See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/233916648 Foliar anatomy of the subfamily Myrtoideae (Myrtaceae) Article in Australian Journal of Botany · January 2009 DOI: 10.1071/BT07176 CITATIONS READS 13 186 3 authors, including: Proença Sl 7 PUBLICATIONS 97 CITATIONS SEE PROFILE M. Graça Sajo São Paulo State University 76 PUBLICATIONS 703 CITATIONS SEE PROFILE All content following this page was uploaded by M. Graça Sajo on 09 May 2014. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. CSIRO PUBLISHING www.publish.csiro.au/journals/ajb Australian Journal of Botany, 2009, 57, 148–161 Foliar anatomy of the subfamily Myrtoideae (Myrtaceae) C. M. V. Cardoso A,B, S. L. Proença A and M. G. Sajo A A Departamento de Botânica, Instituto de Biociências, Universidade Estadual Paulista – UNESP, C.P. 199, 13506-900, Rio Claro, SP, Brazil. B Corresponding author. Email: cmviana@hotmail.com Abstract. The foliar structure of 44 species of Myrtoideae Nied. (Myrtaceae) was described to characterise the anatomy of the leaves in this subfamily and also to recognise particular features in each genus and/or subtribe. In the present study, nine genera of the subtribe Myrtinae, five genera of the subtribe Myrciinae and eight genera of the subtribe Eugeniinae were examined. All of them have dorsiventral and hypostomatic leaves, with stomata slightly protruded in relation to other epidermal cells; the leaves also present secretory cavities, idioblasts containing druses and vascular bundles with phloem on both adaxial and abaxial sides. Some surface features have diagnostic value for all genera of these three subtribes, such as the percentage of palisade parenchyma, the presence or absence of an adaxial hypodermis, the occurrence of an extension to the vascular bundle sheath, and the shape and position of the vascular system of the midrib. These features are described for each of the species studied and the results are discussed in a taxonomical context. Introduction Myrtaceae A.L.Juss. is included in the order Myrtales (Soltis et al. 2005) where all representatives present vestured pits in the vessel elements of the secondary xylem, and bicollateral vascular bundles (with phloem on both adaxial and abaxial sides) (Metcalfe and Chalk 1979; Keating 1984; Conti et al. 1996, 1997). Within this order, Vochysiaceae, Combretaceae, Melastomataceae, Alzateaceae and Penaeaceae share with Myrtaceae the occurrence of peeling bark and of tracheary sclereids situated in the vascular endings. However, molecular studies (Conti et al. 1996, 1997; Wilson et al. 2001) have pointed out Vochysiaceae as the only sister-group of Myrtaceae, together with Heteropyxidaceae and Psiloxylaceae. Myrtaceae includes 3100 species and ~140 genera, divided into two subfamilies, namely Leptospermoideae and Myrtoideae (Judd et al. 1999). The first occurs in Australia and in Polynesia and Myrtoideae predominate in tropical and subtropical America (Cronquist 1981; Heywood 1993). Myrtoideae comprises only one tribe, Myrteae DC., divided into three subtribes, i.e. Myrtinae, Myrciinae, and Eugeniinae, according to their embryo features (Berg 1855, 1857). Although regarded as one of the most important and diversified families in the Brazilian ecosystems (Mori et al. 1983; Freire 1990; Oliveira-Filho and Carvalho 1993; Fabris and Cesar 1996; Soares-Silva 2000), the leaf anatomy of the Myrtaceae has not been comprehensively described yet. Some studies focus on the leaf anatomy of a single species (Backes 1971; Behar 1971; Moura 1971; Palhares 2003), whereas others describe the leaf structure of some Eugenia species (Du Plessis and Van Wik 1982; Khatijah et al. 1992; Fontenelle et al. 1994; Costa et al. 1995; Haron and Moore 1996; Cardoso and Sajo 2004). In a study on the hydric balance of cultivated species, Ferri (1971) described the foliar anatomy of
CSIRO 2009 eight Myrtaceae and in a comprehensive analysis Klucking (1988) illustrated the foliar venation patterns of 85 genera in this family. The present study analyses the leaf structure of 44 species in 22 of the 23 American genera that compose the subfamily Myrtoideae, to (1) characterise the morphology and anatomy of these organs, (2) point out particular features in each subtribe and/or genus and (3) compare the results with those described for the order Myrtales. Materials and methods The leaves were collected in their natural habitat in the cerrado vegetation in Itirapina (SP), Botucatu (SP) and Brasília (DF) and in semi-deciduous seasonal forest in Sete Barras (SP) and Londrina (PR). Part of the material was fixed in formalin : acetic acid : alcohol (FAA) and stored in 50% alcohol, and the other part was prepared for the herbarium and included in the herbaria HRCB (Herbarium Rioclarense), UB (Herbarium of the University of Brasília), and HUEL (Herbarium of the State University of Londrina). The material of Accara elegans (DC) Landrum was donated by the Herbarium UB and that of Calycolpus legrandii Mattos by the herbarium HUEFS (Herbarium of the State University of Feira of Santana). Table 1 provides a list of the species studied, together with the collector number and the Herbarium. Data for the species not listed in Table 1 were obtained from the literature, and are inserted in the other tables and discussed in the text. The median region of the leaves was transversally sectioned in the midrib and in the intercostal region. The sections were cleared with a commercial solution of sodium hypochlorite (20%), stained with a solution of safranin (1%) and Astra blue (1%) and mounted on semi-permanent slides with glycerin gelatin (Kaiser 1880 cited in Kraus and Arduin 1997). Fresh material 10.1071/BT07176 0067-1924/09/020148 Foliar anatomy of Myrtoideae Australian Journal of Botany 149 Table 1. A list of the studied material, respective collection numbers and herbarium details FUEL, Herbarium of the Universidade Estadual de Londrina; HRCB, Herbarium Rioclarense; HUEFS, Herbarium of the Universidade Estadual de Feira de Santana; UB, Herbarium of the Universidade de Brasília Genus, number of species in BrazilA Acca 1 Accara 1 Blepharocalix 2 Calycolpus 5 Campomanesia 24 Mosiera 1 Myrrhinium 1 Pimenta 1 Psidium 70 Calyptranthes 100 Complex Gomidesia, Marlierea, Myrcia 400 Myrceugenia 40 