Styloid crystals in Claoxylon (Euphorbiaceae) - Red de Bibliotecas

Botanical Journal of the Linnean Society, 2008, 156, 445–457. With 12 figures 

Styloid crystals in Claoxylon (Euphorbiaceae) and 

allies (Claoxylinae) with notes on leaf anatomy 

PATRICK KABOUW 1 , PETER C. VAN WELZEN 2 *, PIETER BAAS 2 and 

BERTIE J. VAN HEUVEN 2 

1NIOO-KNAW, Department of Multitrophic Interactions, PO Box 40, 6666 GA Heteren, the 

Netherlands 

2Nationaal Herbarium Nederland, Leiden University Branch, PO Box 9514, 2300 RA Leiden, 

the Netherlands 

Received 6 March 2006; accepted for publication 27 September 2007 

Claoxylon and Micrococca are the only Euphorbiaceae genera that have rough dried leaves (fresh ones are smooth) 

because of protruding styloid (needle-like) crystals more or less perpendicular to the leaf surface, which perforate 

the epidermis and cuticle. A broad leaf anatomical study of the subtribes Claoxylinae, the monogeneric Lobaniliinae, 

and Mercurialis of the Mercurialinae (95 of a possible 235 species in all six genera) showed that styloids are 

present in Claoxylon, Discoclaoxylon, Erythrococca, Lobanilia, and Micrococca, and lacking in Claoxylopsis and 

Mercurialis. Contrary to Claoxylon, the dried leaves of Discoclaoxylon, Erythrococca, Lobanilia, and Micrococca are 

not rough, because the styloids do not perforate the epidermis during drying and therefore herbarium leaves 

generally remain smooth. The presence of styloids supports a clade in a recent molecular phylogenetic study that 

unites subtribes Claoxylinae and Lobaniliinae as Claoxylinae s.l. Mercurialis (no styloids) is sister to all other taxa 

(with styloids) in the monophyletic Claoxylinae s.l. The styloids form a synapomorphy for a monophyletic part of 

the Claoxylinae (Claoxylon, Discoclaoxylon, Erythrococca, Lobanilia, and Micrococca). Other leaf anatomical notes 

are provided, together with an overview of the occurrence of styloids, stomata, and druse crystals for most species 

in the Claoxylinae. The indumentum ranges from (virtually) absent to a sparse or dense tomentum of straight and 

thick- or thin-walled unicellular hairs (most common), curly hairs, or two-armed hairs (‘Malpighiaceous hairs’). The 

last two hair types probably form diagnostic characters for species groups within the genus Claoxylon. © 2008 The 

Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 445–457. 

ADDITIONAL KEYWORDS: Claoxylopsis – Discoclaoxylon – Erythrococca – Lobanilia – Mercurialis – 

Micrococca. 

INTRODUCTION 

The family Euphorbiaceae is one of the largest and 

most frequently encountered in South-east Asia. 

Identification – even up to genus level – is troublesome, 

but the genus Claoxylon is usually easily recognizable 

because the dried leaves of most species are 

rough (few are smooth). The surface roughness was 

used as an identification tool by Airy Shaw (1972), 

Radcliffe-Smith (2001), and van Welzen (2005). Unfortunately, 

the roughness of the leaves could not be 

observed in densely hairy species. The cause of the 

*Corresponding author. E-mail: welzen@nhn.leidenuniv.nl 

roughness was not obvious: a dissecting microscope 

showed only papillae-like extensions from the leaf. 

This leaf anatomical study was undertaken to elucidate 

the nature of the roughness. 

Claoxylon is a palaeotropical genus of c. 110 species 

(Govaerts, Frodin & Radcliffe-Smith, 2000), which 

was described by de Jussieu (1824). It ranges from 

Madagascar throughout South and South-east Asia to 

Melanesia and Hawaii. According to a molecular 

phylogenetic study by Wurdack, Hoffmann & Chase 

(2005), Claoxylon is sister to Erythrococca (50 species, 

Africa), and together they form the top of a Hennigian 

comb-like phylogeny, which further includes (from 

top to bottom) Micrococca (12 species, Palaeotropics), 

© 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 445–457 445

446 P. KABOUW ET AL. 

Lobanilia (eight species, Madagascar), Discoclaoxylon 

(four species, West Africa), and Mercurialis (eight 

species, Europe–Asia) (numbers of species and distributions 

given in Radcliffe-Smith, 2001). The clade has 

a bootstrap value of 91% (rbcL data) or 100% (trnL-F 

and rbcL and trnL-F combined). This clade more or 

less coincides with subtribe Claoxylinae (subfamily 

Acalyphoideae, tribe Acalypheae), as presented in the 

last two classifications of the Euphorbiaceae by 

Webster (1994) and Radcliffe-Smith (2001); these two 

classifications are based on morphology and were 

built on former systems (for example, Pax & Hoffmann, 

1931). Webster (1994) also included Amyrea 

(11 species, Madagascar), Claoxylopsis (three species, 

Madagascar), and Mareya (three species, Africa) in 

Claoxylinae, but excluded Lobanilia and Mercurialis. 

Radcliffe-Smith (2001) followed Webster in his classification, 

but, for Claoxylinae, he deviated by excluding 

Amyrea and Mareya. Lobanilia was placed by 

both authors in the monogeneric subtribe Lobaniliinae, 

which they considered to be closely related to 

Claoxylinae (deviating only in the presence of stellately 

bundled hairs). Mercurialis is part of subtribe 

Mercurialinae, which is considered not to be closely 

related to Claoxylinae. Other studies presenting 

classifications or discussing relationships of Claoxylon 

and its allies include Pax & Hoffmann (1931) 

(morphology), Perry (1943) (chromosome counts), 

Punt (1962) (palynology), Webster (1975) (precursor of 

the 1994 publication), and Nowicke & Takahashi 

(2002) (palynology). The phylogenetic relationships 

within Claoxylinae still comprise uncertainties. 

Webster (1994) indicated that the position of Claoxylopsis 

and Amyrea requires further evaluation. 

Nowicke & Takahashi (2002) presented evidence 

against close relationships between Claoxylopsis and 

Claoxylon, although this evidence is not very strong. 

Unfortunately, Wurdack et al. (2005) did not include 

Claoxylopsis in their study, but Amyrea and Mareya 

are unrelated to each other and the Claoxylinae, and 

both are members of different clades. Thus, only the 

precise position of Claoxylopsis is still unresolved. 

Little is known about the leaf anatomy of the genus 

Claoxylon. Most studies have mainly contained 

random observations on only a few species: Solereder 

(1908), Pax & Hoffmann (1931), Carey (1938) (comparative 

leaf anatomy of species in two habitats 

around Sydney), Metcalfe & Chalk (1950, 1979) 

(general overview), Raju & Rao (1977) (stomata development), 

and Kulshreshtha & Ahmad (1992) (cuticle 

ornamentation). A thorough leaf anatomical study of 

Claoxylon, certainly with the purpose of improving 

existing classifications, is still lacking. Solereder 

(1908) was the first to report styloid crystals in the 

leaves of Claoxylon (‘including Micrococca’). Pax & 

Hoffmann (1931: 16) very briefly reported that the 

leaf roughness in Claoxylon and its allies is caused by 

crystalliferous cells (‘. .., während die auffallende 

Rauheit der Blätter von Claoxylon und Verwandten 

auf die Größe der Kalkoxalat enthaltenden Zellen 

zurückzuführen ist’) (translated as: ‘while the striking 

roughness of the leaves of Claoxylon and allies 

can be traced to the size of the cells containing 

calcium oxalate’). Kulshreshtha & Ahmad (1992) 

provided notes on the cuticular ornamentation of 

Claoxylon indicum (Reinw. ex Blume) Hassk. and 

Micrococca oligandrum L., and Raju & Rao (1977) 

reported mucilaginous leaf epidermal cells for several 

(unspecified) Claoxylon species in their table summarizing 

data from other authors. 

