IAWA Journal, Vol. 16 (I), 1995: 87-95

WOOD ANATOMY OF FOUR MYRTACEAE GENERA IN THE SUBTRIBE MYRCIINAE FROM SOUTH AMERICA by

Claudia Luizon Dias-Lerne!, Peter Gasson2 & Eirnear Nie Lughadha2

SUMMARY

The wood anatomy of 31 species representing four genera of subtribe Myrciinae, Myrtaceae, Calyptranthes, Gomidesia, Marlierea and Myrcia is described. In general the wood of subtribe Myrciinae can be char­ acterised by solitary vessels, simple perforations, alternate vestured pits, fibres with bordered and/or vestured pits (fibre-tracheids), parenchyma scanty paratracheal, diffuse and/or diffuse-in-aggregates forming com­ plete or interrupted bands, and heterocellular rays with disjunctive cell walls. The four genera share all these features, but exhibit considerable variation in axial parenchyma patterns and crystal occurrence and distri­ bution. No anatomical features serve to separate the genera, but some, e. g., helical thickenings and crystals, appear to be restricted to species in one genus or another. All wood sampies were obtained from wood collections and the exact environmental conditions in which the trees grew are unknown. For this reason, it is impossible to assess the relative contributions of ecological and taxonomic factors to the observed anatomical variation. Key words: Myrtaceae, Calyptranthes, Gomidesia, Marlierea, Myrcia, South America.

INTRODUCTION

The Myrtaceae is a large family of trees and shrubs consisting of about 3850 species in 127 genera (Brummitt 1992, Mabberley 1987). The family is mainly tropical and subtropical worldwide and is well-represented in tropical South America. All but one of the South American species belong to the Myrteae, the baccate-fruited tribe. The most recent comprehensive revision of this tribe is that of Berg (1855/56), in which 3 subtribes are recognised within the Myrteae. The present study deals with the subtribe Myrciinae in which Berg distinguished 11 genera. Of these, only 5 (Calyptranthes, Gomidesia, Marlierea, Myrceugenia and Myrcia) are now recognised, the others being relegated to synonymy. Myrceugenia is very different from these Myrciinae and is postulated to be the primitive genus within the subtribe (Landrum 1981). This arrange­ ment was first suggested by McVaugh in his re-alignment of the American Myrteae (1968). He regarded the myrcioid genera as "perhaps the most readily compre-

1) Depto de Botänica, lust. Biociencias, Universidade de Silo Paulo, Silo Paulo, Brazil. 2) Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, United Kingdom.

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Table 1

Species Character (see key below): 2 3 4 5 6 7 8 9 10 11 12 13

Calyptranthes jasciculata Berg + + + + + >5 grandifolia Berg + + + + >8 lucida Mart. ex DC. + + + + + >8 pileata D. Legrand + + + + + + - 4-8 pulchella DC. + + + + + >8 speciosa Sagot + + + + + >8 widgreniana Berg + + + + >8 Gomidesia affinis (Cambess.) D. Legrand + + + - 5-8 anacardiifolia Berg + + + + + + + 4-8 sellowiana Berg + + + + + + - 4-8 tijucensis (Kiaersk.) D. Legrand + + + + + + + 4-8 Marlierea montana (AubI.) Amshoff + + + + + >8 parvijIora Berg + + + + + >8 scytophylla Diels + + + + + >8 spruceana Berg + + + + + + >5 sylvatica (Gardner) Kiaersk. + + + + + - 5-8 umbraticola (Kunth) Berg + + + + + + >8 Myrcia amazonica DC. + +/- +/- + + +/- - +/- - >8 bracteata (Rieh.) DC. + + + + + + 3-8 deflexa DC. + + +/- +/- + + - 3-8 jallaxDC. + + +/- +/- + + + +/- - 3-8 grandis McVaugh + + + + + + >5 guianensis DC. + + + + + >5 inaequiloba (DC.) D. Legrand + + + + + + >5 multijIora (Larn.) DC. + + + + + + - 3-8 pyrifolia (Desy. ex Harn.) Nied. + + + + + + + >5 servata MeVaugh + + + + - 3-8 splendens (Swartz) DC. + + + + + + - 3-8 subobliqua (Benth.) Nied. + + + + + >5 sylvatica (G. Meyer) DC. + + + + + >5 tomentosa (AubI.) DC. + + + + + - 4-10

1. Growth rings 8. Axial parenchyma in bands more than three 2. Fibres thick-walled cells wide 3. Fibres thin-walled 9. Axial parenehyma with erystals 4. Axial parenchyma diffuse 10. Dark contents 5. Axial parenchyma diffuse in aggregates 11. Pith flecks 6. Axial parenchyma scanty paratracheal 12. Helical wall thickenings in fibres 7. Axial parenchyma in bands up to three 13. Axial parenchyma strand length (number of cells wide cells)

