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The Structure of Petioles in Pteris (Pteridaceae) Olga Martinez and G. Ignacio Vilte 4400-Salta, Argentina, e-mail: [email protected] The paraphyletic genus and Pteris (Schuettpelz Pryer, 2007; Prado et ah, 2007) includes about 200 mainly pantropical species (Prado and Windisch, American 2000). In the continent there are about 60 species (Tryon and Tryon, we paper 1982). In this report the structure of vascular bundles of the petioles twelve of Pteris species, native or naturalized in the Americas: D.C. P. ciliaris Eaton, P. cretica L., P. deflexa Link, P. denticulata Sw., P. ensiformis Burm.f., P. exigua O.G. Martinez and Prado and (Martinez Prado, 2011), inermis P. J. de (Rosenst.) la Sota, P. multifida Poir., P. mutilata L., P. quadriaurita Retz., P. Raddi and tristicula P. vittata L. Many authors consider the structure of vascular bundles significant in identifying taxonomic different groups, including Ogura White (1972), (1974), and De Lin Vol Gragano (1977, 1978), Hernandez et al. (2001), et al. (2006), Hernandez-Hernandez among et al. (2007), Srivastava (2008a, 2008b), others. Ogura (1972) describe the structure of petioles in Pteris as being made only by one along stele their entire course, or several the base some at that point meet. at and De Lin Vol (1977) present a key Taiwan on to ferns the basis of petiole and structure, they provide number diagnostic value the and shape to of vascular bundles, sclerenchyma distribution, presence and number of adaxial grooves, and ventilation areas indument. Lin and De Vol (1978) describe the petiole structure of nine Pteris species (including and "U" P. multifida) recognize "V", "Q"-shaped or vascular bundles. Gragano et al. (2001) indicate that the petiole vascular bundles and of P. denticulata P. leptophylla Sw. are "U"-shaped, and assume Q an inverted shape in propinqua Agardh. Bondada P. et (2006) al. J. report that the petiole in P. vittata has a "U"-shaped vascular bundle. In cases, all xylem the is described with the ends folded of the "hippocampus" type. There have been no prior anatomical studies of most of the species treated in we work, this so expect our add results will the anatomical and to phylogenetic knowledge about genus. this AMERICAN FERN VOLUME NUMBER JOURNAL: 102 (2012) 1 Materials and Methods The studies were conducted on herbarium material provided by the following institutions: BA, BM, CTES, G, K, LP, LPB, MCNS, NY, P, S, SI, UNR, US SP, and Z. Living specimens were collected in Argentina and were MCNS deposited in the Herbarium. we For anatomical studies, considered three areas of the petiole: basal (next to middle and the rhizome), (half of the petiole) distal (next to the blade). made were with microtome and Histological sections a rotary freehand, stained with Safranin-Fast Green and mounted in Canada balsam. The histochemical tests used to detect cutin and suberin, lignin and tannins were Sudan and III To fluoroglucine Fe3Cl with CaCOg, respectively (D 'Ambrogio Argiieso, 1986). we observe xylem macerated using the Jeffrey technique (Jeffrey, 1917). Observations, illustrations and photographs were done with a light Zeiss Standard 16 microscope and a scanning electron microscope of the JEOL JSM 6480LL model, belonging the Universidad Nacional de Salta (Argentina). to SEM Samples were an observations subjected increasing alcohol for to series, and The was then dried point with CO2. metallization carried out to critical with a thin gold-palladium coating. For the schemes, the conducting tissues are represented by Metcalfe and Chalk (1950), as suggested by Martinez (2003). made were with camera Illustrations the aid of a lucida. CUBA. Material Studied. P. ciliaris.— East: without locality, 150 m, 9/VI/1915, Ekman 5364 Santiago de Cuba: 1843-4, Linden 1924 HAITI. South: (S); (P). Ekman Jeremie, Massif de Hotte, western group, 800 m, 22/VII/1948, 10403 la Ekman Idem, 700 m, 25/XII/1926, 7415 (BM). (G); ARGENTINA. Quebrada San cre?ica.