The roughness of Claoxylon leaves prompted this 

study. Other genera in the Claoxylinae were also 

included, because Pax & Hoffmann (1931) indicated 

the presence of crystals for other related genera. The 

aims of this study were to clarify the cause of the 

roughness, to establish which species and genera in 

the Claoxylinae have styloids, to determine whether 

the presence of roughness and/or crystals can be 

used to delimit systematic groups, and to record 

other leaf anatomical details of potential systematic 

significance. 

MATERIAL AND METHODS 

Herbarium specimens (see Appendix) of Claoxylon, 

Claoxylopsis, Erythrococca, Lobanilia, Micrococca, 

and Mercurialis were sampled in L (Leiden, the Netherlands), 

and specimens of Discoclaoxylon mainly 

originated from WAG (Wageningen, the Netherlands). 

The following species were sampled: 74 of c. 110 

Claoxylon species (five represented by two specimens), 

one of three Claoxylopsis species, one of four 

Discoclaoxylon species (three specimens), eight of 

c. 50 Erythrococca species (two represented by two 

specimens), one of eight Lobanilia species, four of 

eight Mercurialis species, and six of 12 Micrococca 

species (one represented by two specimens). A living 

specimen of Claoxylon longifolium (Blume) Endl. was 

checked for roughness by Richard Chung and colleagues 

of the Forest Research Institute, Kepong, 

Malaysia (KEP). It was impossible to acquire samples 

of all genera; Amyrea and Mareya were not included. 

Leaf roughness was noted for the adaxial and abaxial 

surfaces. 

The leaves were rehydrated in boiling water. Crosssections 

(15, 20, 25, or 30 mm thick) of small leaf 

samples were taken from the middle of the lamina 

with a Reichert sledge microtome. The sections 

were stained for 5 min with Etzold’s colour solution 

(solution of 0.01% basic fuchsin + 0.04% safranine 

O + 0.15% astrablue in 2% acetic acid) and mounted 

in glycerine–gelatine (Waldeck, Germany). 

© 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 445–457

Cuticular macerations were made by leaving leaf 

samples overnight at 60 °C in a mixture of 30% 

hydrogen peroxide and glacial (99–100%) acetic acid 

(1 : 1), staining for 3 h with Sudan IV 0.5% in alcohol 

70% heated to 40 °C, and mounting in glycerine– 

gelatine. Photographs were taken with a SIS Colorview 

1 digital camera. The frequency and size of the 

styloids and the druse-like or clustered crystals were 

observed with polarized light. 

Measurements were performed using AnalySIS 

docu software and, in general, 15 points were measured 

per specimen. Measurements were taken of the 

thickness of the leaves (measured in between the 

styloids), length of the styloids, thickness of the epidermis 

and cuticle, and frequency of the styloids. The 

frequencies of intact styloids were counted over a 

standard length (714 mm) of the lamina in polarized 

light. The frequencies were then standardized to a 

thickness of the cross-sections of 15 mm (for example, 

the frequency of a lamina, 30 mm thick, was divided 

by two). Most of the results are presented in Table 1 

(data on epidermis and cuticle thickness are not 

provided, see ‘Discussion’). 

The leaves used for scanning electron microscopy 

were dehydrated with alcohol 95% and acetone, air 

dried, coated with gold for 6 min using a Bal-Tec SCD 

005 sputter coater, studied with a JEOL JSM-5300 

scanning electron microscope, and photographed 

using the computer program SEMaFORE. The photographs 

were used to determine whether or not 

styloids protruded from the epidermis. 

The elements making up the crystal type were 

identified using a Philips XL20 equipped with an 

energy-dispersive X-ray analysis (EDAX) X-ray 

system (25 kV; working distance, 12 mm). The styloids 

were sputter coated with carbon using a Paar 

B50/200R carbon sputter. 

RESULTS 

GENERAL ANATOMY 

The following general leaf anatomical details are 

observed in the Claoxylinae (Table 1). 

Trichomes/papillae: In most species, trichomes are 

present, but no papillae are found. Five types of 

trichome can be distinguished. 

1. Thick-walled, straight to curved, unicellular, 

pointed slender hairs (Fig. 1; long hairs). 

2. Thick-walled, unicellular, curly hairs (C. coriaceolanatum, 

C. lutescens, and C. nubicola) (Fig. 4; 

Table 1; character 11). 

3. Relatively thin-walled, unicellular hairs that are 

less slender than types 1 and 2 and have blunt tips 

(Fig. 1; short hairs). 

LEAF ANATOMY OF CLAOXYLON AND ALLIES 447 

4. Two-armed, thick-walled, unicellular hairs 

(‘Malpighiaceous hairs’) with slender, pointed 

arms of unequal length (in a group of species from 

New Guinea and the Pacific: C. echinospermum, 

C. fallax, C. ledermannii, C. microcarpum, C. parvicoccum, 

C. paucinerve, C. putii, C. sandwicense, 

C. taitense, and C. vitiense) (Figs 3, 7; Table 1; 

character 11). In several species, the hairs are 

intermediate between types 1, 2, and 3, and 

possess short ‘second arm stubs’ (Fig. 2). 

5. Whereas types 1–4 have rather narrow hair bases, 

a fifth unicellular hair type occurring in Mercurialis 

has a very broad base and is larger in size. 

6. Lobanilia is the only genus with stellately bundled 

simple hairs of type 1 (Fig. 5; Table 1; character 

11). 

Stomata: All species have paracytic stomata (Fig. 3) 

that are almost exclusively restricted to the abaxial 

surface. Only a few species in Claoxylinae also have 

adaxial stomata that occur at lower density than 

abaxially. These are sometimes restricted to the epidermal 

areas overlying the veins (Table 1; character 

2). 

Cuticle: Cuticular striations are found in some 

species of Claoxylon, Micrococca, and Erythrococca. 

As reported by Kulshreshtha & Ahmad (1992), striations 

often run perpendicular to the pores around 

stomata. 

Hypodermis: The hypodermis is mainly lacking, but 

species in Claoxylon (Fig. 8; Table 1; character 1) 

possess a continuous hypodermis. 

Mesophyll: The mesophyll is uniformly dorsiventral 

(Fig. 7). The spongy tissue varies from compact 

(Fig. 7) to very lacunar. 

Epidermis: There is much variation in the outline of 

the anticlinal epidermal cell walls, often with differences 

between adaxial and abaxial cells. The abaxial 

cells have more sinuous anticlinal walls and the 

adaxial epidermis has straighter walls. The variation 

within and between species was not considered, 

because, in general, only one specimen per species 

was studied. 

CRYSTALS 

Most genera and species in the Claoxylinae possess 

styloids, a special type of crystal, which are long, 

slender, and sharply pointed (Figs 6, 7, 10). The 

X-rays showed that they are composed of calcium 

oxalate (in agreement with Pax & Hoffmann, 1931). 

