XV lnternational A.P.L.E. Symposium of Palynolog

Hesse, M.

Repositorio Institucional de la Universidad de Córdoba

Abslracts XV A.P.L.E. Symposium Session: Pollen and Spore Morphology Gymnostachys, unlikeAcorus, should be retained within Araceae: pollen ultrastructure supports molecular results M. Hesse Department of Palynology and Structural Botan y, Institute of Botan y, University of Yienna, Rennweg 14, A 1030 Wien , Austria. E-mail : michael.hesse@ univie.ac.at Most of the aroid subfa milies clearly come out in the molecul ar trees (Barabé el al. 2004, Cabrera et al. 2003, Tarn el al. 2004). Gymnostachydoideae and Oronto ideae (clade 1 of Tarn et al. 2004, the ciad e consisting of the rnonogeneric subfam il y Gymnostachydoideae sister with subfamily Orontioideae, and occupying the basal position in the Araceae) constitute the majar group «proto-Araceae» sensu Mayo et al. 1997). They face all the other aro id subfarn il ies, the <<True Araceae» sensu Mayo et al . ( 1997). Ultrastructural palien wall characters confirm unequ ivocally the tribal arra ngement in the rnorpholog ical classifi cation by Mayo e t. al. ( 1997) and support greatly the arrangement oftri bes and genera in the molecu lar trees. In severa] cases, palien features are distinctive in clades corresponding to well circumscribed subfa mili es or in close ly related tribes within parts of subfamilies. This is valid especiall y for the Lasioideae, the Monsteroideae, the Zami ocu lcadoideae and the (gen uine) Aroideae wi th their unique combination of palien characters (Hesse 2002, Bogner & Hesse 2005). In sorne earlier classitications Gymnostachys together with Acorus formed a clade ora subfamily within Araceae, but at present Acorus is treated asan arder (Acora les) of its own. There is still a debate (Buzgo 200 l ) about Gymnostachys: either to be included (retained) within Araceae (as the most basal subfami ly with its single genus containing the most primiti ve characters, see Grayum 1990, Bogner & icolson 199 1, Mayo et al. 1997, all basing on anatomical-morphological characters, or French et al. 1995, Cabrera et al. 2003, Tam et al. 2004, both basing on molecul ar data), or to be excluded from Araceae (Hay & Mabberley 1 99 1, frorn anatomical-morphological reasons), a hypothesis al so by Josef Bogner (pers. comm.). We wondered if Gymnostachys palien features wou ld support a segregation from all the other Araceae, espec ia ll y from the other basal subfamily of proto-Araceae, the Orontioideae. In fac llhere is nota single pa lien feature which would support such a hypothesis. In contras!, a ll palien characters of Gymnostachys (Gym nostachydoideae) are in very good agreement and praclically identical with those of Orontium , Lysichiton and Symplocarpus (Orontioideae): a thick tectum, rather high columellae, a thin , often Jamellate endexi ne, and a stereotypicall y formed sul cus. Moreover, the Orontioideae differ pa lynolog ically clearly from the next subfamily, the Pothoideae, not to speak ofthe other aroid subfarnilies: distinctive features are the typically rather thin and open tectum, the presence of low colurnellae, and an often spongy endex ine (the respective foot layers do not show significan! differences). Vol. 16 (2006) 37 Abstracts XV A.P.L.E. Symposium Hence, the proto-Araceae (Gymnostachydoideae and Orontioideae) are palynologically clearly separated from the True Araceae (sen su Mayo et al. 1997), but 1ikewise clearly different from the formerly in Araceae included genus Acorus, which shows a prominent, widely closed tectum and a clearly different, unique apenure construction: a continuous endexine across the sulcus region anda secretory tapetum, wh ile in a11 Araceae a plasmodial tapetum seems to be present. In conclus ion, the p1acement of Gymnostachys by its pollen characters is in accordance with molecular results, and this is another fine example for the utility of palien characters as a compass needle for systematics. References: BARABÉ, D., LACROIX, C. , BRUNEAU, A., ARCHAMBAULT, A. & GIBERNAU, M. 2004. Floral development and phylogenetic position of Schismatoglottis (Araceae). lnt. J. Plant Sci. , 165(1): 173- 189. BOGNER, J. & HESSE, M. 2005. Zamioculcadoideae, a new subfamily of Araceae. Aroideana, 28: 3-20. BOGNER, J. & NICOLSON, D.H. 1991. A revised classification of Araceae with dichotomous keys. Wil/denowia, 21: 35-50. BUZGO, M. 200 l. Flower structure and deve1opment of Araceae compared with alismatids and Acoraceae. Bot. J. Linn. Soc. , 136: 393-425. CABRERA, L.l ., SALAZAR, G.A. , CHASE, M.W. & MAYO, S .J . 2003 . Phylogenetics of Araceae and Lemnaceae: evidence from multiple p1astid DNA data sets. Third lntemationa1 Conference on the Comparative Biology of the Monocotyledons, Ontario. California. Abstrae!, p. 11. FRENCH, J.C. , CHUNG, M.G. & HUR, Y.K. 1995. Chloroplast DNA phylogeny of the Ariflorae. In : P.J . Rudall , P.J . Cribb , D .P. Cutler, C. J. Humphries (eds) Monocoty1edons, Systematics and Evolution . Royal Botanic Gardens, Kew. pp. 255-275 . GRAYUM, M. H. 1990. Evo1ution and phylogeny of the Araceae. Ann. Missouri Bot. Gard., 77: 167-203 . HAY, A. & MABBERLEY, D.J. 1991. 'Transference of Function' and the origin of aroids: their significance in early angiosperm evolution. Bot. Jahrb. Syst., 113: 339-428. Hesse M. , 2002. The uniquely designed pollen apenure in Lasioideae (Araceae). Aroideana, 25: 51-59. MAYO, S.J., BOGNER, J. & BOYCE, P.C. 1997. The Genera of Araceae. RoyaL Botanic Gardens, Kew. TAM, S.M. , BOYCE, P.C. , UPSON, T.M. , BARABÉ, D. , BRUNEAU, A., FOREST, F. & PARKER, J.S . 2004 . lntergeneric and infrafamilial phylogeny of subfami ly Monsteroideae (Araceae) revealed by chloroplast trnL-F sequences. Am. J. Bot., 91: 490-498 . 38 Polen 

Gymnostachys, unlike Acorus, should be retained within Araceae: pollen ultrastructure supports molecular results

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