HIGGINS ET AL.: ENCYCUA 179

coding regions of chloroplast DNA. PI. Mol. Bio. Subtribal and generic relationships of Maxillarieae 17: 1105-1109. (Orchidaceae) with emphasis on Stanhopeinae: The Names Project. 1999. International Plant combined molecular evidence. Am. J. Bot. 87: Names Index. Published on the Internet; http:// 1842-1856. www.ipni.org [accessed 31 July 2003]. Williams, N.H., M.W Chase, T. Fulcher and W.M. Thollesson, M. 2000. Increasing fidelity in parsimony Whitten. 2001. Molecular systematics of the On­ analysis of dorid nudibranchs by differential cidiinae based on evidence from four DNA se­ weighting, or a tale of two genes. Mol. Phyl. Evol. quence regions: expanded circumscriptions of Cyrtochilum, Erycina, Otoglossum, and Tricho­ 16: 161-172. centrum and a new genus (Orchidaceae). Lindley­ van den Berg, C., W.E. Higgins, R.L. Dressler, W.M. ana 16: 113-139. Whitten, M.A.S. Arenas, A. Culham and M.W. Withner, C.L. 1988. The Cattieyas: The Cattleyas and Chase. 2000. A phylogenetic analysis of Laeliinae their Relatives. Timber Press, Portland, Oregon. (Orchidaceae) based on sequence data from inter­ ---. 1998. Brassavola, Encyclia, and Other Genera nal transcribed spacers (ITS) of nuclear ribosomal of Mexico and Central America: The Cattleyas DNA. Lindleyana 15: 96-114. and their Relatives. Timber Press, Portland, Whitten, WM., N.H. Williams and M.W Chase. 2000. Oregon. Selbyana 24(2): 180-189.2003.

FOLIAR ANATOMY OF FIVE VR/ESEA SECT. X/PH/ON ()

ROSANI DO CARMO DE OLNEIRA ARRUDA Departamento de Ciencias Naturais, Escola de Ciencias Biol6gicas, Universidade do Rio de Janeiro, Avenida Pasteur, 458, Urca, Rio de Janeiro, 22030-240, RJ, Brasil. E-mail: [email protected]

ANDREA FERREIRA DA COSTA* Departamento de Botfurica, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, Sao Crist6vao, 20940-040 Rio de Janeiro, RJ, Brasil. E-mail: [email protected]

ABSTRACT. The present work aims to extend the knowledge of the genus Lindley, contributing data on the foliar anatomy of five species: Vriesea bituminosa Wawra, V. longiscapa Ule, V. triligulata Mez, V. gigantea Gaudich., and V. Josteriana L.B.Sm. Transverse and longitudinal cuts were made manually in fully expanded leaves. The usual histochemical tests were performed. Features typical to the Bromeli­ aceae were peltate trichomes, single layered epidermis, stomata located only on the abaxial surface of the leaves, a hypodermis with mechanical and water-storing functions, and collateral vascular bundles. Ob­ served differences among the species were number of trichomes in both lamina and sheath, number of cells on the trichome shield, and number of layers of the aquiferous hypodermis. Many of the observed char­ acteristics confirm the xerophytic nature of the leaves. The anatomical organization of the leaves in the studied Bromeliaceae could be related both to environmental pressures as well as to phylogenetic relation­ ships.

RESUMO. 0 presente trabalho tern como objetivo ampliar 0 conhecimento acerca do genero Vriesea Lind­ ley fornecendo dados sobre a anatomia foliar de cinco especies: Vriesea bituminosa Wawra, V. longiscapa Ule, V. triligulata Mez, V. gigantea Gaudich. e V. Josteriana L.B.Sm. 0 material botanico foi cortado a mao livre. Testes histoquimicos usuais foram realizados. Os resultados mostraram que as especies exibem as caracteristicas tipicas da farm1ia: folhas hipoestomaticas, epiderme simples dotada de tricomas peltados multicelulares, hipoderme com funl(oes meciinica e de reserva de agua, tecido clorofiliano diferenciado em palil(adico e esponjoso do tipo braciforme e feixes vasculares colaterais. Foram notadas diferenl(as entre as especies com relal(ao a quanti dade de tricomas ao longo da folha; mimero de celulas que compoem 0 escudo dos tricomas e mimero de camadas da hipoderme aquffera. As caracteristicas observadas confirmam a natureza xerofftica das folhas. A organizal(ao anatomica das folhas das Bromeliaceae estudadas pode ser uma resposta a press5es ambientais assim como refietir relal(oes filogeneticas.