Styloids are found in Claoxylon, Discoclaoxylon, 



Table 1. Observed and measured leaf anatomical characters of Claoxylinae 

Taxon 

Character 

1 2 3 4 5 6 7 8 9 10 11 

Claoxylon abbreviatum – – + + + 171 141 – 1.3 2 

Claoxylon albicans – – + + + 91 99 + 1.6 2 

Claoxylon brachyandrum (Teijsmann HB 10758) – – + + ? 180 121 – 7.6 3 

Claoxylon brachyandrum (Vriese & Teijsmann) – – +/– + + 92 85 – 4.3 3 

Claoxylon caerulescens – – +/– + + 108 63 – 0.6 1 

Claoxylon capillipes – – + + + 167 150 – 0.8 1 

Claoxylon carinatum – – + + + 85 121 + 1 

Claoxylon carolineanum – – + + + 147 133 – 0.9 1 

Claoxylon carrii – – + + + 193 123 – 1.3 2 

Claoxylon centinarium – – +/– + +/– 88 70 – 2.4 2 

Claoxylon colfsii – – + + + 100 122 + 1.6 2 

Claoxylon collenettei – – +/– + +/– 232 101 – 6.4 3 

Claoxylon coriaceolanatum – – +/– + +/? 163 66 – 3.7 3 C 

Claoxylon cuneatum – + + + + 105 79 – 3 

Claoxylon cuspidatum – – + + + 51 82 + 1.8 2 

Claoxylon dolichostachyum + – +/– + + 342 242 – 1 

Claoxylon echinospermum (A.C. Smith 7524) – – + + +/– 201 181 – 2.0 2 T 

Claoxylon echinospermum (A.C. Smith 7547) – – +/– + + 201 125 – 3.2 3 T 

Claoxylon ellipticum – – + + + 115 118 + 2.1 2 

Claoxylon erythrophyllum – – +/– + +/– 121 126 + 1.9 2 

Claoxylon euphorbioides – – + + + 122 133 + 1.6 2 

Claoxylon extenuatum – – + + +/– 57 60 + 1.0 2 

Claoxylon fallax – – +/– + +/– 256 174 – 2.2 2 T 

Claoxylon frutescens – – +/– + – 139 128 – 3.7 3 

Claoxylon gillisonii – – + + + 119 160 + 1.7 2 

Claoxylon glabrifolium – – +/– + +/– 121 103 – 1.6 2 

Claoxylon glandulosum + – + + –/+ 164 154 – 0.3 1 

Claoxylon goodenoviense – – + + + 135 125 – 1.3 2 

Claoxylon grandifolium – – + + + 118 107 – 0.2 1 

Claoxylon gymnadenum – – +/– + +/– 92 108 + 3.0 3 

Claoxylon hainanensis – – – + – 92 50 – 1 

Claoxylon helleri + – +/– + +/? 284 190 – 1.0 2 

Claoxylon hirsutellum – – +/– + + 82 117 + 3.2 3 

Claoxylon indicum – – +/– + + 99 118 + 3.0 3 

Claoxylon insulanum – – +/– + + 148 1229 – 4.0 3 

Claoxylon khasianum – – +/– + +/– 82 68 – ? 