— Dpto. de Lorenzo, P. Salta: Capital, 1500 m, 10/III/2002, Martinez 913 (MCNS). MEXICO. Distrito Federal: Canada de Contreras, 2800 m, 30/IV/1966, Rzedowski 22 217 PERU. Amazonas: (LP). Wurdack Chachapoyas, 5/VI/1962, 776 (K). ARGENTINA. Manuel camino P. de_/7exa.— Jujuy: Dpto. Belgrano, a Tiraxi, km RN 9 of lO/XII/1998, Morrone 3202 (CTES). Salta: Dpto. Santa Victoria, 9, W64 Parque Nacional Abra de Minas, S 22 27.4' 44.4', 1400 m, 10/ Baritii, VIII/2009, Martinez 1831 (MCNS). Tucuman: Dpto. Monteros, Qda. del et al. Portugues, 1550 m, Martinez 30/XI/1999 (MCNS). 703, ARGENTINA. denticulata.— Dpto. Ledesma, Parque Nacional P. Jujuy: Calilegua, camino a Valle Grande, 20/IV/2002, Martinez 914 (MCNS). Misiones: Dpto. Candelaria, Candelaria, 8/IX/1993, Arbo al 6007 BOLIVIA. Santa et (LP). W63 Cruz: Valle Grande, SI8 48' 49', 1000 m, 24/V/1996, Kessler 6043 et al. CUBA. Ekman (LPB); Oriente: Pinar de Yigiie, 500 m. 29/III/1915, 5138 (S). ensiformis.—WYVm STATES OF AMERICA. California: Los Angeles, P. 20/XI/2002, Hoshizaky (MCNS JAPAN. Hong Kong: Tai Po Kau 1814). s.n. TAIWAN. Forest Reserve, 21/XI/1980, Kramer 8225 Satun, ElOO 10' et al. (Z). N 6 42', 100 m, 27/Vni/1995, Larsen 46081 (NY). et al. ARGENTINA. exigua.— Dpto. Ledesma, camino Calilegua-San P. Jujuy: Francisco, 17/III/2009, Martinez y Chambi 1802 (MCNS), Salta: Dpto. Capital, MARTINEZ & VILTE: PETIOLE STRUCTURE IN PTERIS Quebrada Los Berros, 1500 m, ll/IV/2002, Martinez 881 (MCNS), Tucuman: Dpto. Burruyacu, Cerro Nogalito, 12/VI/1929. Venturi 8879 (SI). inermis.-ARGENTlNA. P. Jujuy: Dpto. Ledesma, camino a Valle Grande, 22/11/1972, Cabrera 22384 et al. (LP), Parque Nacional RP Calilegua, 83 S W 23 41,9' 64 52,8',' 1365 m, 17/III/2009, Martinez Chambi 1778 (MCNS). y Salta: Dpto. Capital, Quebrada de San Lorenzo, S 24 'W 43.1 65 30.5', 10/VII/ 2010, Martinez Chambi 1919 (MCNS). y ARGENTINA. multifida.— P. Chaco: Dpto. Primero de Mayo: Colonia Bemtez, Romero IV/1983, BOLIVIA. Santa Cruz 1 (LP). de la Sierra: Biocentro Gembe, 400 m, 02/IV/2010, Martinez 1872 (MCNS). CUBA. La Habana: Guanabacoa Ekman 7/XII/1921, 13543 (S). CUBA. mutilata.— P. La Habana: Lomas do Ekman ll/VI/1914, la Jaula, 1313 HAITI. West: Gonave (S). Island, VIII/1927, Eyerdam 247 PUERTO (CA). RICO. W N Rio Abajo State Forest, 18 20,3' 66 42,0'. 4/VI/1999. Acevedo-Rodrieuez 10657 (US). ARGENTINA. quadriaurita.— P. Jujuy: Dpto. Ledesma, Parque Nacional Cahlegua, ruta provincial Mesada Las Colmcnas, 83, Martinez v Guerra 1993 24/VIII/2010 (MCNS). Salta: Dpto. Oran, Los Naranjos, no San a orillas del Andres, 1150 m, Martinez Prada y 1746, 18/06/2008 (MCNS); Rio Pescndo, km de 8 Arazayal, 25/X/1970, Vervoorst Cuezzo 7804 y (BA). ARGENTINA. P. tristicula.— Corrientes: Ituzaingo, Arrovo Garape v rio km E Parana, 45 de Ituzaingo, Tressens 23-24/10/1974 ot 408, al. (LP). Salta: W Dpto. Oran, Rfo Blanquito a los Naranjos, S 23 41 .7' 64 51.9', 610 m, Martinez Prada 1697, 17/VI/2008 (MCNS). BRAZIL. y Rio de Sao Janeiro. Carlos, Fazenda NE Canchim, km. Sao ca. 8 of Carlos, 22/VI/1961, Eiten 3182 et al. (SP). ARGENTINA. vittata.— P. Entre Dpto. Rosario Ri'os: del Talar, Acobal Soraru 31/III/1963 39, (LP). Jujuy: Dpto. Ledesma, Libertador General San Martin 600 m, Martinez 13/V/2007 1399, (MCNS). Santa Fe: Facultad de Ciencias Agrarias, Universidad Nacional de Rosario, Lewis (UNR 1585, 25/III/1983 4624). Results Externally, the petioles are green, yellow with macules brown, or always with a dark base. Their length between varies 1/2-2/3 of the total length of the The fronds. petioles of the fronds fertile are longer than those of the sterile mm The fronds. diameter middle in the ranges from ud 1 in P. ensiformis to ^ mm 20 in P. deflexa. In cross section, petioles (Figs. 1-18) have bases with triangular or tetragonal boundaries (Figs. and 1, 4, 7, 10, 13, 16), subcircular middle (Figs. 2, 5, 8, 11, upper 14, 17) to sections (Figs. with simple 3, 6, 9, 12, 15, 18) a groove on the adaxial This side. groove runs lengthwise over the entire axis including the with rachis, a considerable depth from the lower basal third, and, as in the Two base, usually it is sjjghtly concave. continuous white lines parallel to this The indumentum of petioles consists of scales and trichomes. Scales are common in the base, similar the rhizomatic to structure; they are basifixed, VOLUME NUMBER AMERICAN FERN JOURNAL: 102 (2012) 1 MARTfNEZ & VILTE: PETIOLE STRUCTURE IN PTERIS shaped of Pteris erotica L. 20. Stele in a U-shaped of Pteris vittata L. showing scales around the petiole. 