Complex Calycorectes, Eugenia, Hexachlamys 350 Myrcianthes 3 Myrciaria 30 Neomitranthes 5 Plinia 20 Siphoneugena 8 A Studied species Collector number/Herbarium Subtribe Myrtinae Acca sellowiana (O.Berg) Burret Accara elegans (DC.) Landrum Blepharocalyx salicifolius (Kunth.) O.Berg Calycolpus legrandii Mattos Campomanesia guazumifolia (Cambess.) O.Berg C. pubescens (DC.) O.Berg Campomanesia sp. Mosiera prismatica (D.Legrand) Landrum Myrrhinium atropurpureum Schott Pimenta pseudocaryophyllus (Gomes) Landrum Psidium australe Cambess. P. guineense Sw. P. firmum O.Berg, P. myrsinoides O.Berg Subtribe Myrciinae Calyptranthes concinna DC. C. widgreniana O.Berg Gomidesia lindeniana O.Berg G. spectabilis (DC.) O.Berg Marlierea eugeniopsoides (D.Legrand & Kausel) D.Legrand M. obscura O.Berg Myrcia bella Cambess. M. laruotteana Cambess. M. lingua (O.Berg) Mattos & D.Legrand M. rostrata DC. M. tomentosa (Aubl.) DC. M. torta DC. Subtribe Myrciinae Myrceugenia euosma (O.Berg) Legrand M. hatschbachii Landrum M. ovata Hook. & Arn. Subtribe Eugeniinae Calycorectes australis D.Legrand C. psidiiflorus (O.Berg) Sobral Eugenia aurata O.Berg E. bracteata Rich. E. klotzschiana O.Berg E. punicifolia (Kunth) DC. E. pyriformis Cambess. Hexachlamys itatiaiensis Mattos Myrcianthes pungens (O.Berg) D.Legrand Myrciaria cuspidata O.Berg M. delicatula (DC.) O.Berg M. tenella (DC.) O.Berg Neomitranthes glomerata (D.Legrand) D.Legrand Plinia rivularis (Cambess.) A.D.Rotman P. trunciflora (O.Berg) Kausel Siphoneugena densiflora O.Berg Irwin et al. (UB 31132) Irwin et al. (UB 29294) Soares-Silva 1125 (UB) Viana et al. 02 (HUEFS) Soares-Silva et al. 440 (FUEL) Soares-Silva and Cardoso 1141 (UB, HRCB) Cardoso 30 (HRCB) Soares-Silva et al. 467 (FUEL) Soares-Silva and Chagas e Silva 542 (FUEL) Soares-Silva and Cardoso 1136 (UB, HRCB) Cardoso (HRCB 34601) Cardoso (HRCB 34602) Soares-Silva and Cardoso 1144 (UB, HRCB) Soares-Silva and Cardoso 1140 (UB, HRCB) Soares-Silva et al. 597 (FUEL, UB) Soares-Silva (UB) Soares-Silva and Cardoso 1138 (UB) Castro 04 (HRCB) Zipparro 1764 (HRCB) Zipparro 2058 (HRCB) Cardoso (HRCB 34606) Cardoso (HRCB 34605) Cardoso 33 (HRCB) Cardoso 41 (HRCB) Soares-Silva and Cardoso 1137 (UB) Soares-Silva and Cardoso 1127 (UB) Soares-Silva et al. 3400 (FUEL) Soares-Silva et al. 683 (FUEL, UB) Chagas and Silva et al. 2158 (FUEL, UB) Zipparro 2163 (HRCB) Chagas and Silva 1449 (FUEL) Cardoso 35 (HRCB) Soares-Silva 1126 (UB) Cardoso 36 (HRCB) Cardoso (HRCB 34603) Cardoso (HRCB 34606) Chagas and Silva 1722 (FUEL) Constantino (HRCB 26724) Soares-Silva et al. 442 (FUEL) Soares-Silva 422 (FUEL) Soares-Silva et al. 441 (FUEL) Zipparro 804 (HRCB) Soares-Silva et al. 504 (FUEL) Soares-Silva 178 (FUEL) Soares-Silva and Cardoso 1134 (UB) Landrum and Kawasaki (1997). was used to test the presence/absence of phenolic compounds (Johansen 1940), starch, lignin (Johansen 1940) and lipids (Sass 1951) and the chemical nature of the crystals (Chamberlain 1932, modified, cited in Kraus and Arduin 1997). The percentage of palisade parenchyma was measured in relation to mesophyll thickness, on photomicrographs of the same magnification. The epidermal cell sizes of the adaxial and abaxial surfaces were only roughly compared. Even 150 Australian Journal of Botany C. M. V. Cardoso et al. though these comparisons were somewhat subjective, the size differences were large enough to allow reliable comparisons to be made. Results Lamina All the specimens of the three subtribes presented dorsiventral and hypostomatic leaves. Tables 2–4 list the principal features observed for the leaves studied. In the cross-section, the onelayered epidermis is formed by square to rectangular cells. In most Myrtinae (Table 2), Myrciinae (Table 3) and Eugeniinae (Table 2), the epidermal cells are bigger on the adaxial than on the abaxial surface (Figs 1A–F, 2B–E, 3A–D), although some species of the three subtribes have leaves with epidermal cells of approximately the same dimension on both surfaces (Tables 2, 3, Figs 1G, 2A). The adaxial epidermal cells usually present a thickened outer periclinal wall (Figs 1A–E, G, 2D, E, 3A–C), although in Hexachlamys itatiaiensis (Fig. 3D), of the subtribe Eugeniinae, only the inner periclinal wall is thickened and in Blepharocalyx (Fig. 1F) and Psidium australe, of the subtribe Myrtinae, both periclinal walls are thickened. Stomata appear slightly protruding in relation to the epidermis, and the guard cells show projections, rising from a cuticle (Fig. 1B). The leaves of Myrceugenia ovata (Fig. 2D) and M. hatschbachii, of the subtribe Myrciinae, as well as those of Table 2. Features observed in Myrtinae and Eugeniinae leaf blades AB = abaxial, AD = adaxial, B = lobed cells, E = sheath extension Species Subtribe Myrtinae Acca sellowiana Accara elegans Blepharocalyx salicifolius Calycolpus legrandii Campomanesia guazumifolia C. pubescens Campomanesia sp. Mosiera prismatica Myrrhinium atropurpureum Pimenta pseudocaryophyllus Psidium australe P. cattleianumA P. firmum P. guayavaB P. guineense P. multiflorumC P. myrsinoides Subtribe Eugeniinae Calycorectes. australis C. psidiiflorus Eugenia aurata E. bracteata E. cupreaD E. klotzschiana E. punicifolia E. pyriformis E. sulcataE E. unifloraF Hexachlamys itatiaiensis Myrcianthes pungens Myrciaria cuspidata M. delicatula M. tenella Neomitranthes glomerata Plinia rivularis P. trunciflora Siphoneugena densiflora A E Collection site Epidermis Simple Cell size trichomes Adaxial hypodermis Mesophyll Palisade Spongy parenchyma parenchyma % No. of (arrangement) layers Vascular bundle sheath Woods Campo rupestre Cerrado Restinga Woods Cerrado Cerrado Woods Campo sujo Cerrado Cerrado Woods Cerrado Woods Cerrado Cerrado Cerrado Abaxial Absent Absent Absent Both Both Both Absent Absent Abaxial Both Absent Both Both Both Abaxial Absent AD > AB AD = AB AD > AB AD > AB AD > AB AD > AB AD = AB AD > AB AD > AB AD = AB AD > AB AD > AB AD > AB AD > AB AD > AB AD > AB AD > AB Absent Absent Absent Absent Absent 1 or 2 layers 1–3 layers Absent Absent 2 or 3 layers Absent 1 layer 1 or 2 layers 2 or 3 layers 2 or 3 layers Various 1 or 2 layers 25–30 25–30 25–30 20 50 50 40 25–30 20 50 25–30 30 50 100 50 30 50 4 or 5 1 1 1 1 2 or 3 1 or 2 2 1 or 2 2 or 3 1 1 or 2 2 or 3 Various 2 or 3 2 2 or 3 Loose