Malesian Euphorbiaceae Descriptions

23. CHAETOCARPUS

 

P.C. van Welzen

 

Welzen, P.C. van. 1994. A taxonomic revision of S.E. Asian Chaetocarpus Thwaites (Euphorbiaceae). Rheedea 4: 93–101.

Welzen, P.C. van & H.-J. Esser. 2013. Peraceae. In: Nooteboom, H.N. & van Welzen, P.C. (eds.), Flora Malesiana ser. 1, 21: 119–133.

 

Phylogeny of the Erismantheae

 

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Genus description

Species description

 

Chaetocarpus Thwaites

 

    Chaetocarpus Thwaites, Hooker's J. Bot. Kew Gard. Misc. 6 (1854) 300; Baill., Et. Gen. Euph. (1858) 323; Thwaites, Enum. Pl. Zeyl. (1861) 274; Müll.Arg. in DC., Prod. 15.2 (1866) 1121; Kurz, For. Fl. Br. Burma 2 (1877) 408; Hook.f., Fl. Brit. India 5 (1887) 460; Pax in Engl. & Prantl, Nat. Pflanzenfam. 3, 5 (1890) 89; Nat. Pflanzenfam. Nacht. II-IV. Teil (1897) 212; Craib, Contr. Fl. Siam, Aberdeen Univ. Stud. 57 (1912) 194; Pax & K.Hoffm. in Engl., Pflanzenr. IV, 147, 4 (1912) 7; Ridl., Fl. Malay Pen. 3 (1924) 310; Gagnep. in M.H.Lecomte, Fl. Gen. I.-C. 5 (1926) 471; Airy Shaw, Kew Bull. 26 (1972) 231; Whitmore, Tree Fl. Malaya 2 (1973) 76; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 67; Kew Bull. 36 (1981) 275; Welzen, Rheedea 4 (1994) 94; Radcl.-Sm., Gen. Euphorbiacearum (2001) 116; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 152; Welzen & Esser in Noot. & Welzen, Fl. Males. ser. 1, 21 (2013) 123; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 103, fig. 21. 2014. — Type: Chaetocarpus pungens Thwaites [= Chaetocarpus castanocarpus (Roxb.) Thwaites]

    Regnaldia Baill., Adansonia 1 (1860) 187; Müll.Arg. in DC., Prod. (1866) 1257. — Type: Regnaldia cluytioides Baill. [= Chaetocarpus castanocarpus (Roxb.) Thwaites]

 

Tree or shrub, dioecious. Indumentum consisting of simple, hirsute to sericeous hairs, glabrescent. Stipules very asymmetric, early caducous. Leaves simple, distichous; petiole not to slightly pulvinate; blade (a)symmetric, coriaceous, punctate; base broadly attenuate; margin entire (to laxly sinuate); apex acuminate (to cuspidate); both surfaces (sub)glabrous; venation pinnate, looped and closed at the margin, indistinctly reticulate. Inflorescences dense axillary clusters of flowers (reduced thyrses), brachyblasts increasing in size with age. Bracts on brachyblasts, 4 surrounding each flower. Pedicels in staminate flowers with break-zone halfway, elongating in fruit in pistillate flowers. Flowers actinomorphic. Sepals 4 (or 5), 2 outside (outside sericeous), and 2 (or 3; see note) inside (outside with central sericeous band), spreading horizontally or reflexed, inside glabrous, third inner sepal petal-like, often with claw. Petals absent (see note). Disc annular, lobed, toothed, teeth in pistillate flowers more numerous and narrower. Stamens absent in pistillate flowers (see note 2); in Malesia staminate flowers with an androphore from which the filaments branch alternately; latter each with an anther except for one of the lower branches with often 2 or 3 anthers; latter 8–15, basifixed, opening latrors with a slit, bend upwards, at apex a pilose 3-lobed pistillode. Pistil in pistillate flower: ovary (on short gynophore), 3- (or 4-)locular, densely hirsute; ovules one per locule, descending, epitropous, anatropous, attached halfway to column; styles 3, short, hirsute; stigmas divided up to the style, above with dendritic papillae, on lower surface hirsute. Fruit a rhegma, subglobose, in Malesia outside densely echinate with glochidiate hairs, inside glabrous, dehiscing septicidally into 3 (or 4) segments, latter almost split to the base; wall thin, woody. Seeds ovoid, flattened, 1–3 per fruit, black, glossy, covered in upper third by a thin aril; endosperm absent.

    Distribution — 10 or 11 species pantropical, one species in W. Malesia.

