Downloaded from Brill.Com10/04/2021 02:20:31PM Via Free Access 140 IAWA Journal, Vol
Total Page：16
File Type：pdf, Size：1020Kb
IAWA Journal, Vol. 28 (2), 2007: 139-172 MENISPERMACEAE WOOD ANATOMY AND CAMBIAL VARIANTS Frederic M.B. Jacques* and Dario De Franceschi Museum National d'Histoire Naturelle, Departement Histoire de la Terre, CP 38, UMR 5143 CNRS-USM 0203 Paleobiodiversite et Paleoenvironnements, 8 rue Buffon, 75231 Paris Cedex 05, France - *Corresponding author [E-mail: [email protected]] SUMMARY Menispermaceae are comprised almost entirely of lianas. Study of its wood anatomy is of interest for understanding adaptation to the liana habit. We set out here to present a general overview of Menispermaceae wood. The wood anatomy of 77 species of 44 genera, representative of an tribes and from an continents, is described. The wood of 18 of these genera was previously unknown. We observed two secondary growth types within the family: wood with successive cambia and wood with a single cambium. The distribution of these types is partly consistent with the c1assification of the family by Diels. General characters of the family are: wide rays, enlarged vessel pits near the perforation plates, and pitted tyloses. The fun range of wood anatomical diversity is given in Table 1. Key words: Menispermaceae, wood, successive cambia, cambial variants. INTRODUCTION The bark of some species of Menispermaceae is wen known for its use in the preparation of dart poisons in South America, named curare. Although Menispermaceae wood is an important material for pharmacological studies for identifying new alkaloids (N'Guyen, pers. comm.), this special interest of phytochemists contrasts with the relative paucity of anatomical knowledge of the family. A better knowledge of Menispermaceae wood is also important for palaeobotanical studies, to enable fossil woods of this family to be more precisely identified (Vozenin-Serra et al. 1989; Poole & Wilkinson 2000). As is true for most liana wood, Menispermaceae wood has not been studied often. However, previous studies showed that it exhibits some interesting features (Santos 1928, 1931; Mennega 1982; Carlquist 1996): successive cambia occur in most Menis permaceae. Carlquist (1996) even proposed that successive cambia could be the only secondary growth type in Menispermaceae. Fibraurea tinctoria, studied here for the first time, CosciniumJenestratum, recorded by Eichler as early as 1864, and several other taxa show, however, that this assumption is untenable. This study aims to extend the survey of Menispermaceae wood anatomy. A total of 77 species of 44 genera were studied and the wood of 18 genera is described here for the first time. To allow easy data retrieval for phylogeny reconstruction, we recorded the wood anatomy of each species in detail, even if they are very similar to others. Downloaded from Brill.com10/04/2021 02:20:31PM via free access 140 IAWA Journal, Vol. 28 (2), 2007 Carlquist (1996) suggested the special significance ofMenispermaceae wood in the phylogeny ofRanunculales, part ofthe basal Eudicots, because the farnily shows 'primi tive' features (presence oftracheids) and 'derivative' ones (successive cambia). The different types of cambial variants of Menispermaceae wood will be discussed on the basis of our broad survey. MATERIALS AND METHODS The wood specimens studied came from different collections: Paris Herbarium (P), Utrecht xylarium (Uw), Leiden xylarium (Lw), Tervuren xylarium (Tw) and personal collection in the field. All identifications were checked by studying the corresponding herbarium vouchers in the different collections. Some sampies were collected especially for wood anatomy studies, others came from small twigs of herbarium specimens (P). All specimens studied are listed in the Appendix (pages 169-172). Dry wood sampies were rehydrated in boiling water and sectioned on a sliding mi crotome. The sections were stained with iodine green, and mounted in glycerine jelly and/or Canada balsam after dehydration through graded a1cohol and toluene series. All descriptions follow the terminology of the IAWA Committee (1989). As the wood structure of the majority of the studied species showed very wide rays, it was difficult to determine some of the usual descriptive quantitative characters, such as number of vessels/sq.mm, number of rays/mm, etc. The bark was carefully observed in some cases for a better understanding of the special structure of the wood (successive cambia, protruding phloem rays). The averages of the measurements were ca1culated on the basis of all available specimens and most of the time the photomicrographs inc1uded here only partly rep resent the characteristics of the species. Especially in cross sections we could observe important variations in the size of vessel elements from different