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Home , Amanoa, Antidesmeae, Bridelia, Chascotheca, Cleistanthus, Clutia

Botanical Journal of the Linnean Society (1987), 94: 111-126. With 8 figures

Wood anatomy of the , in particular of the subfamily Phyllanthoideae

Alberta+M.W. Mennega

Institute of Systematic Botany, Rijksuniversiteit, Utrecht, The Netherlands

Received June 1986, accepted for Publication September 1986

M. 1987. Wood of the in MENNEGA, ALBERTA, W., anatomy Euphorbiaceae, particular

of the The in of subfamily Phyllanthoideae. great variety wood structure the large family

Euphorbiaceae makes it impossible to describe briefly a generalwood pattern. Nevertheless, a more

or less clear division into four anatomical groups can be made.

A short overview is given of the wood structure of the uni-ovulate subfamilies Acalyphoideae,

Crotonoideae, and Euphorbioideae, following the classification by Webster. These subfamilies

be their cannot distinguished by anatomy. The paper is mainly devoted to the bi-ovulate subfamily

Within this two be on the basis of their wood Phyllanthoideae. subfamily, groups can recognized the anatomy: Aporusa type with a great number of primitive characters, and the type, in

which features such scalariform vessel short primitive as perforation plates are absent. A description

of the 13 tribes is well for of the succession of the tribes. In given as as suggestions rearrangement

tribes several some taxa are anomalous and, on anatomical evidence, exclusion of some genera,

sometimes with assignment to another tribe, is suggested.

Fibre Additional key words: types parenchyma Stilaginaceae Uapacaceae

Contents

Introduction 112

Material 112

Characters used for establishing an evolutionary grouping of the

tribes in the subfamily Phyllanthoideae 112

Short descriptions of the tribes of Phyllanthoideae 116

Tribe 8. Aporuseae (Lindl. ex Miq.) Airy Shaw 116

Tribe 7. (Endl.) Hurusawa 116

Tribe 9. Drypeteae (Griseb.) Hurusawa 117

Tribe 1. Wielandieae Baill. ex Hurusawa 118

Tribe 2. Amanoeae (Pax & Hoffm.) Webster 119

Tribe 6. Spondianthea Webster 119

Tribe 3. Bridelieae Muell. Arg 121

Tribe 11. Hymenocardieae (Muell. Arg.) Hutch 121

Tribe 13. Bischofieae (Muell. Arg.) Hurusawa 122

Tribe 4. Dicoelieae Hurusawa 122

Table 5. Poranthereae (Muell. Arg.) Griming 122

Tribe 10. Dumort. 122

Tribe 12. Uapaceae (Muell. Arg.) Hutch 124

Conclusions 124

Acknowledgements 125

References 125

111

0024—4074/87/020111+ 16 503.00/0 (g) 1987 The Linnean Society of London 112 A. M. W. MENNEGA

Introduction

The large family Euphorbiaceae includes a great number of woody taxa,

with shrubs, trees, a few lianas, and some an unusual habit, like the candelabra or the ericoid . The wood structure also shows a great variation. It is impossible to present a general diagnosis of an euphorbiaceous wood. However, at least three, perhaps four types of wood can be distinguished. Metcalfe & Chalk (1950), in the Anatomy of the Dicotyledons, recognized three types in the subfamily Phyllanthoideae; the Aporusa type, the in Glochidion type, and a group of taxa designated “other genera”; the subfamily

Crotonoideae the structure is far more uniform, but different from the structure in In taxonomic have been Phyllanthoideae. recent years new treatments published, including those of Hutchinson (1969) and Webster (1975). The latter

because classification of system is followed in the present paper, the proposed better with the wood anatomical data than that of Hutchinson. genera agrees Webster recognizes five subfamilies: Phyllanthoideae and Oldfieldioideae

the (comprising all the bi-ovulate genera), while uni-ovulate genera are placed in Acalyphoideae, Crotonoideae and Euphorbioideae. With some exceptions

the (among others, , Clutia, Pogonophora) basic pattern of the wood is alike in the the three last-mentioned subfamilies. It is genera belonging to characterized absence of scalariform vessel of by perforation plates; presence medium intervascular and similar to very large pitting, vessel/ray pitting;

of diffuse banded presence apotracheal or parenchyma; numerous narrow, heterocellular often and often wide and thin- rays, vertically fused; non-septate, walled fibres.

The subfamily Oldfieldioideae, comprising most of the “other genera” mentioned is treated in the because this has been above, not present paper studied extensively by Hayden (1980).

In this paper short descriptions are given of the tribes of the Phyllanthoideae composed as in Webster’s Conspectus, but arranged in a differentorder, entirely based on the results of wood anatomy. The results are summarized in Table 1. tribes did sometimes In most one or more genera not seem well placed; a suggestion has been made for a better positioning, but sometimes this was not possible.

MATERIAL

of the The part of this paper dealing with the anatomy subfamily 141 Phyllanthoideae is based on examination of slides and macerations of

The information the subfamilies specimens of 116 and 35 genera. on

data Acalyphoideae, Crotonoideae and Euphorbioideae is founded on from,

39 and 17 respectively, 45, genera.

in the Wood of The slides are housed Anatomy Section of the Institute

of Utrecht. Full details be obtained Systematic Botany, University may on application to the author.

