Croton griffithii Hook.f.

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 : 14-15

8. Croton griffithii Hook.f.

Croton griffithii Hook.f. (1887) 392; Ridl. (1924) 261; Burkill (1935) 689; Airy Shaw (1972a ‘ 1971 ’) 246; Esser (2002b) 42; (2005) 205. — Oxydectes griffithii (Hook.f.) Kuntze (1891) 614. — Lectotype (designated by Esser 2002b: 42): Griffth KD 4781 (lecto K, 2 sheets [K000959159]!, K000959160]!), Malaysia, Malacca.Both K sheets are the same collection (labeled sheet 1 and 2) and together can be regarded as the lectotype.Other syntypes: Griffith KD 4778 (K [K000959159!], K000959160!]), Malaysia, ‘Malacca’; King’s Collector 1115 (G!, K!, L!), Malaysia, Perak; King’s Collector 4484 (CAL [CAL0000023613]*,K!), Malaysia, Perak; King’s Collector 4629 (CAL [CAL0000023608]*), Malaysia, Perak; King’s Collector 4820 (CAL [CAL0000023605*]), Malaysia, Perak, Goping; King’s Collector 6157 (K!, WU!), Malaysia, Perak; Maingay 1406 (CAL [CAL0000023612*], K!), Malacca; Scortechini s.n. (CAL [CAL0000023611*], K!, SING!), Malaysia, Perak; Scortechini 1423 (CAL [CAL0000023610*], Malaysia, Perak; Wallich numer. list 7754 (K-W!), Singapore; Wallich numer. list 7967 (K-W, n.v.), Singapore.

Croton confusus Gage (1922) 237 (‘ confusum ’). — Syntypes: Curtis 1585 (A [00106965]!, K!, SING!), Malaysia, Penang, Moniots Road; Hullet s.n. (SING, n.v.), Singapore, Sungei Bei; King’s collector 5452 (n.v.), Malaysia, Perak, Larut; Ridley 3170 (CAL [ CAL0000023570 *], SING, n.v.), Malacca, Mount Ophir and Gunong Ledaung; Ridley 3446 (SING, n.v.), Singapore, Changi ; Ridley 7642 (SING, n.v.), Malaysia, Selangor, Guning Bua ; Ridley 10404 (SING, n.v.), Singapore, Bukit Timah ; Ridley 10860 (SING, n.v.), Singapore, Bukit Timah ; Ridley 12561 (SING, n.v.), Singapore, Woodlands ; Ridley s.n. (n.v.) Singapore,Botanic Garden. (When the species is revised in its full distribution, then a lectotype should be designated).

Croton laevifolius auct. non Blume: Whitmore (1973) 85, p.p. excl. C. laevifolius ; Corner (1988) 284, p.p. excl. C. laevifolius .