Key words: Bromeliaceae, Vriesea, leaf anatomy, epiphytes

INTRODUCTION Although some anatomic studies have been conducted (Tomlinson 1969, Benzing 1970, Comprising nearly 2700 species (Benzing 1976, Braga 1977, Souza & Neves 1996, Sajo 2000) in 56 genera (Grant & Zijlstra 1998), the et al. 1998), the existing data on particular Bromeliaceae family presently represents an ex­ tremely diversified group of vascular , groups are fragmented and little explored, as for which has colonized a variety of neotropical example the genus Vriesea Lindl. Considering habitats (Dahlgren et al. 1985). Specialization the present infra-generic division of Vriesea, the related to water-storage, represented by sheath Section Xiphion comprises ca. 130 species (Lu­ development as well as xeromorphic leaf struc­ ther & Sieff 1994, 1997a, 1997b, Luther 2001). ture in many species, is a remarkable feature of These species are characterized predominantly this family, not yet sufficiently investigated. by an inflorescence with dull colors; corolla with Family representatives are found both in xeric cream, yellow, or reddish petals; androecium and mesic environments, from sea level to and gynoecium included within the corolla; and mountaintops, and account for a considerable stigma with the convolute-blade type morphol­ portion of the epiphytic vegetation in neotropical ogy (Grant 1993, 1995a, 1995b). forests (Benzing 1990). The present work provides data on the foliar anatomy of five species of the Xiphion section * Corresponding author. of Vriesea, which are discussed in the light of 180 ARRUDA & COSTA: VRIESEA FOLIAR ANATOMY 181

possible plant-environment relationships and as view (adaxial and abaxial surfaces) and trans­ a contribution to the systematics of the family. verse section (FIGURES 1, 2; TABLES 1-3).

MATERIAL AND METHODS Face view at median third level The following species were examined: Vrie­ The epidermis, seen in a face view of the ad­ sea bituminosa Wawra, V. longiscapa Ule, V. axial surface at the median third level, is com­ triligulata Mez, V. gigantea Gaudich., and V. posed of trichomes and common epidermal cells Josteriana L.B.Sm. Plant material for the first disposed parallel to the longest axis of the lam­ three species was collected at Serra de Macae ina (FIGURE 1A). The common epidermal cells, de Cima (Costa 1993), and exsiccates are de­ rectangular with rather sinuous and thickened posited at the Rio de Janeiro Botanical Garden anticlinal walls, show a siliceous body (FIGURE Herbarium (RB). For the fourth species, material IF). The trichomes are distributed randomly was collected by T. Strehl, in January 1994, at along the epidermal tissue (FIGURE lA, B). His­ Santo Antonio da Patrulha Municipality, Rio tochemical tests show the presence of phenolic Grande do SuI; and exsiccates are deposited at substances in such cells, the reaction being more Herbarium Alarich Schulz (HAS); and finally V. evident in cells from the central disk. TABLE 1 Josteriana material comes from Espfrito Santo presents the average proportion of trichome dis­ State and is deposited at Museu Nacional Her­ tribution over this leaf region. barium (R). On the abaxial surface, the epidermis presents All species are typical tank-bromeliads with organization in costal and intercostal bands of epiphytic habit, except Vriesea Josteriana, ordinary epidermal cells. The presence of sili­ which is rupicolous. Fully expanded leaves ceous bodies can be observed (FIGURE 1B); the (lamina and sheath) were preserved in ethanol stoIllata are of the tetracytic type with kidney­ 70° GL (Jensen 1962). Transverse and longitu­ shaped guard cells, and they are arranged in two dinal sections were then prepared by hand. Sec­ or four ranks (TABLE 2). Around the stomatal tions were stained with a mixture of safranine complex, the epidermal cells show straight, and Astra blue (Kraus & Arduin 1997). Epider­ thickened walls, the contents of which present mal analyses were carried out on material dis­ similar histochemical reactions to those from sociated by immersion in Schultze's mixture subsidiary cells. The stomata may occur either (Sass 1951). Paradermic sections were then isolated or in groups of two to five, among stained with aqueous safranine (Johansen 1940). which the trichomes are located. Trichomes ap­ Stomata were classified according to Metcalfe (1963). Numbers of stomata and trichomes were pear restricted to intercostal bands (FIGURE 1B) in an average that varies from 13.8 (Vriesea gi­ recorded as the mean obtained from 20 I-mm2 fields. The number of cells composing the wing gantea and V. longiscapa) to 20.9 (V. trigulata) corresponds to the mean of counting 15 intact (TABLE 1). scales. Sections of non-fixed material were used for the following histochemical tests: Sudan IV Face view at sheath level (Jensen 1962) for cutinized walls and drops of In face view of the epidermis at sheath level, oil, chlorzinc iodine (Strasburger 1924) for cel­ features generally are similar to those described, lulosic walls; phloroglucinol (Foster 1949) for except for a remarkable absence of stomata on lignified walls; iodine in potassium iodide (Jo­ either side of the leaf and the presence of tri­ hansen 1940) for starch; iron sulfate solution chomes that show rather different morphological (Johansen 1940) for phenolic compounds, and features from those of the median third (FIGURE clove oiVphenol (Netolitzki 1935) for siliceous 2A-E). In this region, the scales average a larger structures. number of wing cells compared to the median third (TABLE 3). In both regions, the scales have RESULTS only one ring of eight cells. The wing cells have In studying the leaf anatomy of Vriesea spe­ elongated forms with unevenly thickened radial cies, we focused on the structure of plant cells walls in the portion facing the cell interior, in the epidermis and mesophyll. Resulting de­ granting varied forms to the lumen, especially in scriptive data follows. Vriesea gigantea and V. triligulata (FIGURE 2B, C). These scales are randomly distributed. The common epidermal cells, with strongly thick­ Epidermis ened and sinuous anticlinal walls, contain a si­ The structure of the epidermis on the median liceous spherical body at a rate of one per cell, third and sheath levels was examined in face rarely two. 182 SELBYANA Volume 24(2) 2003