collections and even in the different parts of the same section from pith to bark. As Menispermaceae wood has some very special features, we feIt the need to specify the meaning of some terms used in the descriptions to avoid ambiguities. The terms are explained and illustrated in Figure 1. - Bundle: part of secondary xylem formed between two adjacent rays and within one cambial production unit. - Sc1erotic fibres: sc1ereid layers found extemal to secondary phloem. This tissue is referred to as sc1erenchyma by some authors. - Tangential cortical parenchyma: parenchyma in continuous tangential bands between two successive cambial production units. We do not use Carlquist's term (2001) 'con junctive tissue' because it refers to both the sc1erotic fibres and the tangential phel lodermal parenchyma. - Ray cells in special arrangement: ray cells with terminal oblique walls and seemingly in continuity from one row to the nextone as seen in transverse section (see Fig. lOH). - High ray: when a ray is more than 1 mm high. Downloaded from Brill.com10/04/2021 02:20:31PM via free access Jacques & De Franceschi - Menispermaceae - wood anatomy 141 xylem bundle (3rd CPU) tangential cortical parenchyma sclerotic fibres phloem ray secondary phloem of the 2nd bundle series 2nd cambium zone 0+-...:---- xylem ray xylem bundle (2nd CPU) tangential cortical parenchyma pericyclic fibres primary phloem phloem ray '---- secondary phloem of the 1st bundle series 1st cambium zone xylem ray xylem bundle (1st CPU) primary xylem medulla Figure 1. Diagram explaining the terms used in the descriptions with respect to the special struc ture associated with successive cambia. epu: cambial production unit. RESULTS AND DISeUSSION The pith shows anatomical variation, depending on the genus or the species. Some secretory canals (Caryomene) or laticifers (Borismene, Dioscoreophyllum, Tinomis cium) can be observed in the medulla (Fig. 6E). Numerous calcium oxalate crystals occur in some species, often in the ray cells. The protoxylem pole number varies from 8 (Syntriandrum) to 87 (Elephantomene) and is between 20 and 40 for the majority of specimens. The poles are subtended by a crescent-shaped sclerification on their inner side (Abuta spp., Anomospermum, Arcangelisia, etc.), on their outer side (Chondro dendron, Cissampelos, Cocculus, etc.) or on both sides (Elephantomene). A sclerified medullar ring occurs in the stern of Sciadotenia. The secondary xylem of all observed species shares the following features: Vessel elements with horizontal or oblique simple perforation plates; alternate and small intervessel pits; vasicentric tracheids always present and more or less abundant depending on the species; fibres with distinct bordered pits (4-7 !-lm) in both radial and Downloaded from Brill.com10/04/2021 02:20:31PM via free access 142 IAWA Journal, Val. 28 (2), 2007 tangential walls; fibre walls thin to thick; rays commonly multiseriate and more than 1 mm high, and there are less than 4 rays/tangential mm. The majority ofthe species studied shows successive cambia. Other frequent features are: enlarged pits near perforation plates; generally square to procumbent ray cells; diffuse-in-aggregate axial parenchyma, often in short tangentiallines. No vessel-ray pits were observed, because there is commonly no contact between vessels and rays. As the Menispermaceae species are mainly lianas, the wood structure has some 'non standard' characters. The specific wood characters are summarized in Table 1 (page 156). These characters are illustrated in Figures 2-14, with genera and species arranged in alphabetical order. The bark plays an important role in the formation of successive cambia (see discus sion below), and encompasses unexpected tissues in the different parts of the stern. The sclerotic pericyclic fibres are found in all species, and in wood with successive cambia they are observed between the first and second cambial unit ring. Except in Hyperbaena and Parabaena, the secondary phloem rays protrude into the xylem rays, deeply to near the central part of the stern (Arcangelisia). In a xylem bundle, vessels are homogeneous in size or of increasing size towards the external part of the bundle. The width of the bundles can be estimated by the number of vessels present tangentially. In rays, cells can be oriented parallel to the axis of the ray or obliquely. Sometimes, a new ray can appear in a bundle. The crystals observed in the bark are of the same type as in the xylem rays. Cambial variants Carlquist (1996) showed that the term 'successive cambia' was more accurate than 'included phloem' (proposed by Metcalfe & Chalk in 1950) to describe this special growth. We agree with his analysis because new secondary cambial units appear suc cessively in the pericycle or cortex by the activity of new cambial zones. Successive