Staedler, Y M; Endress, P K (2009). Diversity and lability of floral phyllotaxis in the pluricarpellate families of core Laurales (Gomortegaceae, Atherospermataceae, Siparunaceae, Monimiaceae). International Journal of Plant Sciences, 170(4):522-550. Postprint available at: http://www.zora.uzh.ch University of Zurich Posted at the Zurich Open Repository and Archive, University of Zurich. Zurich Open Repository and Archive http://www.zora.uzh.ch Originally published at: International Journal of Plant Sciences 2009, 170(4):522-550. Winterthurerstr. 190 CH-8057 Zurich http://www.zora.uzh.ch Year: 2009 Diversity and lability of floral phyllotaxis in the pluricarpellate families of core Laurales (Gomortegaceae, Atherospermataceae, Siparunaceae, Monimiaceae) Staedler, Y M; Endress, P K Staedler, Y M; Endress, P K (2009). Diversity and lability of floral phyllotaxis in the pluricarpellate families of core Laurales (Gomortegaceae, Atherospermataceae, Siparunaceae, Monimiaceae). International Journal of Plant Sciences, 170(4):522-550. Postprint available at: http://www.zora.uzh.ch Posted at the Zurich Open Repository and Archive, University of Zurich. http://www.zora.uzh.ch Originally published at: International Journal of Plant Sciences 2009, 170(4):522-550. Diversity and lability of floral phyllotaxis in the pluricarpellate families of core Laurales (Gomortegaceae, Atherospermataceae, Siparunaceae, Monimiaceae) Abstract Floral phyllotaxis of Laurales (Magnoliidae) is poorly and sometimes conflictingly documented, especially in the pluricarpellate families of the core Laurales (Gomortegaceae, Atherospermataceae, Siparunaceae, Monimiaceae). In this study four types of floral phyllotaxis were recovered: Fibonacci spiral, simple-whorled (decussate), complex-whorled, and irregular. Whorled and spiral phyllotaxis co‐occur in all families except Gomortegaceae and even vary within a species in some Mollinedioideae (Monimiaceae). Complex‐whorled floral phyllotaxis with two or more organs in a position where only one is expected and changes in merism are especially prominent in Atherospermataceae and Monimiaceae. The most elaborate complex‐whorled phyllotaxis pattern (leading to 8‐merous whorls) is present in flowers with a flat floral base. Presence of a hyperstigma is correlated with double positions in the perianth. Flowers with low organ number commonly have simple‐whorled phyllotaxis; flowers with high organ number have complex‐whorled or irregular patterns. Spiral phyllotaxis occurs in flowers with a broad range of organ numbers. Irregularities in organ sequence were found at the periphery of the gynoecium in some Atherospermataceae and Monimiaceae, involving staminodes, carpellodes, and carpels. In Laurales, floral phyllotaxis diversity appears to have evolved from spiral phyllotaxis, independently in Atherospermataceae, Siparunaceae, and Monimiaceae. Int. J. Plant Sci. 170(4):522–550. 2009. Ó 2009 by The University of Chicago. All rights reserved. 1058-5893/2009/17004-0008$15.00 DOI: 10.1086/597272 DIVERSITY AND LABILITY OF FLORAL PHYLLOTAXIS IN THE PLURICARPELLATE FAMILIES OF CORE LAURALES (GOMORTEGACEAE, ATHEROSPERMATACEAE, SIPARUNACEAE, MONIMIACEAE) Yannick M. Staedler1 and Peter K. Endress Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland Floral phyllotaxis of Laurales (Magnoliidae) is poorly and sometimes conflictingly documented, especially in the pluricarpellate families of the core Laurales (Gomortegaceae, Atherospermataceae, Siparunaceae, Monimiaceae). In this study four types of floral phyllotaxis were recovered: Fibonacci spiral, simple-whorled (decussate), complex- whorled, and irregular.Whorled and spiral phyllotaxis co-occur in all families except Gomortegaceae and even vary within a species in some Mollinedioideae (Monimiaceae). Complex-whorled floral phyllotaxis with two or more organs in a position where only one is expected and changes in merism are especially prominent in Athero- spermataceae and Monimiaceae. The most elaborate complex-whorled phyllotaxis