: 2; Esser & Veldkamp (2008) 169, f. 1d–f; Chakrab.(2019) 629. — Croton argyratus Blume var. genuinus Müll. Arg. (1866) 526,nom. inval. — Oxydectes argyrata (Blume) Kuntze (1891) 611. — Lectotype (designated by Esser & Veldkamp 2008): Blume s.n. (lecto L [L0233566]!;possible isolecto A [00106971]!,BM [BM000630468]! as no. 230, P n.v.), Indonesia, Java. Airy Shaw (1980a) appointed Blume s.n. (BO) ‘in sylvis montium calcareorum Provinciarum occidentalium Javae’ as type, but that text is copied from Blume (1826), and does not appear as such on labels, therefore no specific specimen was mentioned and thus no lectotypification).

Croton bicolor Roxb. [(1814) 69,nom.nud.], (1832) 680. — Oxydectes bicolor (Roxb.) Kuntze (1891) 611. — Lectotype (designated by Chakrabarty & Balakrishnan 1997: 22): Icones Roxburgianae 2558 (lecto CAL (2561 on drawing); isolecto K (2551 on drawing)), Indonesia, Sumatra, probably Bengkulu, Fort Marlborough.

Croton zollingeri Miq. (1859) 381. — Lectotype (designated here): Zollinger 963­Z (lecto U [ U 007936 ]!, as Unknown s.n.; isolecto A [0010017]!), Indonesia, Java.

Croton argyratus Blume var. hypoleucus Müll.Arg. (1864) 483; (1866) 526. — Lectotype (designated by Esser & Veldkamp 2008): Motley 758 (lecto K [ K000959191 ]!), Borneo, Banjarmasin.

Croton argyratus Blume var. brevipes Müll.Arg. (1866) 527. — Lectotype (designated by Esser & Veldkamp 2008): Zollinger 3212 (lecto G-DC [ G00311485 ]!; isolecto A [00047510]!, G [ G00434384 ]!, [ G00434386 ]!), Indonesia, Java.

Croton argyratus Blume var. gracilis Müll.Arg. (1866) 527. — Lectotype (designated by Esser & Veldkamp 2008): Zollinger 3809 (lecto G-DC [ G00311486 ]*; isolecto BM [ BM000630468 ]!, CAL [ CAL0000023639 ]*, G [ G00434385 ]!, W [1889-0074726]!), Indonesia, Bali.

Croton avellaneus Croizat (1942b) 498. — Type: BS (Ramos & Edaño) 43977 (holo A [00047539]!; iso BM!, G!, W [1930-0001714]!), Philippines, Sulu Archipelago, Tawitawi .

Trees, to 30 m tall, dbh to 40 cm; young branchlets densely pubescent, slightly glabrescent. Outer bark smooth, dark grey; inner bark white to pink. Indumentum consisting of stellate to stellate-lepidote, hyaline trichomes with a small brownish centre on leaves and sepals, creamish brown trichomes on leaf veins and capsules, 0.2–0.4 mm diam, flat, often with a central porrect radius, with 15–25 free to slightly fused radii. Stipules filiform to subulate, (3–)8–20(–25) by 0.3–2 mm, densely pubescent on both sides, caducous. Leaves alternate; petiole (2–)4–12(–15) cm long, sulcate, slightly grooved above, densely pubescent; glands as flat discs lateral on the very base of the midrib, 1–1.5 mm diam, sessile, often hard to spot; blade elliptic to slightly ovate, 9–22 by 5.5–10 cm, 1.5–2.3(–2.9) times longer than wide, chartaceous, base obtuse to rounded with very base distinctly cordate and slightly peltate, margin entire to subserrate, apex acuminate, adaxial side glabrous, abaxial side completely and densely silvery-pubescent without visible surface and not glabrescent, brownish trichomes only on the largest veins and on immature leaves; venation distinct, sunken above, raised below, very indistinct to distinct with 3 or 5 prominent basal veins, secondary veins 8–10 pairs, higher order nerves distinct. Inflorescences 1(–3) per node, 10–22(–30) cm long, bisexual (occasionally one sex only), densely pubescent all over, basally 7–17(–26) pistillate flowers, rarely 1–2 staminate flowers in the same cymule of a pistillate flower, apically 1–3 staminate flowers per node; bracts ensiform to triangular-ovate, 1.3–2 by 0.5–0.8 mm, densely pubescent outside, inside subglabrous, caducous. Staminate flowers 5–6.5 mm diam; pedicel 4–6 mm long, round, densely pubescent; sepals triangular-ovate, c. 2.5 by 0.5 mm, outside densely pubescent; petals oblong, c. 2.8 by 1 mm, outside glabrous to slightly lanate; stamens 11–15, filaments 3–4 mm long, anthers 1–1.5 by 0.2–0.5 mm. Pistillate flowers 8–9 mm diam; pedicel 4–6 mm long (up to 12 mm in fruit), sulcate, densely pubescent; sepals elliptic, 4–6 by 2–3 mm, apex obtuse (to acute), outside densely pubescent, inside slightly lanate, much longer than ovary; petals elliptic, c. 3 by 1.5 mm, apex acute, outside densely pubescent, inside with scattered trichomes, margin lanate, usually absent; ovary globose, 2– 3 by 2 – 3 mm, densely yellowish brown pubescent; style less than 0.4 mm long, densely pubescent; stigmas 6–8 mm long, once divided to 5–7.5 mm from apex, pubescent near base. Capsules globose (sometimes near obovoid), (10–) 13–19 mm high by (10–) 12–18 mm diam, not sulcate, densely pubescent; pericarp very thick (1–2 mm) and woody; columella 12–15 mm long. Seeds ellipsoid, flattened, 11–14 by 8–11 mm, glabrous, with a very small caruncle.

Distribution — Thailand, Malesia: Peninsular Malaysia, Sumatra (Aceh, Sumatera Utara, Sumatera Barat, Riau, Jambi, Sumatera Selatan, Lampung), Java, Borneo, Philippines, Sulawesi, Lesser Sunda Islands, Moluccas.

Habitat & Ecology — Open areas, hill slopes and partly dis- turbed places in evergreen primary forest, secondary forest or mountain forest, at rocky streams and roadsides. Altitude: sea level to 1200 m. Flowering:April –June, September, December; fruiting: August–November, January.

Affinities — Croton section Argyrati ( Van Ee et al. 2015) .

Vernacular names — Kayu bulan ( Burkill 1935), Kayu Pos- kas (Sumatera Utara), Kayu si marattimang (Sumatera Utara), Dada kedih (Aceh), Giyak putih (Lampung), Setima ( Burkill 1935).

Uses — Wood seemingly of little value, but in some areas of the Malay Peninsula used for building, or to keep fires going (Andaman Islands) as it smoulders for a long time. Decoctions of leaves and stem are used to cure diarrhoea, also given after childbirth ( Burkill 1935).

Figures

Fig. 3 a–c. Croton adumbratus Croizat. a. Habit; b. detail of cuneate leaf base, abaxial view; c. fruit. — d–f. Croton argyratus Blume: d. Habit; e. detail of narrowly emarginate leaf base, abaxial view; f. fruit (a–c: de Wilde & de Wilde­Duyfjes 19604; d–f: Chellia KEP 104397; all L). — Illustration by Anita Walsmit Sachs, 2007.