CHARACTERS USED FOR ESTABLISHING AN EVOLUTIONARY GROUPING OF THE TRIBES

IN THE SUBFAMILY PHYLLANTHOIDEAE

of the tribes in the and shown in Table The sequence descriptive section, as 1, is based wood characters that be considered definite entirely on may as having a WOOD ANATOMY OF THE EUPHORBIACEAE 113

Table 1. Subfamily Phyllanthoideae Aschers. A

suggested rearrangement of Webster’s tribes

based on wood anatomical data

Aporusa type Glochidion type

8. AporuseaeAporuseac 6.6. Spondiantheae Didymocistus excepted 3. Bridelieae MartreliaMartretia included 11. Hymenocardieae

7. Antidesmeae 13. Bischofieae

Antidesma excepted 4. Dicoelieae

9. Drypeteae 5. Poranthereae Paradrypetes included 10. Phyllantheae 1.1, Wielandieae A. Securineginae excepted B. Flueggeinae DiscocarpusDiscocarpus excepted Actephila included

2. Amanoeae

Actephila excepted

Place of tribe Poranthereae dubious.

Position of the genera , Astrocasia, Didymocistus,

Discocarpus,, and (tribe 12. Uapaceae) undecided.

relation to phylogeny. Particularly in the case of the Phyllanthoideae, these features are evident in the vessels, the fibres and the parenchyma. In Table 2 characters the important of the vessels of all genera investigated are summarized. The most primitive type of wood shows vessels with scalariform perforation plates, long vessel elements, medium to large intervascular pitting and similar vessel/ray pitting; long, thick-walled, non-septate fibres with bordered pits on the tangential as well as the radial walls, and parenchyma in

in the theoretical diffuse strands, or short irregular bands one cell wide. (For underlying principles the reader is referred to Chalk, 1983.) Slightly more advanced considered be those in genera are to which some of the vessel

scalariform and others in combination with perforation plates are simple, very fine intervascular The with pitting. next group comprises taxa simple perforation plates and medium to large intervascular pits, with and without parenchyma; the fibres are septate or not. The combination of characters considered advanced includes most vessels with simple perforation plates,

medium-sized vessel elements, small intervascular and vessel/ray pitting, absence of parenchyma or some paratracheal parenchyma, and septate fibres. It is worth that often in tribes where of the show diffuse noting most genera or short bands of and fibres of parenchyma non-septate one seems out place the absence of and of fibres. by parenchyma presence septate

Several of the genera with the Aporusa type of wood structure have a special

type of fibre wall thickening, first described by Bamber (1974). He noted two in the types subfamily Phyllanthoideae sensu Pax: type I with normal thickening of II with thick walls the walls, type very completely occluding the lumen, and

abnormal In all fibres of in this showing birefringence. some genera are type II, referred Bamber in both in paper to as type II; others, types occur, as Actephila II also in (see Fig. 4). Apart from the Phyllanthoideae, Bamber type occurs some genera of the Oldfieldioideae, but not in the other three subfamilies, with

the possible exception of Pogonophora (Giraud, 1983). 114 A. M. W. MENNEGA

pmurn 1200 12001200 1350 1300 14701470 1000 1090 920 1250 875 800>800 >

length pmJim Average 450 800 750 700 700 550 700 660 element 350-800

pm

350350 350

<

medium to Phyllanthoideae vessel/ray medium largelarge + + + + + + pitting pitting Intervascular vessel/ray subfamily pm Intervascular 4 Intervascular 4

and c. of ++ + + + + + + + + + + + + SimilarSimilar characters

vessel Exclusively simplesimple + + + + + + + + + + +4-

plates

Selected PartlyPartly + + +

2. Perforation Table Scalariform Exclusively + + + +-I- +

1975)

s WebsterWebster’s sequencesequence (Webster, coris to Wielandieae DiscocarpusDiscocarpus Heywoodia PentabrachiumPenlabrachium Wielandia Bridelieae DicoelieaeDicoclicae Poranthereae Spondiantheae Antidesmeae Hyeronima and Astrocasia Blotia Amanoeae AclephilaActephila Cleistanthus Dicoelia Antidesma Celianella Hyeronima Theca ing ectus 1. ribes according Conspectus i. 2. 3 4. 5. 6. 7. Tribes accord Conspi 2. 3 4. 5. 6. 7. T WOOD ANATOMY OF THE EUPHORBIAGEAE 115