Loose Loose (B) Compact Compact Compact Loose (B) Compact Compact Loose Loose (B) Compact Compact Absent Compact Compact Compact Parenchyma Parenchyma Parenchyma Parenchyma Sclerenchyma (E) Parenchyma (E) Sclerenchyma (E) Parenchyma Parenchyma Sclerenchyma (E) Parenchyma Parenchyma Parenchyma Sclerenchyma Parenchyma Absent Parenchyma Woods Woods Cerrado Cerrado Woods Cerrado Cerrado Cerrado Restinga Woods Cerrado Woods Woods Woods Woods Woods Woods Woods Cerrado Absent Absent Absent Absent Both Adaxial Adaxial Both Absent Absent Both Absent Absent Absent Adaxial Absent Absent Absent Absent AD > AB AD > AB AD > AB AD > AB AD = AB AD > AB AD > AB AD > AB AD > AB AD = AB AD > AB AD = AB AD > AB AD = AB AD > AB AD = AB AD > AB AD > AB AD > AB Absent Absent Absent Absent Absent Absent Absent Absent Absent Absent Absent 1 layer Absent Absent Absent Absent Absent Absent Absent 20 25–30 25–30 20 25–30 40–50 40–50 25–30 25–30 25 30–40 20 30 40–50 25–30 20 40–50 30 20 1 2 2 2 or 3 1 2 2 1 1 1 1 1 2 2 1 1 2 1 1 Loose (B) Loose (B) Compact Loose (B) Loose Compact Compact Loose (B) Loose Loose Compact Loose (B) Loose (B) Compact Compact Compact Compact Compact Compact Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic No information Parenchymatic (E) Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Parenchymatic Boeger and Wisniewski (2003); Arruda and Fontenelle (1994); BFerri (1971) and Souza (1971); CBackes (1971) and Ferri (1971); DCallado (1997); Machado et al. (1988); FBehar (1971). Foliar anatomy of Myrtoideae Australian Journal of Botany 151 Table 3. Features observed in Myrciinae leaf blades AB = abaxial, AD = adaxial, B = lobed cells, E = sheath extension Species Subtribe Myrciinae Calyptranthes concinna C. widgreniana Gomidesia fenzlianaA G. lindeniana G. martianaA G. nitidaB G. spectabilis Marlierea eugeniopsoides M. obscura M. suaveolensC Myrceugenia euosma M. hatschbachii M. ovata Myrcia bella M. laruotteana M. lingua M. rostrata M. tomentosa M. torta A Collection site Woods Cerrado Restinga Cerrado Restinga Woods Woods Woods Woods Woods Várzea Várzea Campo Cerrado Cerrado Cerrado Cerrado Cerrado Cerrado Epidermis Simple Cell size trichomes Absent Absent Both Both Both Abaxial Both Absent Absent Abaxial Secretor abaxial Absent Absent Abaxial Absent Absent Both Both Absent AD > AB AD > AB AD = AB AD > AB AD > AB AD = AB AD = AB AD = AB AD > AB AD > AB AD > AB AD > AB AD > AB AD > AB AD > AB AD > AB AD > AB AD > AB AD = AB Adaxial hypodermis Absent Absent 1 layer Absent Absent Absent Absent Absent Absent Absent 1 layer Absent Absent Absent Absent Absent Absent Absent Absent Mesophyll Palisade Spongy parenchyma parenchyma % No. of (arrangement) layers 25–30 25–30 25–30 50 25–30 25–30 25–30 20 25–30 25–30 50–60 50 25–30 40 40–60 50 50 50–60 50 2 1 1 or 2 1 or 2 1 1 1 1 1 1 3 or 4 2 or 3 2 1 2 2 1 2 2 Compact Compact Loose Loose (B) Loose Loose Loose Loose (B) Loose (B) Loose Loose (B) Loose (B) Loose Compact Loose Compact Compact Compact Loose Vascular bundle sheath Parenchyma Parenchyma (E) Sclerenchyma (E) Parenchyma Parenchyma Parenchyma Parenchyma (E) Parenchyma Parenchyma No information Parenchyma Parenchyma Parenchyma Parenchyma (E) Parenchyma (E) Parenchyma (E) Parenchyma (E) Parenchyma (E) Parenchyma Fontenelle et al. (1993); BGomes and Neves (1997); CCallado (1997). Myrciaria cuspidata, of the subtribe Eugeniinae, present large substomatic chambers, often shared by more than one stoma. Simple trichomes (Figs 1D, E, 2A) are common on the leaves of the three subtribes and occur either on both surfaces or only on the abaxial surface (Tables 2, 3). Secretory trichomes occur only on the abaxial surface of the Myrceugenia euosma leaf and are formed by papillose cells with thickened walls (Fig. 2E). A hypodermis with one or many layers of cells occurs adjacent to the adaxial surface (Fig. 1C–E, G) of some leaves (Tables 2, 3). In Myrceugenia euosma (Fig. 2E), of the subtribe Myrciinae, and in Myrcianthes pungens, of the subtribe Eugeniinae, this tissue is one-layered and its cells have thickened periclinal walls. The percentage of mesophyll occupied by the palisade parenchyma varies in the three subtribes (Tables 2, 3), being 20% (Figs 1B, 3C), 25–30% (Figs 1A, F, 2A, D, 3A), 30–40% (Fig. 3D) or 40–60% (Figs 1C–E, G, 2B, C, E, 3B). The number of layers forming this tissue also varies inside the three subtribes (Tables 2, 3), being one-layered (Figs 1F, 2A, 3A, C, D), one- or two-layered (Fig. 1B, G), two-layered (Figs 1A, 2B–D, 3B), two or three-layered (Fig. 1C–E) or more than three-layered (Fig. 2E). In addition, the structure of the spongy parenchyma is not constant within the three subtribes (Tables 2, 3), consisting of both irregular cells compactly arranged (Figs 1A–D, 2B, 3A–D) and lobed cells with many intercellular spaces (Figs 1E–G, 2A, C–E). In the three subtribes, the smaller vascular bundles are collateral and surrounded by a sheath of parenchymatous cells (Tables 2, 3, Figs 1A, 2A–D, 3A). In some cases, the sheath cells are sclerified (Fig. 1E, G; Tables 2, 3). In some leaves, there are sheath extensions protruding to both surfaces (Figs 1E, G, 2B; Tables 2, 3), while in others these sheaths extend only to the adaxial surface (Table 3, Fig. 2A, C). In the non-lignified tissues of the mesophyll there are rhombohedral, prismatic crystals and idioblasts containing druses in all leaves studied (Figs 1C–E, 3B, C). In those of Accara, Blepharocalyx, Calycolpus, Campomanesia pusbescens, Myrrhinium and Psidium (subtribe Myrtinae), Marlierea and Gomidesia (subtribe Myrciinae), and Eugenia, Myrciaria, Neomitranthes and Siphoneugena (subtribe Eugeniinae), there are phenolic compounds inside the cells close to the abaxial or adaxial surfaces. Secretory cavities lined by a one-layred epithelium occur close to the abaxial or adaxial surfaces in all species (Figs 1C, 2B, 3C, D). Midrib In the midrib region, the adaxial leaf surface is flattened (Figs 4A–C, 5A, B, 6A) in most species of the three subtribes (Tables 4, Table 5). However, in some the surface is grooved (Tables 4, 5, Figs 5C, 6B) or convex (Tables 4, 5, Figs 4D, E, 5D, 6C, D), and in Mosiera, of the subtribe Myrtinae, the adaxial surface presents an acute projection (Table 4, Fig. 4F). The vascular bundle is level with the mesophyll (Figs 4F, 5A, C, 6A–D) in most of the species studied (Tables 4, 5), except in some Myrtinae and Myrciinae (Figs 4A, D, E, 5D, Tables 4, 5). All leaves have a vascular system where the midrib is composed of a central xylem, with phloem in adaxial and abaxial positions (bicollateral). In most species of the three subtribes, the vascular system is in the form of an arc with open extremities, and without phloem confluence (Figs 4A, B, D, 5C, 6A–C, Tables 4, 5). 