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---~ hensible of the groups of Myrteae." He also highlighted the absence of sharp dis­ tinctions between the genera and suggested that if all historical considerations could be set aside, Calyptranthes, Marlierea and Myrcia might be combined in one vast genus. As currently recognised Gomidesia is distinct by virtue of its 4-locular anthers, the other 3 genera having bilocular, longitudinally dehiscent and explanate anthers. Both Gomidesia and Myrcia have more or less regularly 5-lobed calyces, while Mar­ lierea has an irregularly splitting 3- to 5-lobed calyx and Calyptranthes has a closed circumscissile calyx. However, both anther and calyx characters vary continuously and, as Mc Vaugh emphasised, there are many borderline species which have to be assigned arbitrarily to one genus or another. These problems of generic delimitation prompted the present study, which com­ prises a survey of the wood anatomy of 31 species representing the spectrum of diver­ sity of the myrcioid genera and a review of previously published wood anatomical data for this group. There are no detailed comparative works on the wood anatomy of these four genera, although they are all included in the general description of Myrtaceous wood by Metcalfe and Chalk (1950). Detienne et al. (1982) and Detienne and Jacquet (1983) include representatives of Calyptranthes, Marlierea and Myrcia. Ilic (1991) illustrates Calyptranthes and Myrcia and Schmid and Baas (1984) describe vessel characters of Myrcia. The only description of Gomidesia wood anatomy (Barbosa et al. 1977/78) appears to be based on a collection of Myrcia pubipetala Miq. errone­ ously identified as Gomidesia crocea (Vell.) Berg. We have examined 7 species of Calyptranthes, 4 of Gomidesia, 6 of Marlierea and 14 of Myrcia (Table 1) to provide the most detailed wood anatomical account of the genera to date.

MATERIAL AND METHODS

Wood samples and slides of the 31 species in 4 genera studied in this paper were ob­ tained from: Institute of Systematic Botany, University of Utrecht, The Netherlands (Uw); Museum Collections, Royal Botanic Gardens, Kew (Kw) and Rijksherbarium, Leiden, The Netherlands (all slides in Leiden were originally from the Oxford For­ estry Institute, FHOw). The abbreviations for wood collections follow those in Stern (1988).

Material studied: Calyptranthes Jasciculata Berg: Guyana, Uw 997 and FHOw 14782. - C. grandifolia Berg: Uw 6382. - C. lucida Mart. ex DC.: Suriname, Uw 2522. - C. pileata D. Le­ grand: Brazil, Uw 14519. - C. pulchella DC.: Brazil, Uw 19683. - C. speciosa Sagot: Suriname, Uw 340. - C. widgreniana Berg: Brazil, Uw 6383. - Gomidesia affinis (Carnbess.) D. Legrand var. catharinensis D. Legrand: Brazil, Uw 12946 and Uw l34l3. - G. anacardiifolia Berg: Brazil, Uw 6381, Uw 6903 and Kw 22082. - G. sellowiana Berg: Brazil, Uw 14028. - G. tijucensis (Kiaersk.) D. Legrand: Brazil, Uw 14341. - Marlierea montana (AubI.) Amshoff: Guyana, Uw 1003 and FHOw 14786. - M. parviflora Berg: Brazil, Uw 6923. - M. scytophylla Diels: Brazil, Uw 8069. - M. spruceana Berg: Brazil, Uw 7864. - M. sylvatica (Gardner) Kiaersk.: Brazil, Uw 12536. - M. umbraticola (Kunth) Berg: Brazil, Uw 7502 and Uw 7792. - Myrcia amazonica DC.: Suriname, Uw 2l3. - M. bracteata DC.: Surinam, Uw 1630. - M. deflexa DC.: Surinarne, Uw 1744 and Uw 2529. -M. JaUax DC.: Surinarne, Uw 1744 and Venezuela, Uw 1887 and Uw

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12195, - M. grandis McVaugh: Guyana, Uw 21510, - M. guianensis DC. var. guianensis: Gu­ yana, Uw 21634. - M. inaequiloba (DC.) D. Legrand: Guyana, Uw 21514 and Uw 21540. -M. multiflora (Larn.) DC.: Brazil, Kw 22097. -M. pyrifolia (Desv. ex Harn.) Nied.: Surinarne, Uw 335. -M. servata McVaugh: Guyana, Uw 1006. -M. cf. splendens (Swartz) DC.: Kw 71381 and Uw 1466. - M. subobliqua (Benth.) Nied.: Guyana, UwlO04 and FHOw 14789. - M. sylvatica (G.Mey.) DC.: Surinarn, Uw 2528. - M. tomentosa (AubI.) DC.: Guyana, Uw 32229. The wood sampies were boiled in water. Transverse and longitudinal (tangential and radial) sections were then cut at 20 - 25 /JIll on a Reichert OME sliding microtome, stained in 1% safranin in 50% alcohol and 1% aqueous alcian blue, taken through an alcohol series to 100% ethanol, cleared in histoclear and mounted in euparal. For scanning electron microscopy (SEM), wood sections were split longitudinally and air-dried. Dried specimens were then sputter-coated with gold and viewed in radial longitudinal section using a Cambridge 240 SEM at 18 K v. Photomicrographs were taken at various magnifications using SEM and light mi­ croscopy. The IAWA List of Features for Hardwood Identification (IAWA Committee 1989) was used to interpret the microscopical observations.