FIGURE 1. Foliar epidermis of Vriesea (Xiphion) species in face view and transverse section (bar = 25 J.Lm). A. V. longiscapa, adaxial surface, trichome shield (arrow). B. V. josteriana, abaxial surface, stomatal complex (SC), trichome shield (*), ordinary epidermal cells with silica bodies (arrows). C. V. triligulata, adaxial surface, inner periclinal wall (W). D. V. josteriana: stomatal cell (ST), subsidiary cell (SU). E. V. bituminosa, trichome stalk cells (STC). F. V. josteriana, trichome stalk cells (STC) and silica body (SI).

Transverse section at median third periclinal walls are thin, whereas the inner ones and sheath levels are strongly thickened, as in V. triligulata (FIG­ The epidermis, in a transverse section of the URE Ie), and weakly lignified. Because of the lamina at the median third level, is shown to be evident wall thickening, the epidermal cells single layered (FIGURE 3B) and covered by a cu­ show reduced lumen, which tend to different ticle layer that ranges from thin in Vriesea lon­ shapes in the species studied (TABLE 2). Similar giscapa to very thick in the others. The outer characteristics can be observed at the sheath lev- ARRUDA & COSTA: VRIESEA FOLIAR ANATOMY 183

A 8

I

c o

E

FIGURE 2. Drawings showing trichome shields of sheath leaf of Vriesea (Xiphion) species. A. V. longiscapa. B. V. triligulata. C. V. gigantea. D. V. fosteriana. E. V. bituminosa (bar = 25 fLm). el, except, however, for the presence of a very cells, with a group of five to seven cells sup­ thin cuticular layer. porting the shield and constituting the foot of the The scales on both sides of the leaf, in the trichome (FIGURE IE, F). The transverse section median third and sheath regions, are inserted at shows that the periclinal walls of the shield cells an inferior level to that of the other epidermal present thickened primary walls, especially 184 SELBYANA Volume 24(2) 2003

TABLE 1. Average number of trichomes and stomata (mm2) from the leaf median third and sheath level of Vriesea (Xiphion) species.

Trichomes Trichomes sheath level median third level Stomata Vriesea species Adaxial surf. Abaxial sutf. Adaxial surf. Abaxial surf. median third level V. bituminosa 4.5 13.9 41.2 V. Josteriana 10.2 15.4 16.72 12.04 42.1 V. gigantea 7.7 13.8 19.73 15.3 46.4 V. longiscapa 7.4 13.8 9.56 8.12 25.7 V. triligulata 10.3 20.9 17.24 13.28 38.0

those of the central disk, the lumen of which is ened as in Vriesea Josteriana (FIGURE 3A) and restricted to a narrow slot. Under the shield, the V. triligulata (FIGURE 3C) and thinner in V. gi­ dome cell has a roughly triangular section, while gantea, V. bituminosa (FIGUrtE 3B) and V. lon­ other cells have rectangular sections. Thin pri­ giscapa. Under this stratum, tlrree to seven lay­ mary cell walls generate a strong reaction for ers of non-chlorophyllous cells with relatively the presence of lipid substances. thin walls constitute a water-storing tissue (TA­ Stomata, covered by cuticle that invades part BLE 4). Among these cells are groups of lignified of the substomatal chamber, may occur at the fibers (FIGURE Ie), consisting of a varied num­ same level of other epidermal cells (Vriesea tri­ ber of elements remarkably developed in por­ ligulata, V. longiscapa, V. Josteriana), slightly tions related to large-sized vascular bundles above them (V. bituminosa), or below them (V. (FIGURE 3B). The chlorophyllous parenchyma, gigantea) (TABLE 2). The stomatal cells have re­ with extremely thin-walled cells, occupies the duced lumen with strongly thickened periclinal median-lower region of the mesophyll and is walls (FIGURE 1D). The surrounding sub-epider­ differentiated into palisade parenchyma and mal cells of the stomatal complex send out pro­ spongy parenchyma with stellate cells (FIGURE jections towards the pore and partially obliterate 3A, B, TABLE 4). This organization is loosely the stomatal opening. These projections have differentiated in V. longiscapa and very clear in primary walls. the other species. Idioblasts containing raphides are observed in the spongy parenchyma of V. Mesophyll gigantea. In the portion turned to the abaxial surface of the lamina, the stellate parenchyma The structure of the mesophyll, including the cells touch the substomatal chambers (FIGURE vascular system, was examined in transverse 3B). section at median third and sheath levels (FIGURE 3, TABLE 4). Sheath level In the sheath, subjacent to the abaxial face of Median third level the epidermis, occurs a layer (simple in Vriesea The mesophyll shows a tendency to the dor­ longiscapa and double in the other species) of siventral structure (FIGURE 3A, B). Below the narrow-lumen cells with extremely thickened epidermis there is a hypodermis with a differ­ walls and numerous simple pits. These cells entiated mechanical portion whose cell walls show a strong reaction to phenolic substances, (two or three layers) may appear strongly thick- and negative reaction to lignin. The subepider-

TABLE 2. Other epidermic cells features distinguishing the five Vriesea (Xiphion) species studied.

