Croton argyratus
Croton argyratus Blume, Bijdr: 602. 1826; Miq., Fl. Ind. Bat. 1, 2: 380. 1859; Müll.Arg. in DC., Prodr. 15, 2: 526. 1866; Ridl., Fl. Malay Pen. 3: 260. 1924, p.p. excl. C. adumbratus; Backer & Bakh.f., Fl. Java 1: 476. 1963; Airy Shaw, Kew Bull. 26: 243. 1972, p.p. as to Peninsular colls.; Whitmore, Tree Fl. Malaya 2: 85. 1973, p.p. excl. C. adumbratus; Corner, Wayside Trees Mal., ed. 3: 283. 1988, p.p. excl. C. adumbratus; Chakrab. & N.P.Balakr., Bull. Bot. Surv. India 34: 22. 1997 (‘1992’), p.p.; Esser in Chayamarit & Welzen, Fl. Thailand 8, 1: 193,, fig. 45, plate X: 2. 2005.
Bushy tree to tree to 10 m tall, dbh to 20 cm, girth to 40 cm; bark grey brown, smooth, inner bark pink; young branchlets pubescent, glabrescent. Indumentum consisting of stellate to stellate-lepidote, hyaline hairs with a small brownish center (appearing silvery) on leaves and sepals, creamish-brown hairs on leaf veins and fruits, flat, sometimes with a central porrect radius, 0.2-0.3 mm in diam., with c. 15-17 free to partly fused radii. Stipules (2.5-)4-5 mm long, pubescent. Leaves alternate to apically crowded; petiole 5-12 cm long, densely pubescent; blade elliptic, 14-20 by 6-11 cm, index 1.5-2.3, chartaceous, base acute to obtuse but the very base distinctly cordate and slightly peltate, margin entire, apex short-acuminate, nearly glabrous above (few hairs in the very base), below completely and densely silvery-pubescent without visible surface and not glabrescent, brownish hairs only on the largest veins and on immature leaves; basal glands flat, sessile, 1-1.5 mm in diam., lateral on the abaxial midrib base, marginal glands absent; side veins 8-10 pairs, not triplinerved, veinlets visible. Inflorescences yellowish-green to silvery, never crowded, 12-25 cm long, with 7-12 pistillate flowers, without bisexual bracts; densely and persistently pubescent throughout; bracts 1-2 mm long, stiff, eglandular, caducous. Staminate flowers densely pubescent; pedicel 5-6 mm long; sepals 3 by 1.5 mm; petals 3.5 by 1 mm, whitish lanate; stamens c. 10-12, glabrous or with partly pubescent filaments. Pistillate flowers densely pubescent; pedicel 4-6 mm long (10-13 mm in fruit); sepals 4-5 by 1.5-2.5 mm, fused at the base, spreading at the apex, much longer than the ovary; petals absent or as tiny scales up to 1 by 0.3 mm long; ovary 2 mm long; stigmas 3-4 mm long, free at base, undivided for up to 1 mm at the base, once bifid apically. Fruits 12-16 by 12-16 mm, not sulcate, densely pubescent. Seeds flattened, 10-11 by 7-8 mm, ecarunculate.
T h a i l a n d.— PENINSULAR: Krabi (Ko Lanta), Nakhon Si Thammarat (Khao Luang, Garome Waterfalls), Songkhla (Boriphat Waterfalls, Ton Nga Chang), Narathiwat (Bacho, Waeng).
D i s t r i b u t i o n.— Thailand, W. Malesia: Malay Peninsula, Sumatra, Java (type), Lesser Sunda Islands, Borneo, Philippines.
E c o l o g y.— Open areas, hill slopes and partly disturbed places in evergreen forest, secondary forest in rubber plantation, at rocky streams and roadsides. Altitude: 50-400 m. Flowering: April-June, September, December; fruiting: August-November, January. Inflorescences very fragrant and with much nectar.
V e r n a c u l a r.— Plao ngoen (เปล้าเงิน) (Pattani); mai lot (ไม้ลอด), plao (เปล้า) (Peninsular).
N o t e s.— C. argyratus is characterized by purely silvery-pubescent leaves without any brownish hairs when mature, usually cordate at the base, and a very constant fruit size of 12-16 mm. The name has often been misapplied to numerous Asian species with silvery-pubescent leaves. The true species does not occur in Thailand north of the Peninsula.
