IAWA BULLETIN 1976/3 RADIAL VESSELS IN RAYS EDITORIAL by On Tuesday, June 7 of this year, Dr. Wilfred A. Cote personally handed over the essential IAWA records to us thereby officially transferring the office of the International G.J.C.M. van Vlietl Association of Wood Anatomists to the Netherlands, after it had been at for six and a half successful years. Dr. Cote's In the course of a wood anatomical survey of the axial vessel, deviating from its vertical course and ob- efforts on behalf of the Association, and tltose of his co-editor Combretaceae (van Vliet, in preparation), radial liquely passing through a ray. Chalk and Chattaway Dr. Carl de Zeeuw, did not cease at this juncture, however, since vessels were found in the rays of the genera Quisqualis (1933) and Carlquist (1960) referred tci such cells as they had agreed to complete the 1976 sequence of IAWA and Combretum: scandent or erect members of this perforated ray cells . McLean and Richardson (1973) Bulletins, albeit without the editorial responsibility, now resting family. To my knowledge this feature has never been used the term "vascular ray cell." The latter term is, in on our inexperienced shoulders. recorded in the literature before. However, the radial my opinion, most confusing because the term vascu- It is difficult to describe in a short editorial the full significance vessels are common in most of the wood samples lar rays is often used to refer to the entire ray tissue of the work that Dr. Cote has done for our Association. The studied of these two closely related genera. of the secondary xylem. Perforated ray cells of this results can be seen in a regular quarterly bulletin of excellent In Quisqualis and Combrelum the rays are uni- or type, although not uncommon in a number of biseriate, rarely triseriate. They are mainly homo- families, have not been observed in Combretum or Quis- quality and lay-out; a vast increase of the membership from geneous and composed of procumbent cells only, but qualis, or in other Combretaceae studied by me. about 160 to 270, and a doubling of the number of library may also contain erect cells, particularly in the Carlquist (1961) stated that perforated ray cells of subscriptions from 20 to 40 during his term of office. These are juvenile wood near the pith. In tangential sections the common type are vessel members, derived from hard facts which are self-explanatory with regard to the simple perforations can be found in the tangential ray ray initials, and that they are somewhat intermediate involvement and energy spent by our former Executive ce ll walls (Fig . 2), and when studying radial sections between ray cells and vessel elements in morphology. Secretary. However, these achievements, although of vital (F ig . 1 and 3), radial files ofcells are present which are The lateral wall pits are like those of the vessels importance for the IAWA, only show the tip of the iceberg of all connected through perforations in the tangential (Carlquist, 1960), bordered and alternate, although that went on at Syracuse. The major aim of the Association-to walls. (The perforations occur in oblique walls.) Of the pits are smaller and have reduced borders (cf. provide contacts between wood anatomists-was impressively these radial files, mostly only one terminal cell was Fig. 2). served by Or. Cote as many of you have experienced in observed with a perforation in one tangential wall For the radial vessel elements reported here, correspondence with his office at Syracuse, and as we can testify only and one perforation in a radial wall, leading to a similar suggestions can be advanced. There can be no from the extensive files now at Leiden. The IAWA certainly vascular tracheid or a very narrow vessel. In one case, doubt about the fact that they arose from ray initials, both terminal cells of a radial file were observed, and and their morphology recalls ordinary ray cells in owes a great debt of gratitude to Dr. Cote and to those who each was connected with an axial element, through a shape and size. However, the presence of perfora- assisted him. perforation (Fig . 1). A perforation in the radial wall of tions and vestured pits (Fig. 4 and 6), as well as the fact To succeed Dr. Coteand Dr. de Zeeuw is, for obvious reasons, a cell somewhere in the middle of a radial vessel has that they usually form a radial tube of substantial a pleasant as well as a very difficult task. Pleasant and easy, never been found. The maximum number of cells length, all constitute characters typical for true vessel because of the fine example set, which simply has to be followed. recorded for a radial vessel of which no terminal cells members. Difficult, because it will be very hard to come up to the high were visible was 29 cells. Mostly these radial files of The presence of these radial vessels in the genera Syracuse standards. In this first editorial it is therefore ray vessels are in one level; however, the vessels shift Combrelum and Quisqualis has many aspects that need appropriate to ask your help and support for our efforts to to a lower or higher level (Fig . 