Lumen shape in Stomatal cell position in Subepid. cell No. stomata ranks common epid. cells common epidermal cells section shape Vriesea species FV, MTL TS, MTL TS, MTL M, SL V. bituminosa 4 pentagonal slightly above epid. cells circular V. Josteriana 2 rectangular same level elongated V. gigantea 4 pentagonal above epid. cells elongated V. longiscapa 2 rectangular same level thickened V. triligulata 2 triangular same level circular Note: FV = face view. TS = transverse section. M = mesophyll. MTL = median third level. SL = sheath level. ARRUDA & COSTA: VRIESEA FOLIAR ANATOMY 185

TABLE 3. Average number of cells that integrate the The sinuosity of the ordinary anticlinal cell trichome shield wings of Vriesea (Xiphion) spe­ walls of the epidermis observed in the study spe­ cies. cies is a common feature of many bromeliad species in all three subfamilies (Tomlinson Median third level Sheath level 1969). Sinuosity may protect internal tissues, Adaxial Abaxial Adaxial Abaxial maintaining leaf structure during periods of Vriesea species surf. surf. surf. surf. change in water availability, winds, and rain V. bituminosa 30.0 32.3 40.5 55.6 (Haberlandt 1928, Krauss 1949). Spherical silica V. Josteriana 40.6 46.0 51.7 52.6 bodies are common in Bromeliaceae species V. gigantea 45.0 62.2 56.8 (Tomlinson 1969). V. longiscapa 32.0 32.0 37.3 42.7 In many species of the family, stomata show V. triligulata 30.0 32.3 34.6 54.7 modifications related strictly to their water bud­ get. They are generally restricted to the abaxial surface of the leaves and located at the same mal cell sections have different shapes (TABLE level, or in depressions of different depths in 2). The subepidermal tissue makes this leaf re­ relation to the epidermis (Tomlinson 1969, Sajo gion extremely hard, with very resistant foliar et aL 1998). Adaxial stomata were recorded for sheaths. It is evident that in this leaf region, the Tillandsia L. spp. (Souza & Neves 1996), Ca­ intercellular spaces of the spongy parenchyma tops is berteroniana (Schult. f.) Mez (Tomlinson are well developed. The stellate cells produce a 1969), and Brewcaria L.B. Sm., Steyerm. & H. continuous lacuna system from the sheath to the Rob. spp. (H. Robinson pers. comm.). Stomata top of the lamina. placement exclusively on the abaxial surface of the leaves has been interpreted as a strategy to Vascular system minimize water loss caused by convection cur­ Along the whole extension of the leaf, the rents or even light breezes that could remove vascular system is represented by collateral vas­ water vapor from the leaf surface (Nobel et aL cular bundles in a parallel disposition (FIGURE 1975, Nobel 1991, Mauseth 1988). This may 3A, B). Surrounding the large-sized vascular prove to be especially beneficial in the subject bundles are two distinct bundle sheaths. The out­ species, which have stomata not covered by tri­ ermost, the endodermis, consists of a single lay­ chomes. For Ananas comosus (L.) Merr., species er of parenchymatous cells (FIGURE 3B). These of Navia Mart. ex Schult. f. and Vriesea split­ cells are chlorophyllous in the third median of gerberi (Mez) L.B. Sm. & Pittendr., Krauss the lamina and lack chloroplasts in the sheath (1949), Robinson (1969), and Braga (1977), re­ where they contain starch grains. Adjacent and spectively, noted that ordinary epidermal cells internal to the endodermis is a fibrous peri cycle. that surround the stomatal complex show In large vascular bundles, these fibers may sep­ straight walls, thicker than the others. This char­ arate xylem and phloem (FIGURE 3B). The walls acteristic also is observed in the studied species, of the pericycle fibers are thickened, strongly except for V. bituminosa. Krauss (1949) sug­ lignified, and pitted. In the middle-sized and gests that these modified epidermal cells may small-sized vascular bundle fibers of the meso­ help protect the stomata from longitudinal phyll, walls are weakly lignified and thin with stresses applied on the leaves. Peltate trichomes an ample lumen, disposed in such a way as to are typical of Bromeliaceae species (Tomlinson form extensions that interrupt the endodermis 1969). Many of the tank-tillandsioids, among and reach the two portions of the aquiferous hy­ them Vriesea, have trichomes that exhibit a podermis (FIGURE 3A, B). moderately high absorptive capacity (Pittendrigh 1948). Such plants have enlarged leaf sheaths, DISCUSSION which usually keep a large water supply together with organic debris. In mesic environments, the The Bromeliaceae are an angiosperm family tank-bromeliads have leaf sheath surfaces suffi­ predominantly neotropical, distributed along ciently permeable to allow the plant to acquire ecosystems with a range of temperature, precip­ needed nutrients for growth up to the adult phase itation, soil composition, and light incidence and to produce fruits and seeds a few years after (Benzing 1990). Their success in dealing with sprouting (Benzing et aL 1978). these habitats may be related to development of Among the Bromeliaceae, the number of tri­ anatomical and morphological characteristics chomes along the leaf may vary depending on that enable water retention and carbon assimi­ leaf surface (more trichomes on the abaxial sur­ lation and their progressive shift to the epiphytic face) and on leaf region (more trichomes near habit (Schimper 1884, Tomlinson 1969, Medina the sheath). Although trichomes were generally 1990). similar in the five species investigated, some 186 SELBYANA Volume 24(2) 2003