Shrubs or trees,to 18 m tall (up to 26 m in Borneo),diam to 90 cm; young branchlets densely pubescent, glabrescent (later than most other Croton species). Outer bark smooth but brittle and patchy, light greyish brown. Indumentum consisting of only whitish hyaline stellate trichomes with a yellowish centre, 0.1–0.4 mm diam (up to 0.6 mm on developing ovaries), flat but often with a very short central porrect radius, with 11–17 free radii. Stipules subulate to ensiform, (1.5–)2.5–5 by 0.4–1 mm, densely pubescent on both sides, caducous to quite persistent. Leaves alternate to apically crowded or almost whorled, 2 –6 per pseudo-whorl; petiole (0.5–) 2–11 cm long, grooved above, very thick (up to 4 mm diam), with scattered trichomes to slightly pubescent; glands abaxially as flat discs lateral on the very base of the midrib, (0.3–) 0.7–1.5 mm diam, sessile, not to distinctly elevated; blade elliptic, (8.5–)10–26 by (3–) 5–12 cm, (1.7–)2–3(–3.8) times longer than wide, chartaceous, base rounded to obtuse (rarely subcordate or attenuate), margin subentire (to shallowly serrate especially in young leaves, teeth without trichomes or glands apically), apex acute to acuminate, adaxial side glabrous, abaxial side of old leaves densely whitish pubescent (with epidermis visible) to subglabrous, epidermis visible, in young leaves completely whitish pubescent with surface hardly visible, sometimes more densely pubescent at the very base of the midrib; venation distinct, sunken above, basally not triplinerved, secondary veins (6–)11–15. Inflorescences both terminal and axillary, 8– 30 cm long, with scattered trichomes, basally 6–15 pistillate flowers, often 1–3 staminate flowers on the same node of a pistillate flower,apically 1–3 staminate flowers per node; bracts triangular-ovate, c. 1 by 0.5 mm, both sides subglabrous, with a patch of simple trichomes at the apex, eglandular, quite persistent. Staminate flowers c. 4 mm diam; pedicel 1.5–4(–6) mm long, round to flattened, subglabrous (to slightly pubescent); sepals triangular-ovate, 1.5–2 by 1–1.5 mm, fused at base, dark around base, hyalinewhitish near apex, outside with scattered trichomes to subglabrous; petals oblong, 1.5–2 by 0.3–0.5 mm, outside glabrous; stamens 8 –12, filaments 2–3 mm long, anthers c. 0.6 by 0.4 mm. Pistillate flowers 3–4 mm diam; pedicel 1–3 mm long, not sulcate, slightly to densely pubescent; sepals triangular, 1.5–2 by 1–1.5 mm, outside densely to slightly pubescent, denser near base, with a patch of simple trichomes at the apex, as long as ovary; petals absent; ovary globose to obovoid, 1.5–2 by 1.5–2 mm, deeply sulcate, densely pubescent; style absent; stigmas 3–4.5 mm long, once divided to 1.5–3 mm from apex. Capsules 3-lobed, obovoid, 5–8 mm high, diam 7–14 mm, extremely sulcate when dry, with scattered trichomes; pericarp strong and thick (c. 0.8 mm); columella c. 8 mm long. Seeds ovoid but flattened on inner side, 7–9 by 5–6 mm, glabrous, with a small caruncle.

Distribution — Thailand, Malesia: Malay Peninsula (Perak, Selangor, Pahang, Terengganu, Johor), Sumatra (Sumatera Barat (Siberut), Kepulauan Riau (Singkep)), Borneo.

Habitat & Ecology — In evergreen forest and along streams, on granite bedrock.Altitude: 40– 850 m. Flowering: February– April; fruiting: July, August.

Affinities — Riau pocket group ( Van Ee et al. 2015; clade I 4 in Fig. 1 ).

Uses — A decoction of the leaves is used in Malaysia as bath after childbirth ( Esser 2005).

Notes — 1. The leaves usually dry into a typical yellowish brown colour. The species is not known from the main island of Sumatra; one specimen is known from Pulau Singkep (one of the Riau islands) and the other from Pulau Siberut (Mentawai islands, west of Sumatra). Other specimens examined are from Sarawak and Malay Peninsula.

2. Three specimens were wrongly determined as C. erythrostachys . The main differences between these two species are that C. erythrostachys has marginal leaf glands on a long stalk and large trichomes (0.6–07 mm diam) with 9–10 radii spreading in all directions. The flowers and capsules of C. griffithii are smaller and less hairy.

Figures

Fig. 1 Bayesian phylogram based on ITS sequences excluding the 5.8S region. The values at nodes represent the Bayesian-inference posterior-probability support values. Astraea and Brasiliocroton are outgroups. Black names: New World, yellowish brown: Africa–Madagascar, green: mainland Asia, blue: Aus- tralia–West Pacific,red: Malesia.Accessions with bold names correspond to the newly sequenced taxa, all ocurring in Sumatra. Bar: nucleotide substitutions.