Claoxylon kinabaluense – – + + + 136 122 – 2.4 2 

Claoxylon kingii – – +/– + ? 122 69 – 1 

Claoxylon ledermanii – – + + +/– 186 194 + 2.6 2 T 

Claoxylon longifolium (Blume 1395) – – + + + 92 77 – 2.0 2 

Claoxylon longifolium (Keßler PK 1895) – + + + + 132 98 – 3.7 3 

Claoxylon lutescens (NGF 32016) – – +/– + + 147 113 – 5.0 3 C 

Claoxylon lutescens (Endert 2396) – – +/– + +/? 132 103 – 7.5 3 C 

Claoxylon mananarense – – – + – 137 94 – 2.4 2 

Claoxylon marianum + – + + +/– 143 113 – 4.7 3 

Claoxylon microcarpum – – + + + 90 124 + 2.0 2 T 

Claoxylon monoicum – – + + +/– 236 193 – 0.3 

Claoxylon muscisilvae – – + + + 92 101 + 3.0 3 

Claoxylon nubicola – – +/– + + 316 124 – ? 1 C 

Claoxylon oliganthum – – – + – 283 103 – 1.0 2 

Claoxylon papuae – – + + + 150 142 – 2.3 2 


Table 1. Continued 

Taxon 


Character 

1 2 3 4 5 6 7 8 9 10 11 

Claoxylon parvicoccum – – + + + 179 158 – 3.0 3 T 

Claoxylon parviflorum – – +/– + ? 190 176 – 2.0 2 

Claoxylon paucinerve – – + + + 116 122 + 2.0 2 T 

Claoxylon physocarpum – – + + + 132 169 + 2.0 2 

Claoxylon platyphyllum – – +/– + –/? 192 114 – 3 

Claoxylon porphyrostemon +/– – – + – 217 74 – 3 

Claoxylon praetermissum – + + + + 134 120 – 2.5 2 

Claoxylon psilogyne – – + + +/– 75 101 + 1.3 2 

Claoxylon purpureum – – – + – 112 70 – 1 

Claoxylon putii – – – + – 85 45 – 1 

Claoxylon racemiflorum + – + + + 178 143 – 3.0 3 

Claoxylon salicinum – – – + – 125 112 – 2.9 2 

Claoxylon salomonense – – + + +/– 158 145 – 4.3 3 

Claoxylon sanctaecrucis – – + + –/+ 95 103 + 1.2 2 

Claoxylon sandwicense – – + + + 166 104 – 1.0 2 T 

Claoxylon scabratum – – + + + 233 171 – 2.7 2 T 

Claoxylon stapfianum – – + + + 151 144 – 1.3 2 

Claoxylon subbullatum – – + + – 157 97 – 1 

Claoxylon subviride – + + + + 179 102 – 4.3 3 

Claoxylon taitense – – +/– + ? 206 86 – 3 T 

Claoxylon tenerifolium (Pullen 6879) – – – + – 152 116 – 5.0 3 

Claoxylon tenerifolium (Stocker 903) – – – + +/– 259 110 – 1.0 2 

Claoxylon tenuiflorum – – + + + 140 160 + 3.3 3 

Claoxylon tetracoccum – + +/– + ?/– 114 87 – 3 

Claoxylon tumidum – – + + +/– 85 124 + 2.0 2 

Claoxylon velutinum – – +/– + –/+ 113 107 – 3 

Claoxylon vitiense – – +/– + +/? 143 97 – 3 T 

Claoxylon wallichianum – – +/– + – 104 94 – 1 

Claoxylopsis perrieri – + +/– – X 47 0 

Discoclaoxylon hexandrum (Andoh 5690) – – – + – 152 138 – 1 

Discoclaoxylon hexandrum (Versteegh 741) – – – + – 202 ? 1 

Discoclaoxylon hexandrum (Zenker 2790) – – +/– + +/– 148 140 – 1.0 2 

Erythrococca anomale – – – + – 150 94 – 8.4 3 

Erythrococca atrovirens – – – + – 112 91 – 3.1 3 

Erythrococca bougensis – – – + – 137 120 – 2.7 2 

Erythrococca columnaris – – – + – 84 129 + 1.5 2 

Erythrococca fischeri – – – + – 87 49 – 0.4 1 

Erythrococca kirkii – + – + – 143 113 – 2.7 2 

Erythrococca trichogyne (Maas Geesteranus 5245) – – +/– + – 144 126 – 3.0 3 

Erythrococca trichogyne (Stolz 1556) – – – + – 97 68 – 1.2 2 

Erythrococca welwitschiana (Zenker 3913) – – +/– + – 100 90 – 1 

Erythrococca welwitschiana (Zenker 4912) – – +/– + +/– 123 116 – 4.0 3 

Lobanilia luteobrunnea* – – ? + – ? ? S 

Mercurialis annua – – – – X 0 0 0.0 

Mercurialis jordani – – – – X 0 0 0.0 

Mercurialis leiocarpa – – – – X 0 0 0.0 

Mercurialis ovata – – – – X 0 0 0.0 

Micrococca lancifolia – – + + + 161 151 – 1.6 2 

Micrococca malaccensis – – – – X 0 0 0.0 

Micrococca mercurialis (SF 39822) – – + + + 120 132 + 3.0 3 



Table 1. Continued 

Taxon 

Erythrococca, Lobanilia, and all but one species of 

Micrococca. Micrococca malaccensis lacks styloids 

(Table 1; character 4). The crystals are absent in 

Claoxylopsis and Mercurialis (Table 1). The styloids 

are positioned more or less perpendicular to the leaf 

surface (strongly oblique crystals also occur), often 

running from cuticle to cuticle (Fig. 7). When they are 

short, they are present in the adaxial or abaxial part 

of the mesophyll. 

In Erythrococca, the leaves generally feel smooth 

and the styloids do not protrude from the surface 

(Figs 11, 12) with two exceptions: E. hirta feels rough, 

but has no protruding styloids; E. welwitschiana only 

feels rough adaxially where styloids protrude somewhat 

(Table 1; characters 3 and 5). In dried leaves of 

Erythrococca, the epidermis usually wrinkles around 

the styloids, whereby the styloids act as a kind of tent 

pole elevating the epidermis into small pyramids 

(Fig. 11). Discoclaoxylon also has nonprotruding or 

only very slightly protruding styloids (tip only; 

Fig. 12) in leaves that are smooth to the touch. 

In Claoxylon and Micrococca, the leaves generally 

feel rough and the styloids usually penetrate through 

the epidermis (Figs 6, 10; Table 1; characters 3 and 5), 

although this is not always the case. Some species feel 

smooth and have no protruding styloids (C. oliganthum, 

C. porphyrostemon, C. purpureum, C. putii, 

and C. tenerifolium), despite the fact that styloids are 

present. In some species, the leaves feel (partly) 

smooth, either because the styloids protrude at very 

low density (C. hainanensis) or on one side only 

(C. hillii). 

The density of the styloids is variable between 

species, but a correlation with roughness is not 

Character 

1 2 3 4 5 6 7 8 9 10 11 

Micrococca mercurialis (Stolz 1207) – – + + + 153 131 – 0.8 1 

Micrococca oligandra – – + + + 125 112 – 3.5 3 

Micrococca wightii – – + + + 180 126 – 3.0 3 

Character 1, hypodermis (+, present; +/–, only locally developed); character 2, stomata also present on adaxial surface (+) 

or restricted to abaxial epidermis (–); character 3, leaf roughness (–, smooth; +/–, unclear; +, rough; adaxial/abaxial); 

character 4, styloids (–, absent; +, present); character 5, protrusion of styloids (–, not protruding; +, protruding; –/+ or +/–, 

protruding either adaxially or abaxially; X, styloids absent); character 6, lamina thickness in mm; character 7, length of 

styloids in mm; character 8, relative length of styloids (–, shorter than leaf thickness; +, longer); character 9, styloid 

frequency (number of intact styloids over length of 714 mm standardized to a section with a thickness of 15 mm); character 

10, styloid frequency classes (1, frequency < 1; 2, 1 < frequency < 3; 3, frequency 3); character 11, presence of special hair 

types (normal straight unicellular hairs not noted) (C, curly unicellular hairs; S, unicellular hairs in stellate bundles; T, 

two-armed hairs). 

*The quality of the microscopic slide was too poor to see a good transverse section, and thus only qualitative characters 

are noted. 

directly evident. The smooth Claoxylon species may 

have a high density of styloids (for example, C. porphyrostemon 

feels smooth, but has density class 3; 

Table 1), and rough species may have few styloids 

(for example, C. crassifolium feels very rough, but has 

density class 1; Table 1). The length of the crystals is 

variable between the species (Table 1; character 7). In 

Claoxylon, there is also no correlation between roughness 

and the length of the styloids and/or the thickness 

of the leaf blade. Claoxylon caerulescens has very 

short styloids (63 mm on average), a thick leaf lamina 

(108 mm), and feels rough, whereas C. carinatum has 

styloids (121 mm) much longer than the leaf blade 

thickness (85 mm in the partly rehydrated state), but 

is only slightly rough. Both species have a low crystal 

density. 

In addition to the styloid crystals, there are also 

druses and/or clustered crystals present in most 

species of Claoxylon, Claoxylopsis, Erythrococca, 

Lobanilia, Mercurialis, and Micrococca (no distinction 

could be made between these two intergrading types, 

druses being the more regularly star-shaped version 

of clustered crystals). There is some variation in the 

location of druses or clusters in the leaf. In some 

species, they are only found near the veins, but, in 

other species, they are also found throughout the 

chlorenchyma of the mesophyll. When the druses/ 

clusters are present in the chlorenchyma, they are 

also present in the bundle sheaths of the veins, and 

sometimes also in the phloem of the vascular bundles. 

Moreover, in some species, styloids gradually intergrade 

with much shorter, solitary, nonpointed crystals 

that range to diamond-shaped or rhombic. The abundance 

of these crystal types varies widely. 



Figures 1–6. Figures 1–5. Various hair types present in Claoxylon and Lobanilia. Figure 1. Claoxylon indicum with type 

1 (thick-walled, straight to curved, unicellular, pointed, slender hairs) and type 3 (relatively thin-walled, unicellular hairs 

that are less slender than type 1 with blunt tips) hairs on abaxial surface. Scale bar, 200 mm. Figure 2. Claoxylon 

carinatum, abaxial surface, unicellular hair with short second arm ‘stub’. Scale bar, 50 mm. Figure 3. Abaxial view of 

C. echinospermum with type 4 hairs (‘Malpighiaceous’, two-armed); note the paracytic stomata. Scale bar, 50 mm. Figure 4. 

Claoxylon coreaceolanatum, abaxial surface, with type 2 hairs (thick-walled, unicellular, curly). Scale bar, 50 mm. Figure 5. 

Lobanilia luteobrunnea with stellately fascicled hairs on the abaxial surface. Scale bar, 200 mm. Figure 6. Protruding 

styloid crystal on the adaxial surface of C. subviride. Scale bar, 10 mm. 



Figures 7–12. Styloids in Claoxylon and Erythrococca. Figure 7. Transverse section of C. vitiense showing a styloid on the 

right penetrating the upper epidermis, and, on the left, a type 4 ‘Malpighiaceous’ two-armed hair. Scale bar, 50 mm. 