21. Stele in a U-sahped Pteris quadriaurita Retz. with ends largely elongated and bent over main the shaft. 22. Stele inverted Q-shaped of Pteris exigua O.G. Martinez and Prado with ). show In cross section (Fig. 19-22), petioles a cortex formed -from the outside in- of a monostratified epidermis covered by a thick cuticle, and 2-18 layers of sclerenchyma and parenchyma whole (Fig. 23). In large plants as P. deflexa the cortex is sclerified. This subepidermal supporting tissue has two gaps along common formed by The the petiole the ventilation areas. presence of tannins is which brown in the cortex, gives the mature petioles a to dark color. mm young and In fragile petioles, of 1 in diameter, ventilation areas are substomatal chambers, while in the robust petioles these areas are composed of parenchymatous with few tissue, intercellular spaces (Fig. 24). In the medulla, depending on the cross section area, there are one or two vascular bundles. In P. cretica and P. multifida, there are two bundles on the base that fuse in the lower third of the petiole by the V-shaped abaxial ends 1-3). (Fig. The nine remaining species have monostelic petioles along the entire shaft. The "V"-shaped stele is (Fig. 19) in P. ensiformis, P. ciliaris, P. cretica, P. and multifida P. mutilata, "U"-shaped (Figs. 20, 21) in P. vittata and P. and denticulata, P. tristicula, P. quadriaurita, "inverted Il-shaped" (Fig. 22) in P. deflexa, P. exigua and P. inermis. The opening of the vascular bundle is located towards the adaxial side in cases. all The vascular bundle surrounded by externally the monostratified is endodermis with thickening on and the radial walls a pericycle consisting of (l-)2-3 layers surrounding the phloem and xylem Morpholog- cell (Fig. 25). xylem P ically, the is characterized by having curved ends in vittata or long bent ends which sometimes make contact with the main axis in P. denticulata, and Around P. tristicula P. quadriaurita. the vascular bundles, strands of fibers 4-12 which consist of cells, are isolated in small plants or together in a continuous discontinuous depending on or ring the age of plants. Depending on shape and xylem we the of the vascular strands structure, propose a classification of the vascular bundles in four possible types: Type V-shaped with ends xylem (Fig. 19), the of the folded in a short I. hook, with protoxylem three areas: P. ciliaris, P. cretica, P. ensiformis, P. and multifida P. mutilata. Type U-shaped, with two forms: type with Il-a (Figs. 20, 26) shortly II. curved xylem ends and with protoxylem five to six areas observed in P. MARTINEZ STRUCTURE & VILTE: FETIOLR IN PTERIS The oxtornal morphological characters of the Pteris petioles, such as a channel and two central lines covering the ventilation areas, have also been AMERICAN FERN VOLUME NUMBER JOURNAL: 102 (2012) 1 observed Asplenium, in Christella, Dennstaedtia, Microlepia, Pteridium, and others by Lin and De Vol The brown purple (1978). to coloration of petioles, a color also frequent in Adiantum, Cheilanthes and Pytirogramma, among others, is attributed to the presence of tannins. The number an of steles is important characteristic for rapid identification of different taxonomic groups. Lin and De Vol (1978) characterized Pteridaceae by two the presence of vascular bundles in the base of petioles that fuse upwards. This has been found two and in species, P. cretica P. multifida, whose xylem bundles join by the abaxial ends in the lower