FIGURE 3. Transverse section of foliar lamina and sheath of Vriesea (Xiphion) species (bar = 100 [Lm). A. V. fosteriana, mechanical hypodermis (MH), aquiferous hypodermis (AH), palisade parenchyma (PP), and spongy parenchyma (SP). B. V. bituminosa, epidermis (E), fiber group (arrow), pericyclic fibers (P), endodermis (EN). C. V. triligulata, detail of mechanical hypodermal cells with primary thick wall. ARRUDA & COSTA: VRIESEA FOLIAR ANATOMY 187

TABLE 4. Variability in the number of cell layers of less lignin. Prime characteristics for efficient the mesophyll (hypodermis and chlorophyllous moisture conservation inside the leaves of xe­ parenchyma), at the leaf median third level ob­ rophytic species are precise stomatal control and served among Vriesea (Xiphion) species. impermeable (though not necessarily thick) cu­ ticle (Turner 1994). Hypodermis Chlorophyllous parenchyma water-storage Under the epidermis of the subject species, in Vriesea species tissue Palisade Spongy the median third level and sheath, layers of non­ chlorophyllous cells were observed, forming V. bituminosa 4-5 2-3 10-12 V. josteriana 3-4 2-3 12-14 that what Tomlinson (1969) calls hypodermis. In V. gigantea 5-6 3-4 10-12 bromeliads, this hypodermis has mechanical and V. longiscapa 3-4 1-2 5-6 water-storing functions. Linsbauer (1911) iden­ V. triligulata 4-5 1-2 6-8 tified an epidermal-hypodermal complex, whose typical function was mechanical, with lignifica­ tion reaching the first subepidermal layers. This organization provides support to the leaves and morphological differences were observed in the protects the internal tissues against herbivory middle of the leaf when compared to leaf mor­ and possibly against intense luminosity. At this phology near the sheath. Other studies have re­ same leaf level, the degree of thickening of hy­ ported similar results in relation to structure and podermal cells adjacent to the epidermis varied. distribution of trichomes (Benzing 1970, Benz­ This variation was observed within the same ing et al. 1978). In our study, the leaf sheath has species and among different species. Pita (1997) trichomes with wider shields, more numerous described a similar characteristic for the median and wider wing cells, and denser cytoplasm. third level of the leaves of Dyckia Schultes f. Wing cells with differential distribution of the and Encholirium Mart. ex Schultes f. species radial wall thickness, such as those in Vriesea (Pitcairnioideae), in which she also noted quite triligulata and V. gigantea, are illustrated by reduced lumen cells with much thickened and Tomlinson (1969) for Tillandsia circinnata strongly lignified walls. Schltdl. and Glomeropitcairnia penduliflora At the sheath level, the cells of the mechani­ (Griseb.) Mez. cal hypodermis, mainly those from the abaxial The strong reaction of trichome cells to phe­ surface, are in permanent contact with the ac­ nolic substances test-observed for the study spe­ cumulated water in the tank formed by the leaf cies may be related to protection against herbiv­ sheaths. The presence of phenolic compounds ory. In addition, trichomes may be linked to re­ saturating the cell walls may be beneficial in duced transpiration, at least for some Pitcair­ preventing leaf decay or organismal attack. Pits nioideae, in which they cover the stomata as a on cell walls also demonstrate the benefits of roof (Robinson 1969). When full of air, tri­ such tissue in water and nutrient transport from chomes are highly reflective and reduce the the tank to the internal layers of the hypodermis. amount of incident sunlight on the leaf. For ex­ Water-storing tissues in bromeliads has been re­ ample, some populations of Tillandsia fascicu­ ported by many authors (Krauss 1949, Tomlin­ lata Sw. reflect 42-47% of incident visible light son 1969, Robinson 1969, Sajo et al. 1998). from leaf surface, while mesophytic tank species For Vriesea gigantea, V. fosteriana, and V. reflect no more than 28% of incident light bituminosa, the palisade parenchyma exhibits its (Benzing et al. 1978). This might explain the typical form with high and narrow cells, which small number of trichomes observed at the cen­ may be an adaptation to the intense light in the tral portion of the leaves of the five studied spe­ environment where they occur. Light has proved cies when compared to the xerophytic tillandsias to be a major determinant of the degree of de­ described by Souza and Neves (1996). velopment of such tissue (Nobel et al. 1975, No­ The cuticle layer of the leaf has functions that bel 1991, Mott & Michaelson 1991). Among the are essential for plant survival (Mauseth 1988, study species, V. longiscapa occurs in a mesic Kerstiens 1996, Grubb et al. 1994). The marked habitat (on low parts of trunks, rarely in the can­ thickening and occasional sclerification of the opy), with epiphytic habit. This can explain the epidermal cell walls, especially from the internal loose differentiation of the organization of the periclinal wall, is a typical bromeliad character­ palisade parenchyma. The leaf sheath has only istic reported in all subfamilies (Braga 1977, stellate parenchyma cells, which may be respon­ Souza & Neves 1996, Sajo et al. 1998). During sible for the transport gases found inside leaves, the present study, the presence of lignin was much like an aerenchyma [large intercellular identified