Botanical.juuma1 zyxwvutsrqpon dthe Linnean zyxwvutsrq Society zyxwvutsrqpon (1999), zyxwvuts 130: zyxwvuts 395-410. With 7 figures Article ID: bojl. 1998.0244, available online at http://www.idealibrary.com on zyxw I BE zyxw FL @ c zyx Morphological and architectural features of young zyxw Nothofagus pumilio (Poepp. & End.) Krasser (Fagaceae) J. PUNTIEFU1,3*, E. WFAELE', P. MARTINEZ', D. BARTHELEMY' AND c. BRIO" ' Cmtro Regional Universitario Bariloche, Universidad Nacional del Comahue, Unidad Postal U.N C., 8400 Bariloche, Argentina, 2Uniti de Modilisation des Plantes, CIRAD/wrRA, 'AMAP-ForiY, BP 5035, 34032 Montpellier, Cddex 1, France, 31nvestkador del Consgo Nacional de Investkaciones Cient5ca.s y Ecnicas, ATentina Received September 1998, accepted for Publication December 1 9 9 8 The morphology and architecture of young Nothojiis pumilio plants growing as understorey and in a cleared area were assessed. Length, number of internodes, presence of branches and apex condition were registered for each growth unit (GU) in the sampled plant. GUS were grouped according to branching order and age of the bearing axis. Understorey plants were seven years old and had a short trunk bearing 2-3 orders of branches; all of their most recent GUS were horizontal and of comparable size. Plants growing in the cleared area were 10-16 years old and had a vigorous vertical and dominant trunk bearing 4-5 orders of less vigorous, horizontal branches. Plants from the cleared area showed signs of having had comparable-size GUS in all of their axes at a younger stage of growth. N. pumilzo plants appear to start their growth with the production of short GUS in all of their axes irrespective of the light conditions. In contrast, the development of a vertical, vigorous trunk, seems to be restricted to plants growing in open environments. 0 1999 The Linnean Society of hiidon ADDITIONAL KEY WORDS:-apex abortion - axis differentiation -branching probability - growth unit - internode. CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . 396 Material and methods . . . . . . . . . . . . . . . . . . . 396 Results . . . . . . . . . . . . . . . . . . . . . . . . 399 General morphological and architectural features of N. pumilio . . . . . 399 Development of young plants at different sites . . . . . . . . . . 399 Discussion . . . . . . . . . . . . . . . . . . . . . . . 404 Developmental patterns in young N. pumilio plants . . . . . . . . . 404 Development and shade tolerance in zyxwv JY pumilio . . . . . . . . . . 406 Conclusions . . . . . . . . . . . . . . . . . . . . . 407 Acknowledgements . . . . . . . . . . . . . . . . . . . . 408 References . . . . . . . . . . . . . . . . . . . . . . . 408 * Corresponding author. E-mail: jpuntier@crub.uncoma.edu.ar 002+4074/99/080395 + 16 $30.00/0 395 0 1999 The Linnean Society of London Downloaded from https://academic.oup.com/botlinnean/article-abstract/130/4/395/2567145 by guest on 01 June 2020