1550 1500 1450 12001200 1860 1640 1035 900900 1700 865 865 1040 940 850

560560 630 600 630630 525 770 740 750750 800 550 750 1200

+4- + + + +4- +4- +4- + +4- +4- +4- + +4- 4-+ + +4- +

+4- + +4- +4- +4- +4- +4-

1984). Brandt,

+ +4- +4- 4--1- +4- 4-+ +4- + + +4- +4- +4- + subfamily. & Hayden the

in pitting. +4- + +4- + 4-+ + +4- (see position Flucggeinae vessel/ray

+4- +4- + +4- + + uncertain 10B large

an and of subtribe pitting genera in t well f * sedis, gabaria fits Securineginae ChascothecaChascolheca SecurinegaSecurinega Flucggeinae Glochidion MargaritriaMargarilaria PhyllantusPhyllanthus RicheriellaRicheriella'f intervascular Aporuseae Aporusa Didymocistus MaesobotryaProtomegabariaProtome AshtoniaAshlonia Drypeteae Putranjiva Neowawrea Phyllantheae HymenocardieaeHymenocardieac Uapaceae Uapaca Bischofieae BischofiaBischqfia Jablonskia Paradrypetes incertae A B 11. = Neowawrea fSmall i.s. * 8. 9. 10. 11. 12. 13. i.s. i.s. i.s. 116 A. M. W. MENNEGA

Another feature of the fibres in Euphorbiaceae in general is the frequent

but has occurrence of gelatinous walls, this character no relation to phylogeny.

Characters of the have been used in order rays not establishing a phylogenetic

all rather and because they are similar, of a primitive type.

SHORT DESCRIPTIONS OF THE TRIBES OF PHYLLANTHOIDEAE

The first five tribes be described all the of to belong to group A, Aporusa type & Chalk This is Metcalfe (1950). type mainly characterized by scalariform perforation plates in all or at least part of the vessels, long vessel elements,

of in diffuse strands in presence parenchyma or short, narrow, irregular bands, non-septate, long and thick-walled fibres, and wide, high, heterogeneous rays (Figs 1-3).

Tribe 8. Aporuseae (Lindl. ex Miq.) Airy Shaw

The tribe 7 all wood comprises genera, represented by samples (Figs 1-3).

vessels with partly scalariform, partly simple perforation plates; vessel elements 1-2 intervascular the very long, mm; pitting medium-sized, vessel/ray pitting similar or larger, parenchyma in diffuse strands or in short, scattered bands one cell wide; strands of 8-14 cells, rays uniseriate and multiseriate,

(2-)6(-9) cells wide, the multiseriate part composed of many rows of total 2 sheath procumbent cells, the extensions usually very high; height 8 mm; cells often Bamber in present, fibres very thick-walled, type II, except

Protomegabaria and Didymocistus, non-septate, large bordered pits on radial and

tangential walls; mean length 2900 pm.

The wood of the is with the of structure genera remarkably similar, exception

In this is fibres are thin- Didymocistus. monotypic genus parenchyma absent, walled, wide, and partly septate, scalariform vessel perforation plates are rare.

Tribe 7. Antidesmeae (Endl.) Hurusawa

The tribe consists of 5 wood available for Antidesma and genera; samples were Hyeronima, but only pieces of twigs of Celianella and Thecacoris.

vessel perforation plates, partly scalariform, partly simple, but in Antidesma exclusively simple, element length on average 900 pm; intervascular pitting

in 5-7 pm; the vessel/ray pitting moderately large to large, oval, often elongate, scalariform arrangement, parenchyma as isolated strands, or in short, diffuse In and absent bands one cell wide; Antidesma exclusively scarce paratracheal, in

Celianella. uniseriate and 2-4 cells the middle rays multiseriate, wide, part very often of mixed and the extensions of high, composed procumbent square cells, tall cells fused erect moderately to very high, vertically rays frequent; height up to 5 mm. fibres in and Thecacoris in non-septate Hyeronima , partly septate Antidesma and Celianella with bordered in thin- ; thick-walled, pits Hyeronima ; walled and often in Antidesma and Celianella radial gelatinous ; simple pits on

1760 walls; mean length pm.

tribe is in its Celianella shows the This not homogeneous structure. same type of structure as Didymocistus regarding the absence of parenchyma and the

thin-walled fibres of moderate Antidesma shares occasional septate length. the WOOD ANATOMY OF THE EUPHORBIACEAE 117

1. with medium- Figures 1-4. Fig. Aporusa microcalyx tangential section showing a wide ray, a vessel Cross-section of sized intervascular pitting, part of a parenchyma strand with large pits. Fig. 2. A. microcalyx showing vessel grouping and fine irregular bands ofparenchyma. Fig. 3. Radial section of A. microcalyx showing the large vessel/ray pitting. Fig. 4. Actephila excelsa showing normal thick-

fibres with occluded Bamber’s II. Scale bars = 100 walled fibres, and three lumen, type µm.

fibres with the but it also lacks scalariform thin-walled, septate foregoing genera, Metcalfe Chalk Antidesma in B perforation plates. In & (1950), was placed group with Glochidion-type of wood, associated with Hymenocardia and Aporosella. The wood shows affinities with Spondianthus (tribe 6, Spondiantheae) but also with

Antidesma is of the of doubtful Bischofia (tribe 13, Bischofieae). one genera

taxonomic position: Airy Shaw (1965) transferred it to the family Stilaginaceae,

in the suggesting affinities with Icacinaceae. Such an affinity is not expressed wood anatomy. To me the wood structure fits well with Phyllanthoideae, but it should be in perhaps placed a tribe by itself.