GENERAL DESCRIPTION OF THE SUBTRIBE

Wood: diffuse porous. Vessels (Figs. 1-4,9-10): typically solitary (Figs. 1-4), perforations simple (Fig. 9), intervessel pits alternate, vestured (Fig. 10); vessel to ray pitting of same type as the intervascular pitting. Fibres (Figs. 11-12): mostly thick-walled with bordered pits in both tangential and radial walls, some of which are vestured in most species. Parenchyma (Figs. 1- 5): scanty paratracheal, diffuse and/or diffuse-in-aggregates forming complete or interrupted bands, in strands of 4 - 8 (3 -10) cells. Rays (Figs. 6 - 8): 1- 3(- 4 )-seriate, body ray cells procumbent with over 4 rows of square and / or upright marginal cells, some chambered. Disjunctive ray parenchy­ ma cell walls present (Fig. 8).

OBSERVATIONS AND DISCUSSION

The wood anatomy of the four genera (Figs.l-14, Table 1) fits in weIl with the gen­ eral descriptions of the wood of the Myrtaceae by Metcalfe and Chalk (1950), Record and Hess (1943) and Van Vliet and Baas (1984). These four genera do not occur in the southwest Pacific (Ingle & Dadswell 1953), but they share many characters with genera that do occur there. Axial parenchyma distribution (Figs.l- 5) has some diagnostic value. Calyptran­ thes (Fig. 3) has parenchyma that is scanty paratracheal and diffuse-in-aggregates and in continuous tangential bands up to three cells wide. In Gomidesia the paren­ chyma is also scanty paratracheal and diffuse-in-aggregates (Figs. 1, 2), but rarely banded, and G. affinis (Fig. 1) has only diffuse parenchyma. The parenchyma of Mar­ lierea (not illustrated) is very similar to that of Calyptranthes (Fig. 3), although one

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Fig. 1. Gomidesia affinis, growth rings indistinct and rnarked by thick-walled and radially flat­ ten-ed latewood fibres, vessels exclusively solitary and axial parenchyrna scanty paratracheal and diffuse. - Fig. 2. G. tijucensis, vessels exclusively solitary and axial parenchyma scanty paratracheal and diffuse-in-aggregates. - Fig. 3. Calyptranthes lucida, axial parenchyrna scanty paratracheal and diffuse-in-aggregates, in continuous and discontinuous narrow bands or lines up to three cells wide. Thick-walled fibres. - Fig. 4. Myrcia inaequiloba, axial parenchyma scanty paratracheal and diffuse-in-aggregates, and in continuous or discontinuous bands 3 or more cells wide. - Scale bar = 100 !ill1.

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Crystal presence and distribution mayaiso have diagnostic value (Figs, 13 & 14). No crystals were observed in Gomidesia. There were several crystals of different sizes per non-chambered axial parenchyma cell in two Calyptranthes species (Fig. 13) and of the same size in some Marlierea species. Single prismatic crystals were

Fig. 5. Myrcia inaequiloba, axial parenchyma in continuous or discontinuous bands 3 or more cells wide, dark contents in axial parenchyma and ray cells, and thick-walled fibres. - Fig. 6. Gomidesia tijucensis, rays 1-3 cells wide, with margins of upright cells. - Fig. 7. Myrcia fallax, body ray cells procumbent with more than four rows of upright and square marginal cells. - Fig. 8. Marlierea spruceana, disjunctive ray parenchyma cell walls. - Scale bars of Figs. 5, 6 & 7 = 100 /Jill, of Fig. 8 = 25 /Jill.

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Fig. 9. Myrcia multiflora, two vessels showing both inner and outer walls with vestured pits and simple perforation plate. - Fig. 10. Gomidesia anacardiifolia, outer vessel wall with vestured pits. - Fig. 11. G. anacardiifolia, fibres with distinct1y vestured pits. - Fig. 12. Marlierea syl­ vatica, fibres with distinctly bordered pits, which are not vestured. - Scale bars = 20 !illl.