Figure 8. Transverse section through a leaf of C. racemiflorum showing the hypodermis and two styloids, which probably 

penetrated the upper epidermis and cuticle in vivo. Scale bar, 50 mm. Figure 9. Upper leaf surface of C. parvicoccum 

showing two sites (arrows) where styloids probably penetrated the epidermis in vivo, but in this case did not perforate 

the cuticle. Scale bar, 50 mm. Figure 10. Adaxial leaf surface of C. fallax showing the protrusion of the styloids after 

drying; this leaf feels rough. Scale bar, 50 mm. Figure 11. Adaxial leaf surface of dried leaf of E. columnaris. The styloids 

cause tent-like elevations that generally do not penetrate the epidermis and cuticle. This leaf is smooth to the touch. Scale 

bar, 100 mm. Figure 12. Detail of Figure 11, showing tent-like elevation with modified cuticle at the apex. Scale bar, 10 mm. 


DISCUSSION 

The presence of styloids in the leaves of this group of 

genera seems to be unique in Euphorbiaceae. It is 

also a rare phenomenon in other dicotyledonous families. 

Metcalfe & Chalk (1983) listed 26 families in 

which styloids occur, usually only in a small minority 

of the genera (cf. Metcalfe & Chalk, 1950). Large 

styloids, sometimes referred to as ‘megastyloids’, such 

as the largest styloids in Claoxylon and its relatives, 

are even less common. 

It may seem obvious that styloids will cause 

surface roughness, but this is not self-evident. A 

genus such as Mercurialis lacks styloids and has 

smooth leaves. On the other hand, Claoxylopsis also 

lacks styloids, but the leaves feel slightly rough. 

Claoxylon species possess styloids and usually feel 

rough (exceptions occur; for example, C. oliganthum 

is smooth), but Erythrococca and Discoclaoxylon 

(styloids present) are generally smooth to the touch. 

The leaf surface texture of Lobanilia luteobrunnea is 

entirely determined by its dense indumentum, and 

cannot be compared with the less hairy Claoxylinae. 

The difference in roughness is caused by the fact 

that, in dried leaves, the styloids in Claoxylon and 

Micrococca perforate the epidermis and protrude 

from it (Figs 6, 10), whereas, in Erythrococca and 

Discoclaoxylon, the styloids do not or only very 

slightly perforate the epidermis, not sufficiently to 

cause any roughness to the touch (Figs 11, 12). 

Usually, the epidermis remains intact and folds over 

the tip of the crystals (Fig. 11). Thus, perforating 

styloids give rise to rough leaves, whereas leaves 

with nonperforating styloids (even though these can 

be much longer than the dry leaf thickness) generally 

remain smooth. 

Some exceptions still occur: there are several 

smooth-leaved Claoxylon species (Table 1) and several 

(somewhat) rough Erythrococca species. These are 

difficult to explain, because the roughness is not 

caused by the length of the part of the styloids that 

extends beyond the cuticle (as suggested by Pax & 

Hoffmann, 1931), or by the frequency of the styloids. 

Smooth-leaved Claoxylon species sometimes have 

longer crystals than many species with rough leaves, 

but they all have crystals that are much shorter than 

the leaf thickness. However, many rough-leaved 

species also have crystals much shorter than the leaf 

thickness. This may be explained by the fact that the 

sharply pointed styloids may more easily perforate 

the epidermis than the mesophyll tissues. Thus, in 

some species with thick leaves, the short styloids are 

able to perforate the leaves, but in other species they 

are not. Another explanation may be that differences 

in pressure during the drying process may result in 

perforation or not. 


Several of the figures (Figs 8, 9, 12) indicate that 

the styloid-containing cells are surrounded by modified 

epidermal cells, suggesting that styloids may 

already penetrate the epidermis and cuticle slightly 

in vivo. This could not be confirmed with living 

material. Perforation of the cuticle in vivo is 

counter-intuitive, because it would make the leaves 

vulnerable to microbial infection and disease. All 

fresh leaves of Claoxylon probably feel smooth. This 

has been confirmed for C. longifolium by the KEP 

herbarium staff (Richard Chung, Forest Research 

Institute, Kepong, Malaysia, pers. comm.), who 

checked trees in the arboretum. The leaves of fresh 

C. longifolium, whether growing in the sun or shade, 

are smooth; the leaves become rough only on drying. 

Seemingly, this is the case with most Claoxylon and 

Micrococca species. However, further research on the 

development of styloids and their interaction with 

epidermal cells and the cuticle in living material of 

several species is clearly needed. 

The fact that dried leaves of Micrococca generally 

feel rough was a surprise. In this study, mainly 

African species were included. Two species from Asia 

were also examined. One was the rough-leaved 

M. mercurialis (resembling Claoxylon, but differing in 

its small leaves and herbaceous habit). Two Micrococca 

species are endemic to the Malay Peninsula: 

M. johorica and M. malaccensis (Sagun & van 

Welzen, 2002). Only M. malaccensis was included in 

this study and this species lacks styloids altogether 

(M. johorica was not included). Both species were 

described by Airy Shaw (1971), who expressed doubts 

about their inclusion in Micrococca. The absence of 

styloids in at least M. malaccensis suggests that this 

species might have to be transferred to another 

genus, but a likely candidate is not obvious. 

It is still unclear why the styloids penetrate the 

cuticle in Claoxylon and Micrococca, but not in the 

other genera. We attempted to determine whether 

there was a difference in the epidermis/cuticle thickness 

between the genera, but no difference was found; 

moreover, within Claoxylon, cuticular penetration 

occurred through a wide range of thicknesses of both 

periclinal cell walls and cuticles. The styloids in 

all genera have a similar appearance, with sharp, 

oblique, angular tips that look very suitable for 

cutting through the cuticle (Fig. 10). Therefore, the 

absence of epidermal penetration (or only slight penetration; 

Figs 9, 12) by styloids in Erythrococca and 

Discoclaoxylon is curious. 

A few species possess a hypodermis (Table 1; character 

1). It is not clear whether, ontogenetically, this 

layer should be considered as a multiple epidermis or 

a true hypodermis. Cuticular ornamentations are 

often observed. These are sometimes caused by the 

styloids, because the surfaces are wrinkled around 



the tip of the styloids in Erythrococca (Figs 11, 12), 

Discoclaoxylon, and some species of Claoxylon and 

Micrococca. Striations perpendicular to the stomatal 

pore also occur frequently around the paracytic 

stomata, as noted by Kulshreshtha & Ahmad (1992). 

The gelatinization of the epidermis (Raju & Rao, 

1977) could not be confirmed in this study. 

Several species are represented by two or three 

accessions. The results show that variability is 

present in the leaf thickness, styloid length and 

density, and, to a lesser degree, protrusion of the 

styloids. The largest differences are found in E. welwitschiana 

and M. mercurialis, where the density of 

the styloids differs between class 1 and 3, and one 

specimen of E. welwitschiana has slightly protruding 

styloids instead of nonprotruding ones. However, the 

variability is not of a sufficient magnitude to affect 

our conclusions. 

A limited number of species possess curly (three 

species) and two-armed (11 species) hairs (Table 1; 

character 11). Most of these are classified in Claoxylon 

section Indica Pax & K.Hoffm., some in Claoxylon 

section Affinia Pax & K.Hoffm., and some in both. Only 

C. sandwicense is in a different (monotypic) section: 

Claoxylon section Gymnoclaoxylon Müll.Arg. The sectional 

classification of Pax & Hoffmann (1914) does not 

appear to be reliable, because several species can be 

classified in more than one section (for example, C. microcarpum 

and C. paucinerve), and authors of new 

species usually refrain from placing them in one of the 

sections. Still, it is possible that the exceptional hair 

types represent synapomorphies. The species with 

two-armed hairs all occur in New Guinea and the West 

Pacific up to Hawaii. The species with curly hairs are 

only found in New Guinea at higher altitudes. 