Tribe 9. Drypeteae (Griseb.) Hurusawa

In Webster’s classification the tribe comprises Drypetes, Neowawrea, and

No wood of Neowawrea available to but from the extensive Putranjiva. was me, 118 A. M. W. MENNEGA

& Brandt of the I convinced that treatment by Hayden (1984) genus, am it was

this tribe. I with their conclusion that it should be wrongly assigned to agree placed in subtribe 10B, Flueggeinae.

vessel perforation plates partly simple, partly scalariform. Vessel element

length (770-)900(-2000) pm; intervascular pitting minute, 3-4 pm, the ray/vessel pitting similar, parenchyma apotracheal in numerous short, often interrupted bands one cell wide; strands of 6 14 cells, rays uniseriate and multiseriate, 2 3 cells often uniseriate wide, the wide part very high, and the extensions also high; fused from vertically rays frequent; height 1.5 to 4 mm. fibres non-septate, very

Bamber small radial 1575-3000 thick-walled, type II; pits on walls, length pm.

Drypetes and Putranjiva are anatomically similar. Some species ofDrypetes show a marked resemblance to species of Wielandia and Heywoodia. The wood structure of Paradrypetes Kuhlm. is, according to descriptions by Milanez (1935) and by

Matos & Mattos Filho that Araujo (1984), almost identical to ofDrypetes, except for the large oval, scalariformly arranged vessel/ray pits in Paradrypetes. This combination of very small intervascular pits and large scalariform vessel/ray

in in pitting is unusual Euphorbiaceae, but it is also present Richeriella (tribe 10B, Phyllantheae).

Tribe 1. Wielandieae Baill. ex Hurusawa

This tribe 11 wood available of the comprises genera, specimens were genera mentioned below. Vessel perforation plates partly or exclusively scalariform in Blotia, Heywoodia, Pentabrachium and Wielandia, exclusively simple in Astrocasia,

and Savia. Vessel elements , Lachnostylis over 1000 pm long in the with scalariform genera perforation plates (except Heywoodia), 800 pm or less in

the other genera.

Vessels often in radial intervascular numerous, narrow, arranged long rows,

and small in all parenchyma diffuse in pitting vessel/ray pitting genera, or short distributed bands one cell but and restricted irregularly wide, very scarce to some paratracheal strands in Discocarpus and completely absent in Astrocasia. rays more or less alike in all for the wide and in genera, except very high rays

Blotia 120 = 11 cells wide and the middle (up to pm up to 8 mm high), part of the 2-3 cells the extensions rays wide, usually very high, extremely high to fused from 600 3000 moderately high; vertically rays frequent; height to pm.

thick-walled in fibres non-septate, very with a minute lumen (Bamber type II) Blotia, Heywoodia, Lachnostylis, Savia and Wielandia. In Astrocasia, Discocarpus and

Pentabrachium, fibres sometimes septate with thin walls; walls sometimes

gelatinous; length 1300-2400pm, shorter in Astrocasia (740 pm).

The taxa of this tribe show variation in structure. Blotia has the most primitive wood structure of all Euphorbiaceae as seen by the numerous bars of

the scalariform perforation plates in combination with long vessel elements, long fibres with thick wide and and diffuse walls, high rays, parenchyma. Others, Savia also show but combined with such as and Lachnostylis, primitive features, more advanced characters, whereas Discocarpus, and in particular Astrocasia,

seem out of place in this tribe. Punt the of of its According to (1962) pollen Discocarpus represents a type own intermediate between that of Amanoa and that of Antidesma. Anatomically

with Discocarpus shows more affinities Antidesma than with Amonoa. Punt WOOD ANATOMY OF THE EUPHORBIACEAE 119 commented furthermore that the pollen grains of Astrocasia are undoubtedly of

the - type (a type that should now be called the Flueggea type, see Webster, 1984a). The wood structure shows affinities with Breynia of the subtribe

Phyllanthoideae, but also with Andrachne of tribe Porantheroideae.

The wood structure of Pentabrachium closely resembles that of Actephila of the

tribe Amanoeae.

Tribe 2. Amanoeae (Pax & Hoffm.) Webster

Amanoa and the of Actephila are only two genera Amanoeae.

vessels with scalariform perforation plates in Actephila, simple in Amanoa;

element intervascular small length (1030-) 1400(-1570) pm; pitting very to the similar, in minute, vessel/ray pitting parenchyma diffuse, short bands one cell wide in Amanoa, absent or restricted to a few paratracheal cells in Actephila.

rays uniseriate and multiseriate, mostly uniseriate in Amanoa, the multiseriates

2-4 cells fused the of cells different in the wide; vertically rays present; type ray

cells in in latter two genera, erect scarce Amanoa, abundant in Actephila, the sheath cells also genus present, as well as perforated ray cells with scalariform

and in perforations, fibres not septate very thick-walled, Bamber type II, and sometimes with thick Bamber Amanoa, septate very walls, type II, sometimes

with moderately thick walls and a distinct lumen in Actephila (Fig. 4), the length

in both genera about 2100 pm.