basal third of the Ogura such development shaft. (1972) finds of the vascular bundle in Onoclea, Woodsia and Athyrium, and "Onoclea the form." calls it The twelve species studied have a monostelic axis from the middle petiole, although the shape According stele varies. to the classification proposed by Ogura (1972) for the monostelic axes, P. ensiformis, P. ciliaris, P. cretica, P. and multifida mutilata Hymenophyllaceae P. present type whereas stele, P. denticulata, P. quadriaurita and have Loxoma P. tristicula type vascular and strand, exigua and P. deflexa, P. P. inermis present the Pteris podophylla type. This author also describes two distinct types for the genus the Pteris, Loxoma type in P. longifolia Wall., P. tremula R. Br. and P. flavellata Sieb. et Zucc. and the podophylla same Pteris type for the species. According to the classification suggested in this study, the type or V- I, shaped Hymenophyllaceae type (Ogura has been mentioned 1972), for Adiantum (Pteridaceae) and identified by Bidin and Walker (1985) as "saucer" shaped. Ogura (1972) considers this type to be a derivative of the Loxoma type. Lin and De Vol (1978) describe a petiole cross section of P. multifida that matches that described here for the species. The type U-shaped Loxoma or type, has been reported II, for P. denticulata, P. excelsa Gaudich., P. leptophylla Sw., semipinnata and P. L. Pteris vittata and De (Lin Vol, 1977, 1978; Gragano et al, 2001; Bondada al, Ogura et 2006). mentioned Loxoma (1972) the existence of modified forms within the type, due to the presence of a varying number of protoxylem areas, five in P. i.e., and and we longifolia L. four to eight in P. tremula P. flavellata. In this study, found number differences in the of protoxylem bundles and ends in the of the we xylem, so proposed two and The different subtypes, subtype a b. II first is characteristic of P. vittata while the subtype characterized by having Il-b, is ends fused to the main shaft, which gives the appearance of rounded ends, and why Ogura this is likely (1972) considered the species of Pteris mentioned above have xylem to a devoid of hooks. The type inverted fi-shaped, has been reported propinqua (Gragano III, for P. et al, 2001) and P. wallichiana Agardh (Lin and De Vol. 1978). This J. monostelic type considered by Ogura is (1972) as a simple form derived from a polystelic type comprising several meristeles arranged in a horseshoe, called Saccoloma. Also and Gifford Foster (1996) qualify the monostelic condition of vascular bundles and as primitive, the polystelic condition as specialized. According and to this criterion considering that several interruptions caused by parenchyma bands have been found form and in the Q. the fact that the MARTINEZ STRUCTURE & VILTE: PETIOLE IN PTERIS numerous protoxylem groups we may are distributed regularly, consider this type to be a derivative form within the genus The presence Pteris. of parenchyma in the xylem has been cited in the rhizome of Astrolepis sinuata Benham Windham ex Sw.) D.M. & and (Lag. (Scheiner but no Carlquist, 1997], studies describing have been this feature in petioles found. Wyk and van mention Potgieter (1992) the existence of intercellular pectic many projections in the petioles of including some These ferns, Pteris species. structures have not been recorded in the specimens studied, although specific with more future studies precise techniques could detect them. Inthesame way, the ultrastructural details of the xylem of these species could be studied. The work show results of this that Pteris vittata has different characteristics in the vascular bundles from other species of Martinez showed Pteris. (2010) that spore characteristics of P. vittata are different from other species of With Pteris. the spore differences, these vascular bundle results reaffirm the results of molecular by Prado which studies determined et al. (2007), that to achieve monophyly of Pteris P. vittata should be segregated from other species of Pteris.