152 Australian Journal of Botany C. M. V. Cardoso et al. Table 4. Features observed in the midrib region of Myrtinae and Eugeniinae leaves AB = abaxial, AD = adaxial Species Subtribe Myrtinae Acca sellowiana Accara elegans Blepharocalyx salicifolius Calycolpus legrandii Campomanesia guazumifolia C. pubescens Campomanesia sp. Mosiera prismatica Myrrhinium atropurpureum Pimenta pseudocaryophyllus Psidium australe P. cattleianumA P. firmum P. guayavaB P. guineense P. multiflorumC P. myrsinoides Subtribe Eugeniinae Calycorectes australis C. psidiiflorus Eugenia aurata E. bracteata E. cupreaD E. klotzschiana E. punicifolia E. pyriformis E. sulcataE E. unifloraF Hexachlamys itatiaiensis Myrcianthes pungens Myrciaria cuspidata M. delicatula M. tenella Neomitranthes glomerata Plinia rivularis P. trunciflora Siphoneugena densiflora A Collection place Adaxial surface Arc Position Woods Campo rupestre Cerrado Restinga Woods Cerrado Cerrado Woods Campo sujo Cerrado Cerrado Woods Cerrado Woods Cerrado Cerrado Cerrado Grooved Flat Flat Grooved Convex Flat Flat Prominent Grooved Convex Flat Flat Flat Grooved Flat Grooved Convex Open Open Curved Curved Open Open Open Curved Open Open Open Open Open Open Open Open Open Dislocated Level Level Level Dislocated Dislocated Dislocated Level Dislocated Level Dislocated Level Dislocated Dislocated Dislocated Level Level Woods Woods Cerrado Cerrado Woods Cerrado Cerrado Cerrado Restinga Woods Woods Woods Woods Woods Woods Woods Woods Woods Woods Flat Flat Convex Flat Grooved Convex Flat Convex No information Flat Flat Flat Grooved Flat Flat Convex Flat Flat Convex Open Open Open Open Open Open Open Open Open Open Open Open Open Open Open Curved Open Open Ring Level Level Level Level Level Level Level Level Level Level Level Level Level Level Level Level Level Level Level Vascular system Phloem Confluence Proportion No No No No No No No No Yes Yes No Yes Yes Yes No No No AD > AB AD > AB AD > AB AD = AB AD > AB AD > AB AD > AB AD > AB AD = AB AD > AB AD = AB AD = AB AD = AB AD = AB AD > AB AD > AB AD > AB Sclerenchymatic sheath Continuous Continuous Continuous Continuous (AB) Discontinuous Continuous Continuous Discontinuous Continuous (AD) Continuous Discontinuous Continuous Continuous Continuous Discontinuous Continuous Discontinuous No AD > AB Discontinuous (AD) No AD > AB Continuous No AD < AB Continuous No AD = AB Continuous No AD = AB Continuous Yes AD > AB Discontinuous (AD) No AD > AB Continuous Yes AD > AB Continuous No information No information Discontinuous (AD) No AD > AB Continuous No AD > AB Discontinuous Yes AD > AB Continuous No AD < AB Continuous No AD = AB Continuous No AD > AB Continuous Yes AD < AB Continuous No AD > AB Continuous No AD > AB Continuous Yes AD = AB Continuous Arruda and Fontenelle (1994); BFerri (1971) and Souza (1971); CBackes (1971) and Ferri (1971); DCallado (1997); EMachado et al. (1988); FBehar (1971). However, in some specimens, the adaxial and abaxial phloem meet at the arc extremities and completely surround the xylem (Figs 4E, 5B, Tables 4, 5). The ends of the vascular system are curved inward and form two islands of xylem completely surrounded by phloem in certain taxa of the subtribes Myrtinae (Blepharocalyx (Fig. 4C), Mosiera (Fig. 4F) and Calycolpus), Myrciinae (Myrcia laruotteana (Fig. 5A), Myrcia tomentosa (Fig. 5D) and Marlierea obscura) and Eugeniinae (Neomitranthes glomerata and Calycorectes australis). The vascular system forms an arc of xylem, surrounded abaxially by phloem and adaxially by phloem interspersed with xylem in some Myrtinae (Campomanesia sp. (Fig. 4A) and Psidium firmum), Myrciinae (Gomidesia spectabilis (Fig. 5B), Gomidesia lindeniana, Calyptranthes widgreniana, Marlierea eugeniopsoides and Myrcia rostrata) and Eugeniinae (Hexachlamys itatiaiensis (Fig. 6A) and Calycorectes psidiiflorus). In Gomidesia spectabilis, of the subtribe Myrciinae, there is a central medulla in the vascular bundle (Fig. 5B), whereas in Siphoneugena densiflora (Fig. 6D), of the subtribe Eugeniinae, the vascular system is formed by a ring of xylem, surrounded externally by phloem and internally by phloem interspersed with xylem. The adaxial phloem is more developed than the abaxial one in most of the species studied (Figs 4A–F, 5A, B, D, 6A, Tables 4, 5), although both appear in the same proportion (Fig. 6C, D) in some Myrtinae (Table 4) and Eugeniinae. Abaxial phloem that is more developed than the adaxial one (Figs 5C, 6B) occurs only in leaves of some Myrcinae and Eugeniinae. In all the leaves studied, the pericyclic cells are sclerified and surround the vascular tissues of the midrib. In most species of the Foliar anatomy of Myrtoideae Australian Journal of Botany 153 (A) (B) (C) (D) (E ) (G) (F ) Fig. 1. Myrtinae leaves in cross-section. (A) Mosiera prismatica, with palisade parenchyma occupying 25–30% of the mesophyll and compact spongy parenchyma; vascular bundles are surrounded by a sheath of parenchymatous cells. (B) Myrrhinium atropurpureum, with palisade parenchyma occupying 20% of the mesophyll and spongy parenchyma compactly arranged. (C) Psidium firmum, showing adaxial hypodermis with one layer of cells, palisade parenchyma occupying 50% of the mesophyll and compact spongy parenchyma. (D) Psidium guineense, showing adaxial hypodermis with three layers of cells, palisade parenchyma occupying 50% of the mesophyll and compact spongy parenchyma; note the tector trichome on the abaxial surface. (E) Pimenta pseudocaryophyllus, showing adaxial hypodermis with two or three layers of cells, palisade parenchyma occupying 50% of the mesophyll and spongy parenchyma with many intercellular spaces; vascular bundle with sheath extension protrudes to both surfaces. (F) Blepharocalyx salicifolius, showing epidermal cells of the adaxial surface with both periclinal walls thickened, and palisade parenchyma occupying 25–30% of the mesophyll. (G) Campomanesia sp., with epidermal cells of approximately the same dimension on both surfaces, adaxial hypodermis with one or two layers of cells and vascular bundle with sheath extensions to both surfaces. Scale bars = 20 mm (A), 30 mm (B, D–G) and 70 mm (C). 