Species in Claoxylon section Luteobrunnea Pax & 

K.Hoffm. were placed in a separate genus (Lobanilia) 

and subtribe (Lobaniliinae) by Radcliffe-Smith (1989) 

because of the simple hairs in stellate bundles (Fig. 5). 

The presence of styloids in Lobanilia and Claoxylinae 

confirms the results of the phylogenetic study by 

Wurdack et al. (2005), in which Lobanilia is part of the 

Claoxylinae clade. The molecular study and our anatomical 

results show that Lobaniliinae should be 

united with Claoxylinae. Claoxylon, Discoclaoxylon, 

Erythrococca, Lobanilia, and Micrococca all possess 

styloids. This group also forms a subclade in the 

molecular study of Wurdack et al. (2005). The styloids 

are a synapomorphy for this group, which may be 

referred to as Claoxylinae s.l. We can confirm that 

Claoxylopsis and Mercurialis are not part of this 

restricted group. Claoxylopsis was placed tentatively 

in the Claoxylinae by Webster (1994). Nowicke & 

Takahashi (2002) showed the pollen to be of a different 

type than that of the Claoxylinae, indicating that it 

should be classified in another group of Euphorbiaceae. 

Mercurialis, with another hair type and a lack of 

styloids, is indeed different from the Claoxylinae s.l. 

It was included in this study because it was the local 

outgroup/sister to the Claoxilinae in the molecular 

phylogenetic study by Wurdack et al. (2005). Neither 

this study, nor that of Wurdack et al. (2005), discusses 

or changes the taxonomic position of Mercurialis, 

which is maintained in the subtribe Mercurialinae. 

In conclusion, the leaf roughness in Claoxylinae 

s.l. (including Lobaniliinae) is caused by protruding 

styloid crystals. The presence of the styloids is a good 

synapomorphy for a monophyletic subclade of the 

Claoxylinae (Claoxylon, Discoclaoxylon, Erythrococca, 

Lobanilia, and Micrococca) as circumscribed by 

Webster (1994), Radcliffe-Smith (2001), and Wurdack 

et al. (2005). 

ACKNOWLEDGEMENTS 

We wish to thank the curators of the herbaria L and 

WAG for supplying us with leaf samples. Richard 

Chung and colleagues (Forest Research Institute, 

Kepong, Malaysia) are thanked for checking the 

roughness of fresh leaves of Claoxylon. Professor H. 

Sieghardt, W. Klepal, and D. Gruber (University of 

Vienna, Austria) are thanked for the use of the EDAX 

system. We would also like to thank an anonymous 

reviewer for extremely useful comments. 

REFERENCES 

Airy Shaw HK. 1971. Notes on Malesian and other Asiatic 

Euphorbiaceae. CXXXVII. Two new species of Micrococca 

Benth. from Malaya. Kew Bulletin 25: 524–526. 

Airy Shaw HK. 1972. The Euphorbiaceae of Siam. Kew 

Bulletin 26: 233–234. 

Airy Shaw HK. 1980. The Euphorbiaceae of New Guinea. 

Kew Bulletin Additional Series 8: 1–243. 

Carey G. 1938. Comparative anatomy of leaves from species 

in two habitats around Sydney. Proceedings of the Linnean 

Society of New South Wales 63: 439–450. 

Govaerts R, Frodin DG, Radcliffe-Smith A. 2000. World 

checklist and bibliography of Euphorbiaceae 1 (with Pandaceae). 

Kew: Royal Botanical Gardens. 

de Jussieu A. 1824. De Euphorbiacearum generibus medicisque 

earumdem viribus tentamen. Paris: Didot, 43. 

Kulshreshtha K, Ahmad KJ. 1992. Cuticular ornamentations 

in some genera of Euphorbiaceae. Feddes Repertorium 

103: 5–6, 317–326. 

Metcalfe CR, Chalk L. 1950. Anatomy of the dicotyledons, 

Vol. 2. Oxford: Clarendon Press. 

Metcalfe CR, Chalk L. 1979 & 1983. Anatomy of the dicotyledons, 

Vol.1&2,2ndedn.Oxford: Clarendon Press. 

Nowicke JW, Takahashi WM. 2002. Pollen morphology, 

exine structure and systematics of Acalyphoideae (Euphorbiaceae), 

Part 4: Tribes Acalypheae pro parte (Erythrococca, 

Claoxylon, Claoxylopsis, Mareya, Mareyopsis, Discoclaoxy- 


lon, Micrococca, Amyrea, Lobanilia, Mallotus, Deuteromallotus, 

Cordemoya, Cococceras, Trewia, Neotrewia, Rockinghamia, 

Octospermum, Acalypha, Lasiococca, Spathiostemon, 

Homonoia), Plukenetieae (Haematostemon, Astrococcus, 

Angostyles, Romanoa, Eleutherostigma, Plukenetia, Vigia, 

Cnesmone, Megistostigma, Sphaerostylis, Tragiella, 

Platygyna, Tragia, Acidoton, Pachystylidium, Dalechampia), 

Omphaleae (Omphalea), and discussion and summary of the 

complete subfamily. Review of Paleobotany and Palynology 

121: 231–336. 

Pax F, Hoffmann K. 1914. Euphorbiaceae-Acalypheae- 

Mercurialinae. In: Engler A, ed. Das Pflanzenreich IV. 147. 

vii. Leipzig: Wilhelm Engelmann, 100–131. 

Pax F, Hoffmann K. 1931. Euphorbiaceae. In: Engler A, 

Harms H, eds. Die natürlichen Pflanzenfamilien, 2nd edn., 

Part 19c. Leipzig: Wilhelm Engelmann, 11–233. 

Perry BA. 1943. Chromosome number and phylogenetic 

relationships in the Euphorbiaceae. American Journal of 

Botany 30: 527–543. 

Punt W. 1962. Pollen morphology of the Euphorbiaceae with 

special reference to taxonomy. Wentia 7: 1–116. 

Radcliffe-Smith A. 1989. Notes on Madagascan Euphorbiaceae 

II. Claoxylon Sect. Luteobrunnea. Kew Bulletin 44: 

333–340. 

Radcliffe-Smith A. 2001. Genera Euphorbiacearum. Kew: 

Royal Botanical Gardens. 

Raju VS, Rao PN. 1977. Variation in the structure and 

development of foliar stomata in the Euphorbiaceae. Botanical 

Journal of the Linnean Society 75: 69–97. 

Sagun VG, van Welzen PC. 2002. Revision of the Malesian 

species of Micrococca (Euphorbiaceae). Blumea 47: 149–155. 

Solereder H. 1908. Systematische Anatomie der Dicotyledonen. 

Ergänzungsband, 286. Stuttgart: Ferdinand Enke. 

Webster GL. 1975. Conspectus of a new classification of the 

Euphorbiaceae. Taxon 24: 593–601. 

Webster GL. 1994. Synopsis of the genera and suprageneric 

taxa of Euphorbiaceae. Annals of the Missouri Botanical 

Garden 81: 33–144. 

van Welzen PC. 2005. Claoxylon. In: Chayamarit K, van 

Welzen PC, eds. Flora of Thailand, Vol. 8, Part 1. Bangkok: 

The Forest Herbarium, 159. 