The structure of the wood of the is different from the two genera so markedly

that anatomical point of view there is no evidence to support their retention in the tribe. Amanoa has same several features in common with Savia, whereas

Actephila seems closely related to Pentabrachium as mentioned before. However, it

35 of should be noted that of the species Actephila, wood samples were available only of A. excelsa var . javanica.

The 8 tribes the Glochidion- of Metcalfe & remaining belong to group B, type

Chalk (1950). This type is chiefly characterized by simple vessel perforation

plates, absence of parenchyma (sometimes a few paratracheal strands), thin-

walled septate fibres (Figs 5-8).

Tribe 6. Spondiantheae Webster

is the of this tribe. Spondianthus only genus

vessel perforation plates simple, though one vessel with scalariform

element 1090 intravascular perforation noted; length on average pm, pitting

large, c. 12 pm; vessel/ray pitting large and oval, or + circular, parenchyma

mostly paratracheal, scarce, as incomplete or slightly aliform rings, occasionally diffuse strands, uniseriate and 5-8 cells wide and some rays multiseriate, very

3-4 the middle and of and high, up to mm, part high composed procumbent the extensions sometimes walls square cells, not very high, fibres septate, thick and lumen 2660 moderately wide, average length pm.

In Metcalfe & Chalk (1950), Spondianthus is considered as a rather problematic the I if it is genus doubtfully belonging to Euphorbiaceae. quote: . . correctly in the falls into this placed Euphorbiaceae, [it] group [Glochidion- type] on

account of its fibres. It has the of the septate large rays typical group A,

intervascular pitting is similar to that of Antidesma, and the occurrence of 120 A. M. W. MENNEGA

Figures 5-8. Fig. 5. Glochidion borneense cross section, parenchyma absent. Fig. 6. Tangential section

thin-walled fibres, multiseriate 2-3 cells wide. 7. Radial of G. obscurum showing septate rays Fig. of fibres. 8. Cross- section of the same species with large elongate crystals in some the septate Fig. of section resemblance to Glochidion; vessels with thin tyloses. Scale Bischofia javanica , showing

bars = 100 µm.

vasicentric parenchyma suggest Bridelia; only the pitting between vessels and

be and circular”. had the rays cannot matched, being large usually Having

material of A and I do consider the opportunity to see more groups B, not

vessel/ray pitting of Spondianthus so different from that of Antidesma or .

On of the the vessel elements and this tribe account large rays, long long fibres, transitional between A and B. seems to occupy a position groups WOOD ANATOMY OF THE EUPHORBIACEAE 121

Tribe 3. Bridelieae Muell. Arg.

The tribe the Bridelia comprises genera and Cleistanthus.

vessel element perforation plates exclusively simple, mean length 550 pm in Bridelia, 1000 in Cleislanlhus intervascular pm ; pits 5-10 pm wide, vestured in

Bridelia, 2-3 pm wide in Cleistanthus, the vessel/ray pitting in Bridelia large, rounded Cleistanthus to oval, in similar to the small intervascular pits, but and scalariform. occasionally unilaterally compound parenchyma scarce,

strands of paratracheal, 2-8 cells, rays uniseriate and multiseriate, 2-6 cells the wide, middle part heterocellular with scarce truly procumbent cells, the extensions of and fused square erect cells, high; vertically rays often present; 3.5 1.5 height up to mm, usually c. mm. fibres septate, thin- to thick-walled, often with gelatinous walls, pits small with a narrow border, restricted to the radial walls; mean length 1240 pm for Bridelia, 1800 pm for Cleistanthus.

Since in all and taxonomic classifications Bridelia Cleistanthus are placed together, the anatomical differences in pitting and length of vessel elements and fibres are apparently more of diagnostic importance than an indication that the unrelated. genera are

Tribe 11. Hymenocardieae (Muell. Arg.) Hutch.

is the in this tribe. Hymenocardia only genus

vessel element 550 perforation plates simple; length on average pm; intervascular 5-7 pitting pm wide, the vessel/ray pits partly + circular, partly often in large, elongate, scalariform arrangement, parenchyma absent, rays

uniseriate and 2-3 cells with middle multiseriate, wide, a very high portion and

fused often 3 equally high extensions; vertically rays present, height up to mm. walls fibres septate, moderately thick, length on average 1300 pm.

Hymenocardia is a taxon of controversial position within the Euphorbiaceae. Shaw considered the Airy (1965) genus as not belonging to the family, because of its fruit and He the in winged pollen structure. placed genus a separate family

Hymenocardiaceae, and suggested a relationship with , also drawing

attention to a resemblance with Holoptelea of Ulmaceae. Other authors in their of African treatments floras followed his idea of a new family, for example

Radcliffe-Smith (1973) and recently Leonard & Mosango (1985); (see also

in papers this volume by Radcliffe-Smith and Webster). From the wood anatomical of view in the point a position Euphorbiaceae is not entirely

unreasonable, a certain resemblance to Spondianthus exists. Metcalfe & Chalk

(1950) placed Hymenocardia somewhere near to Glochidion and Aporosella (now

included in Phyllanthus), but at the same time an alliance with three tribes of the