    Note — The third (and very seldom a fourth) inner sepal is placed within the other two sepals and is alternisepalous and thinner than the sepals. Therefore, it might as well be described as a petal (see also fig. 1b). Petals are reported to be absent in Chaetocarpus and this character is considered to be the main difference with the genus Trigonopleura. Obviously, the difference between both genera is not in the complete absence or presence of petals, but in the reduced number of petals in Chaetocarpus.

 

Chaetocarpus castanocarpus (Roxb.) Thwaites 

 

    Chaetocarpus castanocarpus (Roxb.) Thwaites, Enum. Pl. Zeyl. (1861) 275; Müll.Arg. in DC., Prod. 15 (1866) 1122; Kurz, For. Fl. Br. Burma 2 (1877) 409; Hook.f., Fl. Brit. India 5 (1887) 460; Gamble, Man. Ind. Timbers (1902) 623; Craib, Contr. Fl. Siam, Aberdeen Univ. Stud. 57 (1912) 194; Pax & K.Hoffm. in Engl., Pflanzenr. IV, 147, 4 (1912) 8; Ridl., Fl. Malay Pen. 3 (1924) 310; Gagnep. in M.H.Lecomte, Fl. Gen. I.-C. 5 (1926) 471, fig. 59: 12–16; Corner, Ways. Trees Malaya 1 (1940) 244 ('castaneicarpus'); Airy Shaw, Kew Bull. 26 (1972) 231; Whitmore, Tree Fl. Malaya 2 (1973) 76; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 67; Kew Bull. 36 (1981) 275; Jarvie & Perumal, Tropics 3 (1994) 159; Welzen, Rheedea 4 (1994) 98, Fig. 1, Map1; Welzen in Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 153, fig. 33, plate VIII: 1.1, 1.2; Welzen & Esser in Noot. & Welzen, Fl. Males. ser. 1, 21 (2013) 124, fig. 1; plate 1; map 1. — Adelia castanicarpa Roxb., Fl. Ind. 3 (1832) 848. — Chaetocarpus castanocarpus (Roxb.) Thwaites var. genuina Müll.Arg. in DC., Prod. 15 (1866) 1122, nom. inval. — Gaedawakka castanocarpa (Roxb.) Kuntze, Rev. Gen. 2 (1891) 606, nom. superfl. (see note 1). — Type: Icones Roxbughianae (K, holo), India, Bengal, Boolkokra.

    Chaetocarpus pungens Thwaites, Hooker's J. Bot. Kew Gard. Misc. 6 (1854) 301, fig. 10A: 1–5, p.p., excl. description of fruit + fig. 10A: 6–9 (Thwaites, 1861). — Type: CP (Thwaites) 2641 (K, holo, n.v.; iso in L, UC), Ceylon.

    Regnaldia cluytioides Baill., Adansonia 1 (1860) 188, pl. VII: 7, 8; Müll.Arg. in DC., Prod. (1866) 1257. — Type: Walker s.n., 1846 (P, holo, n.v.), Ceylon.

    [Bradleia ? coriacea Wall., Cat. (1847) 7872 (BM, K, NY), Malaysia, Penang, nom. nud.]

    [Casearia ? coriacea Wall., Cat. (1847) 7196 (K, L), nom. nud.]

 

                Chaecast-habit.gif (44990 bytes)    Chaecast-male.gif (46244 bytes)    Chaecast-female.gif (41424 bytes)    Chaecast-fruit.gif (29040 bytes)

 