Wurdack KJ, Hoffmann P, Chase MW. 2005. Molecular 

phylogenetic analysis of uniovulate Euphorbiaceae (Euphorbiaceae 

sensu stricto) using plastid rbcL and trnl-F DNA 

sequences. American Journal of Botany 92: 1397–1420. 

APPENDIX 

LIST OF SPECIMENS SAMPLED FOR THE LEAF 

ANATOMICAL STUDIES 

All material in L unless stated otherwise. The 

full label information is available at http:// 

www.nationaalherbarium.nl. 

Claoxylon abbreviatum Airy Shaw: Indonesia, 

Sumatra, Junghuhn 529 (L 0164220). 

Claoxylon albicans (Blanco) Merr.: Philippines, 

Luzon, Vanoverbergh 188 (L 0164429; formerly 

C. elongatum Merr.). 


Claoxylon brachyandrum Pax & K.Hoffm.: Indonesia, 

Lesser Sunda Islands, Teijsmann HB 10758 

(L 0164321); Indonesia, Moluccas, Banda, Vriese & 

Teijsmann s.n. (L 0164325). 

Claoxylon caerulescens Ridl.: Christmas Island (south 

of Java), B.A. Mitchell 43 (L 0164334). Treated by 

Govaerts et al. (2000) as a synonym of C. indicum, but 

the specimens of Christmas Island dry purplish, 

whereas C. indicum dries greenish, and, within 

Claoxylon, this difference is generally used for species 

recognition. 

Claoxylon capillipes Airy Shaw: Papua New Guinea, 

LAE (Katik) 62269 (L 0164341). 

Claoxylon carinatum Airy Shaw: Indonesia, Kalimantan 

Timur, Endert 4681 (L 0164356). 

Claoxylon carolineanum Pax & K.Hoffm.: Papua 

New Guinea, Bougainville, Schodde & Craven 3930 

(L 0164365). 

Claoxylon carrii Airy Shaw: Papua New Guinea, Carr 

15209 (L 0164368). 

Claoxylon centinarium Koidz.: Japan, Bonin Island, 

Yamazaki 58 (L 0437802). 

Claoxylon colfsii Airy Shaw: Indonesia, Lesser Sunda 

Islands, Colfs 246 (L 0244744). 

Claoxylon collenettei Riley: French Polynesia, Society 

Islands, Rapa, H.St.John & Fosberg 15295 (L 

0164384). 

Claoxylon coriaceolanatum Airy Shaw: Papua New 

Guinea, Takeuchi 10519 (L 0446893). 

Claoxylon cuneatum J.J.Sm.: Indonesia, Papua, Aet 

18 (L 0164403). 

Claoxylon cuspidatum J.J.Sm.: Indonesia, Kalimantan, 

Korthals s.n. (L 0164407). 

Claoxylon dolichostachyum Cordem.: Reunion, Coode 

et al. 5152 (L 0164414). 

Claoxylon echinospermum Müll.Arg.: Fiji, Ovalau, 

A.C. Smith 7524 (L 0270253; formerly under C. sitibundum 

Croizat); idem, A.C. Smith 7547 (L 0164416). 

Claoxylon ellipticum Merr.: Philippines, Palawan, 

PNH (Mendoza & Cordero ) 91344 (L 0164423). 

Claoxylon erythrophyllum Miq.: Indonesia, Lesser 

Sunda Islands, Kostermans & Wirawan 418 (L 

0164442). 

Claoxylon euphorbioides (Elmer) Merr.: Philippines, 

Sibuyan, Elmer 12424 (L 0059811). 

Claoxylon extenuatum Airy Shaw: Papua New 

Guinea, Bougainville, NGF (Lavarack & Ridsdale) 

31303 (L 0059809). 

Claoxylon fallax Müll.Arg.: Fiji, Vanua Levu, A.C. 

Smith 6683 (L 0164471). 

Claoxylon frutescens Airy Shaw: Indonesia, Sulawesi, 

Koorders 16835 (L 0164477). 

Claoxylon gillisonii Airy Shaw: Vanuatu, Malakula, 

Gillison RSNH 3540 (L 0164480). 

Claoxylon glabrifolium Miq.: Indonesia, Java, Raap 

741 (L 0164484). 



Claoxylon glandulosum Boivin ex Baill.: Reunion, 

Coode & Cadet 4978 (L 0164498). 

Claoxylon goodenoviense Airy Shaw: Papua New 

Guinea, Brass 24844 (L 0016092). 

Claoxylon grandifolium (Poir.) Müll.Arg.: Mauritius, 

Sieber Fl. Mauritius II 184 (L 0164397; formerly 

C. crassifolium Baill.). 

Claoxylon gymnadenum Airy Shaw: Papua New 

Guinea, Bougainville, Craven & Schodde 273 (L 

0164503). 

Claoxylon hainanensis Pax & K.Hoffm.: China, 

Hainan, C.I. Lei 521 (L 0164504). 

Claoxylon helleri Sherff: USA, Hawaii, Kauai, Heller 

2878 (L 0164505). Govaerts et al. (2000) considered 

this name to be a synonym of C. sandwicense. Kept 

separate because this specimen lacks T-hairs (present 

in C. sandwicense). 

Claoxylon hirsutellum Airy Shaw: Indonesia, Kalimantan, 

Kostermans 12999 (L 0016093). 

Claoxylon indicum (Reinw. ex Blume) Hassk. (C. polot 

(Burm.f.) Merr.): Malaysia, Perlis, Ogata 10289 

(L 0164924). 

Claoxylon insulanum Müll.Arg.: New Caledonia, 

McKee 15873 (L 0164514). 

Claoxylon khasianum Hook.f.: India, Assam, J.D. 

Hooker & T. Thomson s.n. (L 0164532); idem, Masters 

s.n. (L 0164531). 

Claoxylon kinabaluense Airy Shaw: Malaysia, Sabah, 

W.L.Chew, Corner & Stainton RSNB 641 (L 0016094). 

Claoxylon kingii Hook.f.: Malaysia, Perak, KEP 

(Symington) 25726 (L 0164538). 

Claoxylon ledermannii Airy Shaw: Papua New 

Guinea, LAE (Katik) 62210 (L 0164543). 

Claoxylon longifolium (Blume) Endl.: Indonesia, 

Java, Blume 1395 (L 0164672); Malaysia, Selangor, 

KEP FRI (R.K.C. Chung) 5100 2; Indonesia, Kalimantan, 

P.J.A. Keßler et al. PK 1895 (L 0491530). 

Claoxylon lutescens Pax & K.Hoffm.: Indonesia, 

Lesser Sunda Islands, Elbert 2396 (L 0164767); 

Papua New Guinea, NGF (Frodin) 32016 (L 

0164771). 

Claoxylon mananarense Leandri: Madagascar, 

d’Alleizette s.n. xi.1905 (L 0158010). 

Claoxylon marianum Müll.Arg.: Micronesia, Mariana 

Islands, Guam, Moran 4673 (L 0164798). 

Claoxylon microcarpum Airy Shaw: Papua New 

Guinea, LAE (Essig & Lelean) 55024 (L 0164804). 

Claoxylon monoicum Baill.: Madagascar, Lam & 

Meeuse 5982 (L 0164827). 

Claoxylon muscisilvae Airy Shaw: Papua New 

Guinea, NGF (Womersley & Sleumer) 1402 1 (L 

0164829). 