Flacourtiaceae was mentioned. From data and from those of my own

Robbrecht in Dechamps, Mosango & (1985), which are close agreement, a

similarity to some genera of the tribe Casearieae (according to the treatment of Miller is but (1975)) present, discrepancies also exist. This similarity is not only

for but with true Hymenocardia, for several more genera the Glochidion type of wood structure. A relationship with Urticaceae is anatomically not acceptable,

and the wood of Holoptelea with its storied structure is entirely different. 122 A. M. W. MENNEGA

Tribe 13. Bischofieae (Muell. Arg.) Hurusawa

A monotypic tribe, comprising Bischofia (Fig. 8). elements 1040 vessel perforation plates simple; on average pm long; intervascular pitting large, 12 pm; ray/vessel pitting + circular and large elliptic or irregular, parenchyma absent, rays uniseriate and multiseriate, cells wide, the middle part high, extension low to high, sheath cells often present, up to wide and few 2 mm high, fibres septate, very (40 pm) thin-walled, pits on radial walls; length 2175 pm.

is in Shaw This another genus of disputed placement the Euphorbiaceae. Airy established the Bischofiaceae accommodate the and (1965) family to genus, suggested affinities with Staphyleaceae, a suggestion not endorsed by wood

Neither does the wood with that of of the anatomy. structure agree genera subtribe Paiveusinae (subfamily Oldfieldioideae) as was pointed out by Hayden

In fits well in the Glochidion of the (1980). my opinion Bischofia type either in tribe of its in the subtribe Phyllanthoideae, a own, or even Flueggeinae of the Phyllantheae.

Tribe 4. Dicoelieae Hurusawa

A monotypic tribe, comprising Dicoelia.

vessels with simple perforation plates, though in thin twigs some scalariform Intervascular perforations present. Vessel element length on average 700 pm. 3—4 similar, almost pitting very small, pm, vessel/ray pits parenchyma absent, a

few strands occasionally adjacent to vessels, rays uniseriate and 2-5-seriate, the

latter with middle and 2 a high part very high extensions, height up to mm; rays and often vertically fused, fibres septate non-septate; moderately thick-walled,

minute bordered pits on radial walls; length c. 1210 pm.

this is isolated with obscure affinities. According to Airy Shaw, a very genus

The wood structure shows resemblance to Cleistanthus.

Tribe 5. Poranthereae (Muell. Arg.) Grüning

The three in this tribe subshrubs herbs. The material genera are or only

available was the woody base of a specimen of Andrachne aspera.

vessel perforation plates simple; element length short, 350 pm; intervascular similar pits very fine, the vessel/ray pitting or slightly wider, unilaterally

difficult uniseriate and compound, parenchyma scarce, diffuse, to see. rays cells and with small biseriate, most square erect, fibres non-septate, numerous bordered radial and 580 pits on tangential walls; length pm on average.

The short vessel elements and fibres are probably related to the habit of the specimen. This habit makes interpretation of the data difficult. The absence of

septate fibres makes a place amongst the tribes with Aporusa type of wood seem

appropriate. The place I have given it seems doubtful.

Tribe 10. Phyllantheae Dumort.

This tribe is split into two subtribes: Securineginae and Flueggeinae. WOOD ANATOMY OF THE EUPHORBIACEAE 123

Subtribe 10A. Securineginae Muell. Arg.

This subtribe comprises nine genera; wood samples of Securinega, and Pseudolachnostylis were available.

vessel perforation plates simple in Securinega and Pseudolachnostylis, exclusively scalariform with 8-15 bars in mean element 600 Chascotheca; length c. pm intervascular 2.5-4.0-6.0 pitting very small, pm, the vessel/ray pitting similar. parenchyma abundant in bands 2—6 cells wide in Pseudolachnostylis, diffuse and in in irregular bands one cell wide Securinega, and absent in Chascolheca; strands of cells, and 8-12 rays uniseriate 2-3 cells wide, up to 5 cells wide in

extension in Chascotheca the extensions Pseudolachnostylis; low; very high in

fused in Securinega moderately high; vertically rays frequent except

Pseudolachnostylis. fibres non-septate, thick-walled with small bordered pits on the radial and tangential walls in Securinega and Pseudotachnostylis; thin-walled, often with and fibres gelatinous walls, some septate, pits small, simple on the radial walls in Chascotheca. only Length on average 900 pm.

in Chascotheca shows, like Didymocistus Wielandieae, the same complex of characters differing from those of other members of the subtribe; scalariform

absence of and perforation plates, parenchyma, partly septate fibres. Securinega and do Pseudolachnostylis not comply with the general aspect of the Glochidion type of wood structure by their variable amounts of parenchyma and the absence of septate fibres, features characteristic for the Aporusa type. In fact, Metcalfe & Chalk cited the wood of (1950) Lingelsheimia, another genus of this subtribe (not

in investigated here), as resembling Drypetes group A, which also applies for the two genera Securinega and Pseudolachnostylis.

Subtribe 10 B. Flueggeinae Muell. Arg.