1). Branching of a radial further attention. It would be interesting to study the maintain the IAWA activities at the same high level both vessel has been observed once: one of the radial ontogeny and morphogenesis of these radial vessels . qualitatively and quantitatively. We need support from all vessels having a perforation of the ventral wall and Moreover, the general theories on the determination members in the field of increasing the circulation of the Bulletin, being connected through a vertical ray vessel element of xylem mother cells to vessel elements and on vessel in providing copy for scientific contributions as well as notes and with another radial vessel running two ray cell levels differentiation should be tested for these genera which combine a radial and an axial vessel system. requests; the last but not least we will appreciate your lo wer. Radial vessels have been observed in the fo llowing species: Quisqualis lalialata (Engl.) Exell, Functional aspects would also deserve further understanding and clemency if, for financial or other reasons, Co mbrelum collinum Fresen, C. erylhrophyllum (Burch.) attention. The taxonomic and diagnostic implications we will sometimes fail in our aims to achieve the results so Sand., C. frulico sum (Loefl.) Stuntz., C. gallabat ense of this character will be discussed in a future paper successfully obtained by our predecessors. Schweinf., C. imberbe Wawra, C. kraussii Hoechst., C. (van Vliet, in preparation). molle R. Br. and C. zenkeri Engl. and Diels. They were Pieter Baas not observed in the samples studied of Combretum This study was made possible through financial ap ic ulalum Sond. and C. multispicalum Engl. and Diels. support from the Netherlands Organization for the Peter B. Laming Perforations in ray cells have been described in the Advancement of Pure Research (Z .W .O). Office of the Executive Secretary literature before, but these perforations were always Rijksherbarium found in the radial walls between one ray cell and a Schelpenkade 6, Leiden ve ssel member. Such a ray cell always has two per- The Netherlands forations, one in each radial longitudinal wall and serves as a link between two vessel members of an IRijksherbarium, Schelpenkade 6, Leiden, The Netherlands. 35 IAWA BULLETIN • 1976 / 3 IAWA BULLETIN • 197613 34 References 4 . McLean, J.D . and Richardson, P.E. 1. Carlquist, S. Vascular ray cells in woody stems. Phytomor- Wood anatomy of Asteraceae (Compositae) . phology 23 (1-2): 59-64, 1973. Tropical Woods 133: 54-84, 1960. 5 . van Vliet, G.J.C.M. 2 . Carlquist, S. Wood anatomy of the Combretaceae. Blumea (in Comparative Plant Anatomy. New York, 1961. prepar.a tion). 3 . Chalk, L. and Chattaway, M .M . Perforated ray cells . Proc. R. Soc. B 133: 82-92, 1933. Figures 1, 2, 5 : Combrelum molle R. Br. Figures 3, 4, 6 : Quisqualis latialata (Engl.) . Exell. Figure 1. Radial section. Light micrograph, showing a file of radial vessel elements (white arrows) of which both terminal cells have a perforation (p) in the radial wall, connecting them with a vascular tracheid. Both terminal cells are on a level dif- ferent from the greater part of the radial vessel. On the left a terminal cell and some elements of another radial vessef (black arrows) are visible. x 600. Figure 2. Tangential section. Light micrograph, showing a perforation (p) in the tangential wall of a ray cell. x 600. Figure 3. Radial section. Light micrograph, showing 'erect' radial vessel elements. The terminal cell has a perforation (p) in the radial wall. x 800. Figure 4. Radial surface. Scanning electron micrograph, showing a perforation rim in a radial vessel (arrows). Note the vestured pits. x 3100. Figure 5. Radial section. Light micrograph, showing vestured radial vessel to parenchyma pits. On the right a perforation in a tangential wall (arrow). x 2400. Figure 6. Radial surface. Scanning electron micrograph, showing radial vessel elements with a perforation in the radial (p) and the tangential wall (arrow), and a narrow vessel (v) with a perforation (x) probably leading to a radial vessel. Note the vestured pits in the radial and axial vessel elements and the unvestured pits in the ray parenchyma cells. x 900. IAWA BULLETIN • 197613 36 3 7 IAWA BULLETIN • 19 76/3 JUVENILE CHARACTERS IN THE WOOD OF CERTAIN RUBIACEAE WITH SPECIAL primary xylem. When such a shortening is absent, 1746, Uw 20851 (Plate I: 7, 8, 9) . This collection was an abrupt change in length of the cambial initials has made in Serra de Bocaina, E.