Tree (or shrub) up to 45 m high, girth up to 3 m, d.b.h. up to 60 cm; buttresses usually absent or indistinct, up to 1.2 m long, c. 7.5 cm thick; flowering branches 1–4 mm thick. Outer bark (smooth to) flaky, finely fissured, peeling off in 1–2 cm wide strips, coarsely granular, white to brown-grey to reddish brown to deep purple-brown, up to 2 mm thick; inner hard, gritty, salmon to red to purplish brown, up to 1 cm thick; cambium white to pale yellow. Sapwood white, to yellow-brown; heart wood pale reddish brown. Leaves: stipules falcate, 3–6.5 by 0.6–2.2 mm, subglabrous to subsericeous; petiole 3–17 mm long, reniform in transverse section, with grooves across; blade ovate (to elliptic), 3.5–18.5 by 1.5–8 cm, index 1.8–3.5, very apex narrowly rounded to mucronulate, nerves 7–9 per side. Inflorescences densely hirsute. Bracts triangular, c. 0.8 by 1 mm. Flowers greenish yellow to white-yellow to yellow, slightly fragrant, sweet, staminate flowers 2.2–3.7 mm in diam., pistillate flowers up to 7.5 mm in diam. Pedicels woolly, in staminate flowers 3.8–4.6 mm long, in pistillate flowers 3.3–5 mm long. Sepals ovate to rounded, 1.5–3 by 1.5–3.3 mm. Disc pink to red. Stamens in staminate flowers: androphore 2.8–5 mm long, hairy, white; filaments 0.4–1 mm long; anthers triangular to elliptic, 0.5–1.2 by 0.4–0.6 mm, (hairy), yellow. Pistil in pistillate flower: (gynophore up to 0.4 mm high); ovary ovoid, 1–1.3 mm high; styles 3, 0.3–1.2 mm long; stigma lobes 1–2 mm long. Fruit 8–18 by 80–18 mm, yellow turning reddish brown, glochidiate hairs c. 3 mm long. Seeds 5.2–5.5 by 3.5–5 by 2.7–3.5 mm; aril red. Embryo ovoid, flattened, c. 4.3 by 3 mm; plumule and radicle c. 0.7 mm long.

    Distribution — Sri Lanka, India, Assam, Andamans, Burma, Cambodia, Vietnam, Thailand, and W Malesia: Malay Peninsula (not recorded for Singapore), Sumatra, and Borneo (Brunei, Kalimantan, Sabah, Sarawak). The New Guinean specimens are regarded to be misidentifications or the result of label switches. 

 

Chaecast-map.gif (415722 bytes)

 

    Habitat & Ecology — Often common, but scattered in (hilly) primary and secondary lowland forest, mixed dipterocarp forest, coastal peat-swamp forest (kerangas), seasonally swampy forest, Schima-bamboo forest, along beaches and river banks, and in submontane scrubs. Soil: yellow, brown or black sandy soil, sandy loam, sandstone, yellow clay, clay-loam, rocky coral, or granite. Alt.: sea level up to 500 m. (Partly after Airy Shaw, 1972, 1975, 1981.) According to Whitmore (1973) a calcifuge, because it is common along the coast in NE Malaysia and the inland collections may reflect old Pleistocene shore lines. However, the plants are also found in a far more acid surrounding, therefore, Ch. castanocarpa is more likely to be a very tolerant species capable of growing in a wide variety of soils. Flowering and fruiting whole year through.

    Uses — In N.E. Malaysia (Kelantan and Trengganu) the young leaves are cooked and eaten as spinach or chopped up with rice (Corner, 1940). The wood is used as a non-construction timber by the Iban, Sarawak, Borneo (Jarvie & Perumal, 1994), for building purposes in Ceylon (Gamble, 1902), and for sampans and columns in Indochina (Gagnepain, 1926). The wood is said to be light red, moderately hard, close-grained, pores small, scanty, in short radial lines, medullary rays very fine, very numerous, narrow wavy concentric bands fairly regular and prominent (Gamble, 1902).

    Malesian vernacular names — Malaysia: Batu, membatu (Corner, 1940). Sumatra: Besie, kaju besi(e) (Malay). Borneo: Dengin-bobok (Bassap-Mapulu); dusun bukit (Tidong); kaju dusun, nampadu (Malay); masam (Serawak-Dyak); mauhi (Bajar Malay); medang serukan (Brunei Dusun); pingas (Sungei); r'teh r'teh (Medong Serokan); boekir, djamilas, djentian, oebar bantan, perupuk batu (Kalimantan area); obah nasih (Sandakan Prov.).

    Notes — 1. O. Kuntze (1891) made a new combination in the genus Gaedawakka L. (Fl. Zeyl., 1747, 203). This combination is superfluous, because the description of Gaedawakka predates the starting date of 1 May 1753 (art. 13.1a, I.C.B.N. 1988).

2. One specimen with pistillate flowers (Forest Guard 3, Malaysia, BM) showed 3 filaments attached to the gynophore, all other pistillate flowers were devoid of stamens.

3. The species is fairly constant, the infraspecific variation is quite narrow. Leaves on Malaysia are usually much larger than those on Sumatra, with the Bornean specimens in between. The pilosity varies, plants in Malaysia are (early) glabrous, while on Sumatra and especially in NE Borneo the leaves can be subpilose and the branches pilose, although glabrescent. On Borneo the leaves tend to be more elliptic than ovate (Malaysia, Sumatra). The staminate flowers in Malaysia are usually much larger than those on Sumatra, also with the Bornean specimens in between.