with higher intensity in the foliar epi­ spaces] (Matsukura et al. 2000). dermal cells of Vriesea triligulata, both in the The collateral vascular bundles are surround­ median third and sheath; the other species had ed by parenchymatous cells and fibers forming 188 SELBYANA Volume 24(2) 2003 bundle sheaths. Although ontogenetic tests have ACKNOWLEDGMENTS not been performed for the identification of the origin of these layers, for the purpose of this The authors thank Monica Costa for the En­ study, the cells were called endodermis (paren­ glish translation; Fabio R. Scarano, Marccus Al­ chymatous sheath) and pericycle (fibrous ves, and Patricia Pita for critical notes on the sheath). This follows nomenclature from Van first version of the manuscript; and H. Robinson Fleet (1961), Esau (1965), Flores (1975), and and R. Schmidt, for critical review of the final Menezes et al. (2000). version of the manuscript. Our results indicate that the Vriesea species analyzed exhibit the features cited by Tomlinson LITERATURE CITED (1969) as typical to the Bromeliaceae: peltate trichomes, single-layered epidermis, stomata lo­ Benzing, D.H. 1970. Foliar permeability and the ab­ cated only on the abaxial surface of the leaves, sorption of mineral and organic nitrogen by cer­ a hypodermis with mechanical and water-storing tain tank bromeliads. Bot. Gaz. 131(1): 23-31. ---. 1976. Bromeliad trichomes: structure, func­ functions, and collateral vascular bundles. Many tion, and ecological significance. Selbyana 1(4): of the characteristics observed confirm the xe­ 330-348. rophytic nature of the leaves, previously men­ ---. 1990. Vascular Epiphytes. General Biology tioned by other authors. Xerophytic leaves may and Associated Biota. Cambridge University allow establishment of these plants in environ­ Press, Cambridge. ments inhospitable for other plants. The ana­ ---. 2000. Brome1iaceae, Profile for an Adaptive lyzed species presented characteristics typical of Radiation. Cambridge University Press, Cam­ bridge. groups phylogenetically related (e.g., trichomes Benzing, D.H., J. Seemann and A. Renfrow. 1978. The typical of the subfamily Tillandsioideae). Well foliar epidermis in Tillandsioideae (Bromeliaceae) developed spongy parenchyma with stellate cells and its role in habitat selection. Am. J. Bot. 65(3): also are present in a number of species, such as 359-365. the nidularioid-complex, subfamily Bromelioi­ Braga, M.M.N. 1977. Anatomia foliar de Bromeli­ deae. Despite the xeric habitat (rocky outcrops aceae da Campina. Acta Amazon. 3 (supl.): 1-74. and high altitude fields), species of Alcantarea Costa, A. "Vriesea Lindley (Bromeliaceae) na Reserva Ecol6gica de Macae de Cima, Nova Friburgo, RJ, E. Morr. ex Mez are similar to species of Vriesea Brasil. " Master Dissertation, Museu N acionall (Arruda unpubl. data). The Vriesea studied here, Univ. Federal do Rio de Janeiro, Brazil, 1993. however, have an anatomical organization dis­ Dahlgren, R.M.T., H.T. Clifford and P.F. Yeo. 1985. tinct from related atrnospheric-tillandsias. In The Families of the . Springer­ contrast with some Tillandsia investigated by Verlag, Berlin, Heidelberg. Souza and Neves (1996), the analyzed Vriesea Esau, K. 1965. Anatomy of Seed Plants. John Wiley & Sons, New York. present stomata only on the abaxial surface, dor­ Flores, E.M. 1975. Algunos aspectos de anatomia fo­ siventral mesophyll with large development of liar comparada de dos especies de Bromeliaceae spongy parenchyma, and stomata not covered by (Aechmea mexicana Baker y Hechtia glomerata trichomes. This suggests that the anatomical or­ Zucc.). Rev. Bioi. Trop. 23(1): 29-52. ganization of the leaves in Brome1iaceae could Foster, A.S. 1949. Practical Plant Anatomy. D. van be related to environmental pressures as well as Nostrand Inc., New York. to phylogenetics. Sajo et al. (1998) suggested Grant, J.R. 1993. True tillandsias misplaced in Vriesea (Bromeliaceae: Tillandsioideae). Phytologia that the occurrence of similar structures in taxa 75(2): 170-175. with more remote relationships may be the result ---. 1995a. The resurrection of Alcantarea and of similar environmental conditions or conser­ Werauhia, a new genus. Trop. und Subtrop. vation of characteristics from a common ances­ Pfianz. 91: 1-59. tor. ---. 1995b. Addendum to "The resurrection of Al­ The present work is a preliminary contribu­ cantarea and Werauhia, a new genus" (Bromeli­ aceae: Tillandsioideae). Phytologia 78(2): 119- tion to the study of leaf anatomy of Vriesea spe­ 123. cies. The use of anatomical features in the sys­ Grant, J.R. and G. Zijlstra. 1998. An annotated cata­ tematics of the genus remains premature, con­ logue of the generic names of the Bromeliaceae. sidering the large number of existing species and Selbyana 19(1): 91-121. species-complexes. We suggest that detailed Grubb, P.G., I.M. Turner and D.F.R.P. Burslem. 1994. studies will produce better organizing patterns of Mineral nutrient status of coastal hill dipterocarp the internal foliar structure, which may allow the forest and Andinandra belukar in Singapore: anal­ ysis of soil, leaves and litter. J. Trop. Ecol. 10: compilation of more significant data for further 283-335. comprehension of Bromeliaceae biology and Haberlandt, G. 1928. Physiological Plant Anatomy. systematics. Me Millan & Co. Ltd., London. ARRUDA & COSTA: VRIESEA FOLIAR ANATOMY 189

