Botanical Journal of the Linnean Society (1987), 94: 111-126. With 8 figures Wood anatomy of the Euphorbiaceae, 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 Glochidion 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. Antidesmeae (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. Phyllantheae 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 plants an unusual habit, like the candelabra Euphorbias or the ericoid Clutia. 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, Acalypha, 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 species 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 Astrocasia excepted B. Flueggeinae DiscocarpusDiscocarpus excepted Actephila included 2. Amanoeae Actephila excepted Place of tribe Poranthereae dubious. Position of the genera Antidesma, Astrocasia, Didymocistus, Discocarpus,Jablonskia, and Uapaca (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 genus 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 Lachnostylis PentabrachiumPenlabrachium Wielandia Bridelieae Cleistanthus DicoelieaeDicoclicae Poranthereae Spondiantheae Spondianthus Antidesmeae Hyeronima Thecacoris and Astrocasia Savia Blotia Amanoeae Amanoa AclephilaActephila Bridelia Cleistanthus Dicoelia Andrachne 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