Croton argyratus Blume, Bijdr: 602. 1826; Miq., Fl. Ind. Bat. 1, 2: 380. 1859; Müll.Arg. in DC., Prodr. 15, 2: 526. 1866; Ridl., Fl. Malay Pen. 3: 260. 1924, p.p. excl. C. adumbratus; Backer & Bakh.f., Fl. Java 1: 476. 1963; Airy Shaw, Kew Bull. 26: 243. 1972, p.p. as to Peninsular colls.; Whitmore, Tree Fl. Malaya 2: 85. 1973, p.p. excl. C. adumbratus; Corner, Wayside Trees Mal., ed. 3: 283. 1988, p.p. excl. C. adumbratus; Chakrab. & N.P.Balakr., Bull. Bot. Surv. India 34: 22. 1997 (‘1992’), p.p.; Esser in Chayamarit & Welzen, Fl. Thailand 8, 1: 193,, fig. 45, plate X: 2. 2005.
Bushy tree to tree to 10 m tall, dbh to 20 cm, girth to 40 cm; bark grey brown, smooth, inner bark pink; young branchlets pubescent, glabrescent. Indumentum consisting of stellate to stellate-lepidote, hyaline hairs with a small brownish center (appearing silvery) on leaves and sepals, creamish-brown hairs on leaf veins and fruits, flat, sometimes with a central porrect radius, 0.2-0.3 mm in diam., with c. 15-17 free to partly fused radii. Stipules (2.5-)4-5 mm long, pubescent. Leaves alternate to apically crowded; petiole 5-12 cm long, densely pubescent; blade elliptic, 14-20 by 6-11 cm, index 1.5-2.3, chartaceous, base acute to obtuse but the very base distinctly cordate and slightly peltate, margin entire, apex short-acuminate, nearly glabrous above (few hairs in the very base), below completely and densely silvery-pubescent without visible surface and not glabrescent, brownish hairs only on the largest veins and on immature leaves; basal glands flat, sessile, 1-1.5 mm in diam., lateral on the abaxial midrib base, marginal glands absent; side veins 8-10 pairs, not triplinerved, veinlets visible. Inflorescences yellowish-green to silvery, never crowded, 12-25 cm long, with 7-12 pistillate flowers, without bisexual bracts; densely and persistently pubescent throughout; bracts 1-2 mm long, stiff, eglandular, caducous. Staminate flowers densely pubescent; pedicel 5-6 mm long; sepals 3 by 1.5 mm; petals 3.5 by 1 mm, whitish lanate; stamens c. 10-12, glabrous or with partly pubescent filaments. Pistillate flowers densely pubescent; pedicel 4-6 mm long (10-13 mm in fruit); sepals 4-5 by 1.5-2.5 mm, fused at the base, spreading at the apex, much longer than the ovary; petals absent or as tiny scales up to 1 by 0.3 mm long; ovary 2 mm long; stigmas 3-4 mm long, free at base, undivided for up to 1 mm at the base, once bifid apically. Fruits 12-16 by 12-16 mm, not sulcate, densely pubescent. Seeds flattened, 10-11 by 7-8 mm, ecarunculate.
T h a i l a n d.— PENINSULAR: Krabi (Ko Lanta), Nakhon Si Thammarat (Khao Luang, Garome Waterfalls), Songkhla (Boriphat Waterfalls, Ton Nga Chang), Narathiwat (Bacho, Waeng).
D i s t r i b u t i o n.— Thailand, W. Malesia: Malay Peninsula, Sumatra, Java (type), Lesser Sunda Islands, Borneo, Philippines.
E c o l o g y.— Open areas, hill slopes and partly disturbed places in evergreen forest, secondary forest in rubber plantation, at rocky streams and roadsides. Altitude: 50-400 m. Flowering: April-June, September, December; fruiting: August-November, January. Inflorescences very fragrant and with much nectar.
V e r n a c u l a r.— Plao ngoen (เปล้าเงิน) (Pattani); mai lot (ไม้ลอด), plao (เปล้า) (Peninsular).
N o t e s.— C. argyratus is characterized by purely silvery-pubescent leaves without any brownish hairs when mature, usually cordate at the base, and a very constant fruit size of 12-16 mm. The name has often been misapplied to numerous Asian species with silvery-pubescent leaves. The true species does not occur in Thailand north of the Peninsula.