A large taxon comprising Breynia, Flueggea, Glochidion (Figs 5-7), , and Phyllanthus, Richeriella, Sauropus two more genera of which no wood was available. Neowawrea, incorporated in Drypeteae, should be included in this subtribe, as already mentioned.

vessel perforation plates exclusively simple; mean vessel element length

720 intervascular in pm; pits medium-sized, 5-8 pm, except Breynia and Sauropus where the + circular pits very small; vessel/ray pitting large, or, often, narrow, in horizontal with the oval, arranged rows, again exception of Breynia and with similar the intervascular Sauropus pitting to pits, parenchyma absent, or very scarce to scanty, paratracheal as a few strands adjacent to a vessel, strands of 2-8-10 cells, rays uniseriate and multiseriate, 2-3 cells wide (much wider in

the middle not of and Phyllanthus emblica), part very high, composed square

short cells, extensions to fused relatively procumbent very high high; vertically often total from rays present; height 1.5 to 4.5 mm, higher in Phyllanthus emblica. fibres walls but often septate, generally thin, gelatinous, small pits restricted to the radial 1340 walls; length on average pm.

The wood structure of the subtribe is for the remarkably uniform, except very small in and These pits Breynia Sauropus. two genera show a great similarity, which is in accordance with the remark ofAiry Shaw (1975) in his treatment of the Euphorbiaceae of , that Breynia, Sauropus and Synostemon are scarcely distinct Metcalfe & Chalk treat in the of genera. (1950) Breynia group “other 124 A. M. W. MENNEGA

genera”, but their description is entirely different from the wood structure of the three of various the is specimens species seen by me; discrepancy most probably due to incorrectly identified material.

Until recently much confusion existed between wood samples assigned either to Securinega or Flueggea. From the foregoing descriptions it will be evident that these taxa are far more different in their wood structure than of the any genera of the subtribe Flueggeinae are among themselves. Webster (1984a), in his revision of Flueggea, has straightened out this confusing state. Securinega is now restricted to four species, three from Madagascar and one from Mauritius, all

the of wood showing same type structure.

Tribe 12. Uapaceae (Muell. Arg.) Hutch.

A tribe of doubtful monotypic position, considered by Airy Shaw (1965) as

in belonging a separate family having affinities with Anacardiaceae and Picrodendraceae.

vessels with simple perforation plates, though Normand (1955) mentioned an occasional scalariform perforation; element length c. 750 pm; intervascular pits

10 and pm, vessel/ray pitting large elliptic smaller roundish, parenchyma paratracheal as incomplete rings, also in short bands and diffuse; strands of 4-6 cells, rays uniseriate and multiseriate, 3-6 cells the middle wide, part very high and the extensions also often heterocellular, very high; rays vertically fused; height 3.5-5 mm. fibres thick-walled, non-septate, simple pits restricted to the radial 1900 walls; mean length pm.

The wood structure is in several respects unusual for the Euphorbiaceae. Metcalfe Chalk with the “other which & (1950) place Uapaca group genera”, comprises mainly the Oldfieldioideae. From a comparison of the wood structure of with the data for the in the Uapaca published by Hayden (1980) genera

Oldfieldioideae close affinities the subfamily no between taxa are apparent.

Giraud (1983) lists in her thesis a number of genera according to an

In evolutionary scala. this list Uapaca is placed next to Drypetes and near to

The three have indeed features in but I would . genera some common, hesitate to assign Uapaca to either Drypeteae or Antidesmeae.

CONCLUSIONS

Conclusions concerning the composition of the tribes have already been given, and the results summarized in Table 1. It is that the of are apparent sequence the tribes in Webster’s classification, as indicated by the numbers of the tribes, is quite different from the sequence obtained when anatomical characters are used classification. exclusively for The author is well aware that the data of wood anatomy have to be interpreted together with data from other disciplines, but she considers it helpful to present the anatomical information as a tool for a definitive classification. Results in the such the of marked past, as settling

differences noticed of anatomical among species Flueggea and Securinega by

Webster’s revision of Flueggea (Webster, 1984a), which brought uniformity to described either the specimens previously as belonging to one genus or other,

the strengthen wood anatomist in the believe that wood structure can offer a positive contribution to classification. WOOD ANATOMY OF THE EUPHORBIACEAE 125

The sequence of the tribes with woods of the Aporusa type has a sounder base

than the sequence in the other group. This is mainly due to the fact that in the anatomical well-established Aporusa type, characters, as indicating a primitive or more advanced state, are present, whereas such characters are less obvious in the of wood. the tribes much taxa with the Glochidion type Furthermore, or taxa are more alike, and distinctions are not clear.

The position of Poranthereae is dubious, partly because material was not adequate, but also because the wood characters are intermediate between the

Aporusa and Glochidion groups. This is also the case for the genera Antidesma,

Astrocasia, Didymocistus, Discocarpus and Jablonskia, genera in which some of the

fibres are septate and in which parenchyma is absent. The two last-mentioned also vessels with scalariform genera possess some perforation plates. in Tentatively Antidesma might be placed a tribe by itself amongst the tribes

in with Glochidion wood, or a family of its own as advocated by Airy Shaw

(1965) who re-established the family Stilaginaceae. Astrocasia might be related to

but lack of reliable material of the latter definite Andrachne, genus prevents a judgment. Jablonskia, a genus established by Webster (1984b), was provisionally placed by him somewhere near to Phyllantheae, subtribe Securineginae. In affinities with of the but it wood characters it shows more genera Aporusa group, fit of the tribes does not in any (Mennega, 1984).

is in several The wood of Uapaca respects different from that of the

Euphorbiaceae. Perhaps this taxon might better be assigned to a family

Uapacaceae in conformity with Airy Shaw’s suggestion (Airy Shaw, 1965).

the of Comments on taxonomic position Uapaca, as well as Hymenocardia and

and Webster Bischofia, will be found in the papers by Radcliffe-Smith by in this

volume.