Jensen, W.A. 1962. Botanical Histochemistry. H.H. cord(folia (Compositae). Am. J. Bot. 78(1): 76- Freemann & Co., San Francisco. 79. Johansen, D.A. 1940. Plant Microtechinique. Paul Netolitzki, F. 1935. Das tropische parenchyn. In K. Hoeber Inc., New York. Linsbauer, ed. Handbuch der Pflanzenanatomie. Kerstiens, G. 1996. Cuticular water permeability and Gerbuder Borntraeger, Berlin. its physiological significance. J. Exp. Bot. 47: Nobel, P.S. 1991. Physicochemical and Environmental 1813-1832. Plant Physiology. Academic Press, San Diego. Kraus, J.E. and M. Arduin. 1997. Manual Basico de Nobel, P.S., L.J. Zaragoza and W.K. Smith. 1975. Re­ Metodos em Morfologia Vegetal. Ed. Universi­ lation between mesophylJ surface area, photosyn­ dade Rural, Seropectica. thetic rate and illumination level during develop­ Krauss, B.H. J 949. Anatomy of the vegetative organs ment for leaves of Plectranthus parviflorus Henckel. Plant Physiology 55: 1067-1070. of the pineapple, Ananas comosus (L.) Merr. II. Pita, P.B. "Estudo anatOmico dos orgaos vegetativos The leaf. Bot. Gaz. 110 (3): 333-404. de Dyckia Schultes f. e Encholirium Mart ex Linsbauer, K. 1911. Zur physio10gischen anatomie der Schultes f. (Bromeliaceae) da Serra do Cipo, epidermis und des durchltiftungsapparates der MG." Master Dissertation, Instituto de Biocien­ Bromeliaceen. Sber. Akad. Wiss. Wien 120: 319- cias, Universidade de Sao Paulo, 1997. 348. Pittendrigh, C. 1948. The Bromeliad-Anophe1es-Ma­ Luther, H.E. 2001. De Rebus Bromeliacearum III. Sel­ laria complex in Trinidad. 1. The bromeliad flora. byana 22(1): 34-67. Evolution 2: 58-89. Luther, H.E. and E.Sieff. 1994. De Rebus Bromeli­ Robinson, H. 1969. A monograph on foliar anatomy acearum 1. Selbyana 15(1): 9-93. of the genera Connellia, Cottendorfia and Navia. ---. 1997a. De Rebus Bromeliacearum II. Selby­ Smiths. Cont. Bot. 2: 1-41. ana 18(1): 103-148. Sajo, M.G., S.R. Machado and S.M. Carmello-Guer­ ---. 1997b. De Rebus Bromeliacearum: Addenda reiro. 1998. Aspectos estruturais de folhas de bro­ et corrigenda. Selbyana 18(2): 215. melias e suas implica«oes no agrupamento de es­ Matsukura, M., M. Kawai, K. Toyofuku, R.A. Barrero, pecies. Pp. 101-111 in E.M.C. Leme. Canistrop­ H. Uchimiya and J. Yamaguchi. 2000. Transverse sis, Bromelias da Mata Atlantica. Ed. Salamandra, vein differentiation associated with gas space for­ Rio de Janeiro. mation-fate of the middle cell layer in leaf Sass, J.E. 1951. Botanical Microtechnique. The Iowa sheath development of rice. Ann. Bot. 85: 19-27. State College Press, Iowa. Mauseth, J.D. 1988. Plant Anatomy. The Benjamim Schimper, A. F. W. 1884. Ueber bau und Lebenweise Cunmings Publishing Co. Inc., California. der Epiphyten. Westindiens. Bot. Zbl. 17: 192- Medina, E. 1990. Ecofisiologia y evolucion de las Bro­ 195. Souza, R.C.O.S. and L.J. Neves. 1996. Anatomia foliar meliaceae. Bol. Acad. Nac. Cienc. 59: 71-100. de quatro especies de Tillandsia. Bromelia 3(2): Menezes, N.L., D.C. Silva and G.F.M. Pinna. 2000. 28-39. Fo1ha. pp. 303-325 in B. Apezzato-da -Gloria and Strasburger, E. 1924. Handbook of Practical Botany. S.M. Carmello-Guerreiro, eds. Anatomia Vegetal. George Allen & Nonwin, Ltd., London. Universidade Federal de Vi«osa, Vi«osa. Tomlinson, P.B. 1969. Anatomy of Monocotyledons. Metcalfe, C.R. 1963. Comparative anatomy as a mod­ III. in c.R. Metcalfe, ed. Commelinales-Zingiber­ ern botanical discipline with special reference to ales. Clarendon Press, London. recent advances in the systematic anatomy of Turner, I.M. 1994. Sclerophylly: primary protective? monocotyledons. Adv. Bot. Res. 1: 101-147. Func. Eco!. 8: 1-32. Mott, K.A. and O. Michaelson. 1991. Amphystomy as Van Fleet, D.S. 1961. Histochemistry and function of an adaptation to high light intensity in Ambrosia the endodermis. Bot. Rev. 27: 165-220. Selbyana 24(2): 190-195. 2003.