154 Australian Journal of Botany C. M. V. Cardoso et al. (A) (B) (C) (D) (E ) Fig. 2. Myrciinae leaves in cross-section. (A) Gomidesia spectabilis, with epidermal cells of approximately the same dimension on both surfaces, a layer of palisade parenchyma occupying 25% of the mesophyll, spongy parenchyma loosely arranged and vascular bundle with sheath extension to the adaxial surface; note the tector trichome on the abaxial surface. (B) Myrcia tomentosa, showing palisade parenchyma occupying 50–60% of the mesophyll and compact spongy parenchyma and vascular bundle with sheath extension protruding to both surfaces. (C) Myrcia laruotteana, with palisade parenchyma occupying 40% of the mesophyll and spongy parenchyma with many intercellular spaces; sheath extension of the vascular bundle protrudes to the adaxial surface. (D) Myrceugenia ovata, with palisade parenchyma occupying 25% of the mesophyll and spongy parenchyma with many intercellular spaces; note the presence of large substomatal chambers and a vascular bundle surrounded by a parenchymatous sheath. (E) Myrceugenia euosma, showing adaxial hypodermis of one layer of cells with thickened periclinal walls, abaxial papillose cells and secretory trichomes; palisade parenchyma occupies 50–60% of the mesophyll and spongy parenchyma has many intercellular spaces. Scale bars = 30 mm (A–E). three subtribes, the pericyclic cells form a continuous layer around the vascular bundle (Figs 4A, C, E, 5A, D, 6B–D, Tables 4, 5), whereas in others, the vascular bundle is surrounded by sparsely distributed fibres (Figs 4B, D, F, 5B, C, 6A, Tables 4, 5), or concentrated in the adaxial part of the arc, as observed in some Myrciinae and Eugeniinae. An angular collenchyma adjacent to the two foliar surfaces (Figs 4A–F, 5A–D, 6A–D), some secretory cavities close to the epidermis and to the vein, and crystals and idioblasts containing druses (Figs 4A, C, E, F, 5B, D, 6A, C, D) are frequent in the midrib in all subtribes. Discussion All the leaves studied are dorsiventral, hypostomatic and present stomata slightly protruding in relation to the epidermis. Hypostomatic and dorsiventral leaves are common in most representatives of the order Myrtales (Keating 1984), except Foliar anatomy of Myrtoideae Australian Journal of Botany 155 (A) (B) (C) (D) Fig. 3. Eugeniinae leaves in cross-section. (A) Myrciaria tenella, showing palisade parenchyma occupying 25% of the mesophyll and compact spongy parenchyma; vascular bundle surrounded by a parenchymatous sheath. (B) Plinia rivularis, mesophyll with 50% of palisade parenchyma and compact spongy parenchyma; note the presence of crystals. (C) Siphoneugena densiflora, showing palisade parenchyma occupying 20% of the mesophyll and compact spongy parenchyma; vascular bundle is surrounded by a parenchymatous sheath. (D) Hexachlamys itatiaiensis, epidermal cells of the adaxial surface with inner periclinal walls thickened and palisade parenchyma occupying 30–40% of the mesophyll. Scale bars = 20 mm (A, B) and 30 mm (C, D). for certain Melastomataceae (Reis et al. 2005) and Combretaceae (Tilney 2002), which have amphistomatic and isobilateral leaves. As observed for most of the leaves, the presence of a thick cuticular layer and of epidermal cells more developed on the adaxial than on abaxial surface is common within Myrtales, as described also by Keating (1984) for some Lythraceae, Rynchocalycaceae, Melastomataceae, Crypteroniaceae, Psiloxylaceae, Myrtaceae, Onagraceae and Combretaceae (Tilney 2002), and by Sajo and Rudall (2002) for Vochysiaceae. In some representatives of Vochysiaceae, the adaxial epidermis is two- or more-layered (Sajo and Rudall 2002) and, although this family is closely related to Myrtaceae (Conti et al. 1996, 1997; Wilson et al. 2001), no one leaf examined here presented a multilayered epidermis. Solereder (1908) reported the occurrence of a papillose differentiation of the abaxial epidermal surface of Melaleuca hypericifolia (subfamily Leptospermoideae) leaf. According to Metcalfe and Chalk (1979), the papilla is the simplest kind of trichome, being formed by one cell with a short projected outer periclinal wall. As observed here, the leaves of Myrceugenia euosma (subfamily Myrtoideae, subtribe Myrciinae) are abaxially covered by papillae, as also described for other Myrtaceae (Metcalfe and Chalk 1979) and for Gomidesia nitida, which belongs to the same subtribe as Myrceugenia (Gomes and Neves 1997). The presence of a hypodermis, as observed here for Myrceugenia euosma (subtribe Myrciinae), Campomanesia, Pimenta and Psidium (subtribe Myrtinae) and for Myrcianthes (subtribe Eugeniinae) was also reported for other Psidium by Solereder (1908), Metcalfe and Chalk (1950), Backes (1971), Arruda and Fontenelle (1994) and Boeger and Wisniewski (2003) and for Gomidesia fenzliana (subtribe Myrciinae) by Fontenelle et al. (1993). Hypodermis is a common tissue within Myrtales, occurring in some Alzateaceae, Combretaceae, Melastomataceae, Myrtaceae, Oleaceae, Rynchocalycaceae (Keating 1984) and Vochysiaceae (Sajo and Rudall 2002). According to Fahn (1990), this subepidermal tissue, which originates from both the protoderm and the fundamental meristem, is related with water storage and is formed by enlarged cells with thin walls in succulent plants, and by small cells with thickened walls in coriaceous leaves. Feller (1996) considered the hypodermis as a protection of the photosynthetic 156 Australian Journal of Botany C. M. V. Cardoso et al. (A) (C) (B) (D) (E ) (F ) Fig. 4. Cross-sections of the midrib of Myrtinae. (A) Campomanesia sp., with flattened adaxial surface and a vascular system forming an arc of xylem, surrounded abaxially by phloem and adaxially by phloem interspersed with xylem. (B) Psidium guineense, with flattened adaxial surface and vascular system forming an arc with opened extremities, and without phloem confluence. (C) Blepharocalyx salicifolius, with