Claoxylon nubicola Airy Shaw: Papua New Guinea, 

LAE (Vinas & Veldkamp) 59824 (L 0164835). 

Claoxylon oliganthum Airy Shaw: Thailand, Larsen 

et al. 30841 (L 0164536). 

Claoxylon papuae Airy Shaw: Papua New Guinea, 

Brass 22802 (L 0164860). 

Claoxylon parvicoccum Croizat: Fiji, Ngau, A.C. 

Smith 7848 (L 0164865). 

Claoxylon parviflorum A.Juss.: Reunion, Anonymous 

662 (L 0164873). 

Claoxylon paucinerve Airy Shaw: Papua New Guinea, 

M.S. Clemens 858 (L 0164877). 

Claoxylon physocarpum Airy Shaw: Indonesia, 

Sumatra, de Wilde & de Wilde-Duyfjes 14449 

(L 0164880). 

Claoxylon platyphyllum Airy Shaw: Papua New 

Guinea, UPNG (Frodin & Hallpike ) 711 (L 0016121). 

Claoxylon porphyrostemon Airy Shaw: Papua New 

Guinea, Hoogland & Pullen 5342 (L 0016122). 

Claoxylon praetermissum Airy Shaw: Malaysia, 

Sabah, SAN (J. Singh) 26347 (L 0270177). 

Claoxylon psilogyne Airy Shaw: Vanuatu, Tanna, P.S. 

Green RSNH 1242 (L 0270187). 

Claoxylon purpureum Merr.: Philippines, Luzon, PNH 

(Alcasid) 1898 (L 0270197). 

Claoxylon putii Airy Shaw: Thailand, Put 3860 

(L 0164861). 

Claoxylon racemiflorum A.Juss. ex Baill.: Reunion, 

Coode, Richardson & Bosser 5231 (L 0270212). 

Claoxylon salicinum Airy Shaw: Malaysia, Sabah, 

J. Clemens & M.S. Clemens 28529 (L 0270215). 

Claoxylon salomonense Airy Shaw: Papua New 

Guinea, Brass 24357 (L 0270218). 

Claoxylon sanctaecrucis Airy Shaw: Solomon Islands, 

Santa Cruz, BSIP (Mauriasi et al.) 16745 (L 

0016133). 

Claoxylon sandwicense Müll.Arg.: USA, Hawaii, 

Hawaii, Herbst & Spence 5473 (L 0270223). 

Claoxylon scabratum (Pax & K.Hoffm.) Airy Shaw: 

Papua New Guinea, Schodde 2238 (L 0270250). 

Claoxylon stapfianum Airy Shaw: Malaysia, Sabah, 

J. Clemens & M.S. Clemens 34146 (L 0270260). 

Claoxylon subbullatum Airy Shaw: Malaysia, Sabah, 

Chew & Corner RSNB 4659 (L 0016126). 

Claoxylon subviride Elmer: Philippines, Mindoro, 

PNH (Conklin) 19017 (L 0270268). 

Claoxylon taitense Müll.Arg.: French Polynesia, 

Tahiti, Florence 8701 (L 0445421). 

Claoxylon tenerifolium (Baill.) F.Muell.: Papua New 

Guinea, Pullen 6879 (L 0270287); Australia, Queensland, 

Stocker 903 (L 0164509; formerly under 

C. hillii Benth.). 

Claoxylon tenuiflorum Airy Shaw: Indonesia, 

Sumatra, de Wilde & de Wilde-Duyfjes 18131 (L 

0016134). 

Claoxylon tetracoccum Airy Shaw: Indonesia, Papua, 

BW (Schram) 5980 (L 0016136). 

Claoxylon tumidum J.J.Sm.: Papua New Guinea, 

NGF (Streimann & Katik) 28892 (L 0270333). 

Govaerts et al. (2000) treated this name as a synonym 


of C. cuneatum, but Airy Shaw (1980), in the most 

recent revision of Euphorbiaceae for New Guinea, still 

accepted both species. 

Claoxylon velutinum J.J.Sm.: Indonesia, Kalimantan, 

Amdjah 150 (L 0016129). 

Claoxylon vitiense Gillespie: Fiji, Viti Levu, A.C. 

Smith 8925 (L 0270363). 

Claoxylon wallichianum Müll.Arg.: Malaysia, 

Penang, Sinclair SF 39270 (L 0270368). 

Claoxylopsis perrieri Leandri: Madagascar, 

d’Alleizette 6494b (L 0270592). 

Discoclaoxylon hexandrum (Müll.Arg.) Pax & 

K.Hoffm.: Cameroon, Andoh 5690 (WAG); idem, 

Versteegh & den Outer 741 (WAG); idem, Zenker 

2790 (L 0270184; formerly Claoxylon preussii Pax). 

Erythrococca anomale (Juss. ex Poir.) Prain: Ivory 

Coast, Leeuwenberg 3271 (L 0025667). 

Erythrococca atrovirens (Pax) Prain var. flaccida 

(Pax) Radcl.-Sm.: Ivory Coast, d’Alleizette 6494 (L 

0291521). 

Erythrococca bongensis Pax: Kenya, Maas Geesteranus 

4932 (L 0025669). 

Erythrococca columnaris (Müll.Arg.) Prain: Zaire, 

Allouette s.n. (Hb. d’Alleizette) (L 0291522). 

Erythrococca fischeri Pax: Rwanda, Bouxin 1172 (L 

0445881). 

Erythrococca kirkii Prain: Kenya, Hildebrandt 2039 

(L 0025673). 

Erythrococca trichogyne (Müll.Arg.) Prain: Kenya, 


Maas Geesteranus 5245 (L 0025671; formerly under 

E. hirta Pax); Tanzania, Stolz 1556 (L 0025674; 

formerly under E. stolziana Pax & K.Hoffm.). 

Erythrococca welwitschiana (Müll.Arg.) Prain: Cameroon, 

Zenker 3912 (L 0270369); idem, Zenker 4912 

(L 0291524). 

Lobanilia luteobrunnea (Baker) Radcl.-Sm.: Madagascar, 

d’Alleizette s.n. (L 0164766). 

Mercurialis annua L.: Spain, Canary Islands, Hekker 

s.n. (L 0447515). 

Mercurialis jordani Sennen: Spain, Sennen s.n. (L 

0157687). Name only in herbarium, not in http:// 

www.ipni.org. 

Mercurialis leiocarpa Siebold & Zucc.: Taiwan, S. 

Saito 7692 (L 0447270). 

Mercurialis ovata Sternb. & Hoppe: Hungary, 

Unknown s.n. (L 0157702). 

Micrococca lancifolia Prain: Madagascar, d’Alleizette 

s.n., x.1906 (L 0158008). 

Micrococca malaccensis Airy Shaw: Malaysia, Johore, 

M. Shah & Ahmad 2437 (L 0158009). 

Micrococca mercurialis (L.) Benth.: Malaysia, Trengganu, 

SF (Sinclair & Kiah ) 39822 (L 0158021); 

Tanzania, Stolz 1207 (L 0158014). 

Micrococca oligandra (Müll.Arg.) Prain: India, Kostermans 

26309 (L 0158022). 

Micrococca wightii (Hook.f.) Prain: India, Ridsdale 

669 (L 0158025).

Styloid crystals in Claoxylon (Euphorbiaceae) - Red de Bibliotecas

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