Genera not listed by Webster (1975) are Martretia and Paradrypetes. Martretia

fits remarkably well in the tribe Aporuseae, a position corresponding to the

place next to Aporusa in Pax & Hoffman (1931).

resembles in is from Paradrypetes Drypetes very closely structure, as apparent

the description of Matos Araujo & Mattos Filho (1984), except for a different

type of vessel/ray pitting. Accordingly, I have included the genus in the tribe Drypeteae.

ACKNOWLEDGEMENTS

I Miss and Dr D. F. Cutler for am greatly indebted to Mary Gregory to reading and carefully correcting the preliminary manuscript, and for their helpful

comments.

REFERENCES

edition AIRY SHAW, H. K., 1965. Diagnoses of new families, new names etc., for the seventh of Willis’s ‘Dictionary’. Kew Bulletin, 18: 249-273.

AIRY SHAW, H. K., 1975. The Euphorbiaceae of Borneo. London: H.M.S.O.

BAMBER, R. K., 1974. Fibre types in wood ofEuphorbiaceae. Australian Journal of Botany, 22: 629-634.

CHALK, L., 1983. Wood anatomy, phylogeny, and . In C. R. Metcalfe & L. Chalk (Eds), Anatomy

of the Dicotyledons, 2nd edition, 2: 108-125. Oxford: Clarendon Press. DECHAMPS, R., MOSANGO, M. & ROBBRECHT, E., 1985. Etudes systematiques sur les Hymenocardiaceae d’Afrique: la morphologie du pollen et 1’anatomie du bois. Bulletin du Jardin Botanique

National de Belgique, 55: 473-485. 126 A. M. W. MENNEGA

arborescentes.’ GIRAUD, B., 1983. ‘Xylologie et Phylogenic des Euphorbiacees These de Doctoral d’Etat a

rUniversitc Pierre et Marie Curie, Paris.

HAYDEN, W. J., 1980. ‘Systematic Anatomy of Oldfieldioideae.’ Ph.D. Thesis, University of Maryland.

Wood of Neowawrea HAYDEN, W. J. & BRANDT, D. 1984. anatomy and relationships (Euphorbiaceae).

Systematic Botany, 9: 458-466. HUTCHINSON, J., 1969. Tribalism in the family Euphorbiaceae. American Journal of Botany, 56: 738-758.

LEONARD, J. & MOSANGO, M., 1985. Hymenocardiaceae. In Bamps, P. (Ed.) Flore d*Afrique Centrale: 1-16. Bruxelles: Jardin Botanique National de Belgique.

MATOS ARAUJO, P. A. & MATTOS FILHO, A. de., 1984. Estrutura das madeiras brasileiras de

Dicotiledoneas. XXVI. Euphorbiaceae. Rodriguesia, 36 (59): 25-40.

MENNEGA, A. M. W., 1984. Wood structure of Jablonskia congesta (Euphorbiaceae). Systematic Botany, 9:

236-239.

METCALFE, C. R. & CHALK, L., 1950. Anatomy of the Dicotyledons. Oxford: Clarendon Press.

MILANEZ, F. R., 1935. Anatomia de Paradrypetes ilicifolia. Arquivos do Institute de Biologia Vegetal. Rio de Janeiro,

133-156.

of MILLER, R. 1975. Systematic anatomy of the xylem and comments on the relationships Flacourtiaceae.

Journal of the Arnold Arboretum, 56: 20-102. NORMAND, D., 1955. Atlas des bois de la CSte d'lvoire, 2. Nogent-sur-Marne, France: Centre Technique

Forestier Tropical. PAX, F. & HOFFMAN, K., 1931. Euphorbiaceae. In A. Engler, Die natiirlichen Pfianzenfamilien, Band I9c: 11-233. Leipzig: W. Engelmann.

1962. Pollen of the with reference 7: PUNT, W., morphology Euphorbiaceae special to taxonomy. Wentia,

1-116.

RADCLIFFE-SMITH, A., 1973. A new variety of (Hymenocardiaceae) In F. N. Hepper (Ed.), Tropical African plants: XXXIII. Kew Bulletin, 28: 319-326.

WEBSTER, G. L., 1975. Conspectus of a new classification of the Euphorbiaceae. Taxon, 24: 593-601. WEBSTER, G. L., 1984 a. A revision of Flueggea (Euphorbiaceae). Allertonia, 3: 259-312. A of WEBSTER, G. L., 1984b. Jablonskia, new genus Euphorbiaceaefrom . Systematic Botany, 9:

229-235.