flattened adaxial surface, and a vascular system with the extremities curved inward, forming two islands of xylem surrounded by phloem adaxially. (D) Campomanesia guazumifolia, showing convex adaxial surface and a vascular system forming an arc with open extremities, and without phloem confluence. (E) Pimenta pseudocaryophyllus, with convex adaxial surface, and a vascular system in the form of an arc with open extremities, surrounded completely by sclerified pericyclic cells. (F) Mosiera prismatica, showing adaxial surface in the form of an acute projection and a vascular system in the form of an arc, with the extremities curved inward, forming two islands of xylem surrounded by phloem adaxially; note phloem confluence. Scale bars = 30 mm (B), 70 mm (A, C, D, F) and 200 mm (E). leaf tissue, and related its occurrence to a low metabolic rate caused by both mineral deficiency and by light excess. This hypothesis may explain why some species of Myrtinae collected in the cerrado habitats (see Table 2), where high luminosity predominates and the soils are poor in minerals, presented a hypodermis. The only Myrciinae with a hypodermis is Foliar anatomy of Myrtoideae Australian Journal of Botany (A) (B) (C) (D) 157 Fig. 5. Cross-sections of the midrib of Myrciinae. (A) Myrcia laruotteana, with flattened adaxial surface and a vascular system in the form of an arc, with the extremities curved inward, forming two islands of xylem surrounded by phloem adaxially. (B) Gomidesia spectabilis, showing flattened adaxial surface and a vascular system in the form of an arc of xylem, surrounded abaxially by phloem and adaxially by phloem interspersed with xylem; note a central medulla in the vascular bundle. (C) Myrceugenia hatsbachii, with grooved adaxial surface and a vascular system is the form of an arc with open extremities, without phloem confluence; abaxial phloem is more developed than the adaxial one. (D) Myrcia tomentosa, with convex adaxial surface and a vascular system in the form of an arc, with the extremities curved inward, forming two islands of xylem surrounded by phloem adaxially. Scale bars = 70 mm (A–D). Myrceugenia euosma which, although considered by Landrum (1981) the most xerophytic species of the genus, grows in flooded areas, such as swamps and floodplains (Soares-Silva 2000). Metcalfe and Chalk (1950) reported isobilateral leaves for most Myrtaceae they studied and also referred to the occurrence of dorsiventral leaves in Eugenia and Eucalyptus. In contrast, the leaves of the Myrtaceae studied by Keating (1984) where dorsiventral, as in all the species observed here. With regard to the other Myrtales, dorsiventral mesophyll seems to be characteristic of most species (Keating 1984; Sajo and Rudall 2002), although some Combretaceae (Keating 1984; Tilney 2002), Lythraceae, Melastomataceae (only Mouriri), Memecylaceae and Onagraceae (Keating 1984; Tilney 2002) have isobilateral leaves. The leaves studied here commonly contain druses and single rhombohedral, prismatic crystals. Such crystals, especially the druses, are also common in the Myrtales (Solereder 1908; Metcalfe and Chalk 1950; Keating 1984; Sajo and Rudall 2002; Tilney 2002). Phenolic compounds, as observed in the mesophyll of most Myrtinae, are not rare in the order, appearing in Vochysiaceae (Sajo and Rudall 2002), Combretaceae (Tilney 2002) and Melastomataceae (Reis et al. 2005). Lucas (1971) mentioned sclereids in the mesophyll of the Myrtaceae Jambosa vulgaris, whereas Carr and Carr (1971) reported the presence of fibres in the mesophyll of Angophora and Eucalyptus (Myrtaceae). Sajo and Rudall (2002) found sclereids in the mesophyll of some Vochysiaceae and Reis et al. (2005) in some Melastomataceae. However, all the leaves studied in the present work lack sclereids and fibres in the mesophyll, confirming the observations of Keating (1984) for Myrtales, in general. Most leaves have the adaxial surface flattened in the midrib region, although a grooved surface occurs in some species of the three subtribes (Table 4), as also described by Ferri (1971) for Psidium guayava and P. multiflorum, by Arruda and Fontenelle (1994) for Marlierea suaveolens, by Callado (1997) for Eugenia cuprea and by Keating (1984) for Syzygium paniculatum. In Mosiera (subtribe Myrtinae), the adaxial surface presents a projection and, in certain species, the adaxial surface has a convex form (Table 4). A collenchyma adjacent to one or both 158 Australian Journal of Botany C. M. V. Cardoso et al. (A) (B) (C) (D) Fig. 6. Cross-sections of the midrib of Eugeniinae. (A) Hexachlamys itatiaiensis, showing flattened adaxial surface and a vascular system in the form of an arc of xylem, surrounded abaxially by phloem and adaxially by phloem interspersed with xylem. (B) Myrciaria cuspidata, with grooved adaxial surface and a vascular system in the form of an arc with open extremities, and without phloem confluence; abaxial phloem is more developed than the adaxial one. (C) Eugenia aurata, showing convex adaxial surface and a vascular system in the form of an arc with open extremities, and without phloem confluence; abaxial phloem is more developed than the adaxial one. (D) Siphoneugena densiflora, with convex adaxial surface and a vascular system formed by a ring of xylem, surrounded externally by phloem and internally by phloem interspersed with xylem. Scale bars = 30 mm (B) and 70 mm (A, C, D). surfaces is frequent in the midrib region of the studied leaves, as reported for other Myrtaceae (Backes 1971; Lucas 1971; Callado 1997; Gomes and Neves 1997). Within Myrtales, the vascular system of the midrib consists of xylem surrounded adaxially and abaxially by phloem. According to Keating (1984), the shape of the vascular system relates to the size of the foliar veins. Therefore, arched, rounded or flattened bundles characterise small veins, whereas semicircular or circular bundles characterise the prominent ones. The leaves studied here have a vascular system in the form of an open or curved arc, except for Siphoneugena which has a cylindrical vascular system. Even so, the veins are prominent in Acca, Campomanesia, Pimenta and in most Psidium, of the subtribe Myrtinae, in all the species of Myrciinae (except for Myrcia bella and Myrcia torta) as well as in