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Fig. 13. Calyptranthes pileata, different size classes of prismatic crystals in the same cell in some axial parenchyma cells. Note also the bordered pits in adjacent fibres. Scale bar = 25 /JIll. - Fig. 14. Myrcia tomentosa, prismatic crystals, one per chamber, in axial parenchyma. Scale bar = 20 /JIll.

Helical wall thickenings are found in vessels and/or fibres in eight genera of Myrta­ ceae, including four species of Myrcia (Schmid & Baas 1984). We found them in the fibres in only one species (M. bracteata), and could not find them in any vessels, so the character is of no diagnostic value at the genus level. We also saw only non-septate fibres in Marlierea, whereas Metcalfe and Chalk observed occasional septate fibres in this genus. They described some rays up to eight cells wide in Gomidesia, much wider than any found in this study. Although vestured pits are generally thought to be ubiqui­ tous in the family (Figs. 9 -11), the bordered pits in fibre-tracheids of some species, e.g. Marlierea sylvatica (Fig. 12), are not vestured. The presence or absence ofvestur­ ing in fibre-tracheids may be worth surveying in greater detail. The conclusion we have to reach is that the four genera cannot be reliably sepa­ rated on the basis ofwood anatomy alone, and that McVaugh's (1968) opinion that the genera could be amalgamated is supported by our observations. The wood structure seems to be as conservative as the morphology, and no single character or character combination seems to be consistently distributed or to occur in enough species within each genus to be diagnostic at the generic level. Some of the differences observed may be related to habitat preferences but, since the sampIes were obtained from wood collections and had little associated ecological information, the environmental condi­ tions are unknown.

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ACKNOWLEDGEMENTS

This investigation was supported by a grant from The Margaret Mee Foundation. We are very grate­ ful to all colleagues who provided wood sampIes and/or microscope slides for this study: J. Koek-Noorman and B.J.H. ter Welle (Utrecht, The Netherlands), P. Baas and R. Klaassen (Lei­ den, The Netherlands), I. Gourlay (Oxford, England) and J. Chimelo (Silo Paulo, Brazil). Special thanks go to N.L. de Menezes, D.F. CutIer, H. Wilkinson, P. Rudall and T. Lawrence for their help and advice. The Kew Photographie Department processed and printed the photos.

REFERENCES

Barbosa, 0., C. Mainieri, R G. Montagna & O. C. de Negreiros. 1977/78. Identificacao e fenologia de especies arboreas da Serra da Cantareira (Silo Paulo). Silvicultura, Silo Paulo 1-12: 1-8. Berg, O. 1855/56. Revisio Myrtacearum Americae. Linnaea 27: 1-472. Brummitt, R K. 1992. Vascular plant families and genera. Royal Botanic Gardens, Kew. Detienne, P. & P. Jacquet. 1983. Atlas d'identification de Bois de l' Amazonie et des regions voisines. Centre Technique Forestier Tropical. Nogent-sur-Marne, France. Detienne P., P. Jacquet & A. Mariaux. 1982. Manual d'identification des bois tropicaux, Tome 3. Guyane Franc,;aise. Centre Technique Forestier Tropical. Nogent-sur-Marne, France. IAWA Committee. 1989. IAWA List of microscopic features for hardwood identification. IAWA Bull. n.s. 10: 219-332. Ilic, J. 1991. CSIRO atlas ofhardwoods. Springer-Verlag, Berlin, NewYork, etc. Ingle, H. D. & H. E. Dadswell. 1953. The anatomy of the timbers of the south-west Pacific area. III. Myrtaceae. Austral. J. Bot. 1: 353-401. Landrum, L.R 1981. A monograph of the genus Myrceugenia (Myrtaceae). Flora Neotropica Monograph 29: 1-137. New York Botanical Garden. Mabberley, D.J. 1987. The Plant-book. A portable dictionary of the higher plants. Cambridge University Press, Cambridge, UK. McVaugh, R. 1968. The genera of American Myrtaceae-An interim report. Taxon 17: 354-418. Metcalfe, C. R & L.Chalk. 1950. Anatomy of the dicotyledons. Clarendon Press, Oxford. Record, S. J. & RW. Hess. 1943. Timbers of the New World. Yale University Press, New Haven, USA. Schmid, R & P. Baas. 1984. The occurrence of scalariform perforation plates and helical ves­ seI wall thickenings in wood ofMyrtaceae. IAWA Bull. n.s. 5:197-215. Stern, W. L. 1988. Index Xy1ariorum, institutiona1 wood collections of the world. IAWA Bull. n.s. 9: 203-332. Van Vliet, G. J. C. M. & P. Baas. 1984. Wood anatomy and classification of the Myrtales. Ann. Missouri Bot. Gard. 71: 783-800.

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