SPECIES RICHNESS OF V ASCULAR EPIPHYTES IN Two PRIMARY FORESTS AND FALLOWS IN THE BOLIVIAN ANDES

THORSTEN KROMER* AND S. ROB BERT GRADSTEIN Institute of Plant Sciences, University of Gottingen, Untere Karspiile 2, 37073 Gottingen, Germany. E-mail: [email protected]

ABSTRACT. To study the impact of deforestation on vascular epiphyte diversity, we compared species richness in plots in primary forest and adjacent 15-year-old fallows in two different sites in the Yungas of Bolivia, including submontane forest near Sapecho (500-1200 m) and montane forest in the Parque Na­ cional Cotapata (1500-2500 m). Nearly 500 species of epiphytes (25 families, 110 genera) were recorded, and a 1.0 ha plot composed of eight subplots with a total surface of 0.32 ha of montane forest had up to 175 species. These forests rank among the richest worldwide in terms of epiphyte diversity. Fallows had 60-70% fewer species than neighboring natural forest. Numbers of species of orchids, bromeliads, Hy­ menophyllaceae, and Grammitidaceae were much lower in fallows than in primary forest, but hemiepiphytic aroids, Polypodiaceae and Aspleniaceae, were similar. Reduction of epiphytic species diversity in fallows can be explained by structural characteristics of the fallow trees, the lack of a dense moss cover, and the drier microclimate in the fallows.

Key words: epiphytes, vascular epiphytes, biodiversity, canopy studies, tropical rain forest, secondary vegetation, Bolivia

INTRODUCTION METHODS

The montane forests of the tropical Andes are Study Sites among the world's richest ecosystems in terms of number of species (Barthlott et al. 1996). Vas­ The study was conducted in two different cular epiphytes, among them orchids, bromeli­ sites on the eastern slopes of the Andes in the ads, aroids, and ferns, are a key component of Department of La Paz, Bolivia, the so-called these forests, both in terms of species richness "Yungas of La Paz" (FIGURE 1). The first study (Gentry & Dodson 1987, Ibisch 1996, Nieder et site is near the village of Sapecho (450 m; al. 1999) and their roles in water-balance and 15°27'-32'S, 67°18'-23'W), located along the nutrient cycles (Nadkarni 1984, Coxson & Nad­ Alto Beni River at the northeastern base of the karni 1995). These forests are now disappearing Serranfa Marimonos. Temperature in Sapecho rapidly, as the result of increasing human pres­ averages ca. 24-25°C during the day, and annual sures in the region. Deforestation in the tropical rainfall varies from ca. 1500 mm in the valley Andes is ca. 90% or ten times higher than in to 2000 mm on the slopes. The rainy season of October-May alternates with a marked dry pe­ Amazonia (Henderson et al. 1991). The rapid riod of June-September (Elbers 1995). The nat­ destruction poses a major threat to the epiphytic ural forest on the slopes of the Serranfa Mari­ vegetation and calls for measures to safeguard monos is an evergreen or semi-evergreen sub­ their existence. montane forest comprised of trees 30-40 m in Very little is known about effects on the epi­ height and a well developed shrub layer. Tree phyte communities of these forests following de­ diversity averages ca. 120 species per ha (Seidel forestation nor about the ecology of the epi­ 1995). phytes in secondary forests (e.g., Hietz-Seifert Since the 1960s, the population of the Alto et al. 1996, Engwald 1999). This investigation Beni region has increased considerably because is the first one of its kind in the Central Andes. of colonization by immigrants from the coun­ We investigated how the diversity of vascular try's altiplano regions. The increased population epiphyte communities of Bolivian montane for­ has led to the conversion of large tracts of for­ ests is affected by deforestation. We also docu­ ests into agricultural fields. As a result, the lower mented the epiphyte diversity of secondary for­ slopes of the Serranfa Marimonos are covered est. by a mosaic of arable fields and fallow land with trees up to 15 years old and a canopy height of 12-15 m (Kromer 2003). The most common pi­ * Corresponding author. oneer trees of the fallows are Cecropia spp.,

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