Eugenia, Hexachlamys, Myrcianthes, Myrciaria delicatula, Neomitranthes, Plinia trunciflora and Siphoneugena, of the subtribe Eugeniinae. The vascular system occupies the same level as the mesophyll in most Myrtinae and Myrciinae, and in all specimens of Eugeniinae (see Tables 4, 5). In the other species, it is abaxially prominent (Table 4). The vascular bundles of minor caliber are collateral and surrounded by a parenchymatous sheath that may or may not present extensions towards the leaf surfaces. Within Myrtales, bundle sheaths with extensions are reported for Lythraceae, Trapaceae, Combretaceae, Myrtaceae (Keating 1984), Vochysiaceae (Sajo and Rudall 2002) and Melastomataceae (Reis et al. 2005). As previously described for the family (Metcalfe and Chalk 1950; Dahlgren and Thorne 1984; Keating 1984), dorsiventral and hypostomatic leaves bearing secretory cavities and vascular bundles, with phloem in the adaxial and abaxial positions, characterise all the species of Myrtinae, Myrciinae, and Eugeniinae. In addition, other features, such as those reported in Tables 2–5, were shown to have diagnostic value for the genera of the three subtribes. Foliar anatomy of Myrtoideae Australian Journal of Botany 159 Table 5. Features observed in the midrib region of Myrciinae leaves AB = abaxial, AD = adaxial Species Subtribe Myrciinae Calyptranthes concinna C. widgreniana Gomidesia fenzlianaA G. lindeniana G. martianaA G. nítidaB G. spectabilis Marlierea eugeniopsoides M. obscura M. suaveolensC Myrceugenia euosma M. hatschbachii M. ovata Myrcia bella M. laruotteana M. lingua M. rostrata M. tomentosa M. torta A Collection site Woods Cerrado Restinga Cerrado Restinga Restinga Woods Woods Woods Woods Várzea Várzea Campo Cerrado Cerrado Cerrado Cerrado Cerrado Cerrado Adaxial surface Arc Position Grooved Grooved Flat Flat Flat Flat Flat Flat Flat Grooved Grooved Flat Grooved Flat Flat Convex Flat Convex Flat Open Open Open Open Open Open Open Open Curved Open Curved Open Open Open Curved Open Open Curved Open Level Level Level Dislocated Dislocated Dislocated Dislocated Dislocated Level Level Level Level Level Level Level Level Level Dislocated Level Vascular System Phloem Confluence Proportion No No Yes No No Yes Yes No Yes No Yes No No No No Yes Yes No Yes AD > AB AD > AB AD > AB AD > AB AD < AB AD > AB AD > AB AD > AB AD > AB AD < AB AD < AB AD < AB AD < AB AD < AB AD > AB AD > AB AD > AB AD > AB AD < AB Sclerenchymatic sheath Discontinuous (AD) Continuous Continuous Continuous Continuous Continuous Discontinuous (AD) Continuous Continuous Continuous Continuous Discontinuous (AB) Continuous Continuous Continuous Continuous Continuous Continuous Continuous Fontenelle et al. (1993); BGomes and Neves (1997); CCallado (1997). Subtribe Myrtinae (Tables 2, 5) The genus Acca is distinguishable in having a leading leaf with four or five layers of palisade parenchyma and trichomes on the abaxial surface. Trichomes on this surface occur also in the genus Pimenta, although here the palisade parenchyma occupies half of the mesophyll whereas in Acca it occupies 25–30%. Contrary to Acca, the Pimenta leaves have a hypodermis and a vascular bundle sheath with prominent extensions that compartmentalise the mesophyll. At the midrib region, the adaxial surface of the leaf is convex in Pimenta and grooved in Acca. The phloem is not confluent in Acca, whereas in Pimenta and Myrrhinium, the phloem in the midrib region is confluent. However, in Myrrhinium, the adaxial and abaxial phloem are equivalent (in Pimenta the adaxial is more developed), the palisade parenchyma occupies 20% of the mesophyll (50% in Pimenta) and there is no hypodermis nor sheath extension on the vascular bundles (which exist in Pimenta). Reduced palisade parenchyma, epidermis without trichomes and midrib level with the lamina characterise the leaves of Accara, Blepharocalyx, Calycolpus and Mosiera. However, in Accara, the vascular system of the midrib is in the form of an open arc, whereas in Blepharocalyx, Calycolpus and Mosiera it is a curved arc. Blepharocalyx differs from Calycolpus in having adaxial epidermal cells with thickened periclinal walls (in Calycolpus only the outer periclinal wall is thickened), spongy parenchyma with loosely packed cells (compactly arranged in Calycolpus) and the same proportion of adaxial and abaxial phloem in the midrib (in Calycolpus the adaxial is more developed). The leaves of Mosiera are distinguishable by the occurrence of a prominent convex adaxial midrib (flattened in Accara and Blepharocalyx and grooved in Calycolpus) and a discontinuous sheath of sclerified cells around the vascular system (continuous sheath in Accara, Blepharocalyx and Calycolpus). In Campomanesia, the leaf bears trichomes on both surfaces, the palisade tissue occupies 50% of the mesophyll, and the vascular bundle sheath shows extensions towards both surfaces. In species of Campomanesia with a hypodermis, the sheath extensions compartmentalise the mesophyll, as observed in Pimenta leaves. In Campomanesia, the midrib is strongly abaxial (in Pimenta it is level with the lamina prominent), the adaxial and abaxial phloem of the midrib do not fuse at the extremities of the arc (confluent in Pimenta) and the adaxial midrib is flattened (convex in Pimenta). In most of Psidium, the leaves have an adaxial hypodermis, mesophyll compactly arranged and trichomes on both surfaces. The vascular system of the midrib is in the form of an open arc and projects in relation to the lamina. The percentage of palisade tissue varies among species (25–50%) and, although Ferri (1971) and Souza (1971) described the mesophyll of Psidium guayava as completely composed of palisade parenchyma, their illustrations do not make it clear whether the abaxial cells constitute palisade or not. In the midrib, Psidium leaves vary in the shape of the adaxial surface, in the proportion and confluence between the adaxial and abaxial phloem and in the shape of the vascular bundle sheath. Such variability is probably related to the diversity of the genus that comprises ~70 species growing in different habitats, such as woodlands, cerrado and restinga. Subtribe Myrciinae (Table 3) The leaves of Myrcia and Myrceugenia are distinct from those of the other genera in having a more developed palisade tissue (40–60% of the mesophyll, see Table 3). In Myrceugenia, this 160 Australian Journal of Botany tissue is multilayered whereas in most Myrcia it is one- or twolayered. In addition, the cells of the spongy parenchyma are loosely packed in Myrceugenia whereas they are compactly or loosely arranged in Myrcia, depending on the species. In the midrib, the vascular bundle sheath of Myrceugenia may or may not be continuous, although all species have abaxial phloem more developed than the adaxial one. In contrast, the vascular bundle sheath of Myrcia is always continuous and most species have the adaxial phloem more developed than the abaxial one. Furthermore, in Myrceugenia leaves, there are big substomatal chambers shared by more than one stoma (absent in Myrcia); in Myrceugenia euosma the chambers occur an adaxial hypodermis (not observed in Myrcia) and secretory trichomes on the abaxial surface (absent in Myrcia). The leaves of Marlierea have a one-layered palisade parenchyma, occupying 20–30% of the mesophyll, and a spongy parenchyma of lobed cells loosely packed. In the midrib, the vascular system has a continuous sheath of sclerified cells and the adaxial phloem is more developed than the abaxial one. In Calyptranthes and Gomidesi, palisade parenchyma occupies 25–30% of the mesophyll. The leaves of Calyptranthes are glabrous (hairy in Gomidesia), the cells of the spongy parenchyma are compactly arranged (loosely arranged in Gomidesia), the adaxial surface is grooved in the midrib region (flattened in Gomidesia) and the midrib vascular system is protuding (level in Gomidesia). Subtribe Eugeniinae (Table 4) The leaves of Myrcianthes are unique in having an adaxial hypodermis formed by cells leading with thickened periclinal walls (absent in the other genera) and only Siphoneugena has leaves with the vascular system of the midrib in the form of a ring (open or curved arc in the other species). In the leaves of Calycorectes, the palisade parenchyma occupies 20–30% of the mesophyll and the spongy parenchyma cells are lobed. The vascular system of the midrib has the form of two islands of xylem surrounded by phloem or of an open arc, with adaxial phloem more developed than the abaxial one and interspersed with xylem cells, as also observed for Hexachlamys (Eugeniinae). However, in Hexachlamys, the palisade tissue occupies 30–40% of the mesophyll, the spongy parenchyma cells are compactly arranged (loosely in Calycorectes) and the vascular bundle sheaths have extensions (absent in Calycorectes). Furthermore, the leaves of Hexachlamys are hairy and its adaxial epidermal cells have inner periclinal walls thickened. In contrast, those of Calycorectes are glabrous and its adaxial epidermal cells have only the outer periclinal walls thickened. As in Calycorectes, the Neomitranthes leaves have poorly developed palisade parenchyma (20% of the mesophyll). However, in Neomitranthes, the vascular system of the midrib has the form of an arc with curved ends (open arc in Calycorectes), the epidermal cells of both surfaces are of the same size (cells of the adaxial surface bigger in Calycorectes) and the cells of the spongy parenchyma are compactly arranged (loosely packed in Calycorectes). In Plinia the epidermal cells of the adaxial surface have the outer periclinal walls thickened and mesophyll with 30–50% of the palisade parenchyma plus a spongy parenchyma of compactly C. M. V. Cardoso et al. arranged cells. The vascular system of the midrib is in the form of an open arc, with the adaxial phloem more developed than the abaxial one. The genera Myrciaria and Eugenia comprise many species and present a large variability in leaf structure. However, mesophyll with 25–30% of palisade parenchyma and a vascular system of the midrib forming an open arc prevail in these two genera. In most Eugenia, the adaxial epidermal cells are bigger than the abaxial ones, the cells of the spongy parenchyma are loosely arranged, the adaxial phloem of the midrib is more developed than the abaxial one, and they may or may not be joined. In most Myrciaria leaves, the adaxial epidermal cells are bigger than the abaxial ones, the cells of the spongy parenchyma are compactly arranged and the vascular system of the midrib is in the form of an open arc. The proportion between the adaxial and abaxial phloem of the midrib varies according to the species and there is no confluence of the phloem in this region. Conclusion The results obtained in the present work show that all the morphoanatomical features analysed, including the percentage of palisade parenchyma, the presence or not of adaxial hypodermis, the occurrence or not of parenchymatous or sclerenchymatous sheath extension in the vascular bundles, as well as the shape and location of the vascular system in the central vein, have no diagnostic value in distinguishing among the three subtribes studied. Nevertheless, although such features cannot be used on their own to separate taxa, combined with other morphological characteristics they may contribute to distinguishing among the taxa. Because the leaf morphoanatomy of the Brazilian species of Myrtaceae is still relatively poorly known, recognition of the anatomical characters analysed in the present study is an important contribution to the knowledge on these species and on this family as a whole. Acknowledgements We thank CAPES (Comissão de Aperfeiçoamento de Pessoal de Nível Superior, Brasil) for the doctoral fellowship (for C. M. V. Cardoso) and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brasil) for the Researcher fellowship (for M. G. Sajo). We also thank Projeto Biota – FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) for financial support. References Arruda RCO, Fontenelle GB (1994) Anatomia foliar de Psidium cattleyanun. Revista Brasileira de Botânica 17, 25–35. Backes A (1971) Contribuição ao estudo da anatomia foliar e da fisiologia de Psidium multiflorum Camb. Ciencia e Cultura 23, 297–303. Behar L (1971) Dados sobre transpiração e anatomia foliar de Eugenia uniflora L. Ciencia e Cultura 23, 273–284. Berg OC (1855) Revisio Myrtacearum Americae. Linnaea 27, 1–472. Berg OC (1857) Myrtaceae. In ‘Flora Brasiliensis’. Vol. 14. pp. 1–655. 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