pattern (leading to 8-merous whorls) is present in flowers with a flat floral base. Presence of a hyperstigma is correlated with double positions in the perianth. Flowers with low organ number commonly have simple-whorled phyllotaxis; flowers with high organ number have complex-whorled or irregular patterns. Spiral phyllotaxis occurs in flowers with a broad range of organ numbers. Irregularities in organ sequence were found at the periphery of the gynoecium in some Atherospermataceae and Monimiaceae, involving staminodes, carpellodes, and carpels. In Laurales, floral phyllotaxis diversity appears to have evolved from spiral phyllotaxis, independently in Atherospermataceae, Siparunaceae, and Monimiaceae. Keywords: floral phyllotaxis, Atherospermataceae, Gomortegaceae, Monimiaceae, Siparunaceae, Laurales. Introduction Laurales consist of two subclades of three families each (Ren- ner 2004): the clade containing Siparunaceae (53 species; Ren- It has long been assumed that one of the general trends in ner and Hausner 2005), Atherospermataceae (16 species; angiosperm evolution is the evolution of whorled flowers from Renner et al. 2000), and Gomortegaceae (one species; Kubitzki spiral ones (e.g., Takhtajan 1969; Kubitzki 1987; Cronquist 1993a) and the clade containing Monimiaceae (;270 species; 1988). This view was modified by Endress (1987) who, from Philipson 1993), Hernandiaceae (;60 species; Kubitzki 1969, the complex distribution of spiral and whorled flowers, hy- 1993b), and Lauraceae (2500–3500 species; Rohwer 1993). Si- pothesized that spiral and whorled flowers coexisted in basal parunaceae are sister to Atherospermataceae plus Gomortega- angiosperms and that the trend is not from spiral to whorled ceae (Renner 2004). Either Monimiaceae have an unsettled but from lability between spiral and whorled to stabilization position as sister to Lauraceae (Renner 1999, 2004), sister to of whorled patterns. Whorled phyllotaxis allows synorganiza- Hernandiaceae (Qiu et al. 1999, 2006), or sister to a clade com- tion and thus has a greater evolutionary potential than spiral prising Hernandiaceae and Lauraceae (Doyle and Endress phyllotaxis (Endress 1987, 2006). Phylogenetic studies indi- 2000; Chanderbali et al. 2001; Hilu et al. 2003) or the position cate that in basal angiosperms the evolutionary transition from of Hernandiaceae, Lauraceae, and Monimiaceae is unresolved a spiral to a whorled phyllotaxis or vice versa has occurred (Renner and Chanderbali 2000; Soltis et al. 2007). Monimia- several times in the perianth and androecium (Endress and ceae are divided into two subfamilies, Monimioideae (Peumus, Doyle 2007, 2009; see also Ronse De Craene et al. 2003; Za- Palmeria,andMonimia) and Mollinedioideae (all other genera; nis et al. 2003 [perianth only]). Such transitions are, however, Renner 2004), with Hortonia as the basalmost genus. poorly understood. One of the groups in which such transi- Flowers of Laurales commonly have a floral cup (with the tions took place is the Laurales (Ronse De Craene et al. 2003; exception of some Lauraceae; Rohwer 1993). Unisexual flow- Zanis et al. 2003; Endress and Doyle 2007, 2009). ers are common; in the pluricarpellate core Laurales, only a Laurales (Magnoliidae sensu Cantino et al. 2007) comprise few taxa have hermaphroditic flowers (Gomortegaceae, Daph- seven families. Calycanthaceae (nine species; Zhou et al. 2006) nandra, Doryphora, and Dryadodaphne of Atherospermata- are sister to the rest of the order, the core Laurales (Renner ceae and Hortonia of Monimiaceae). 1998, 1999, 2004; Qiu et al. 1999, 2005; fig. 1). The core In Calycanthaceae, floral phyllotaxis is uniformly spiral in the Fibonacci mode (Staedler et al. 2007). In contrast, in uni- carpellate families of core Laurales, spiral floral phyllotaxis is 1 Author for correspondence; e-mail: [email protected]. unknown; whorled patterns are predominant (Hernandiaceae Manuscript received September 2008; revised manuscript received December [Kubitzki 1969; Endress and Lorence 2004], Lauraceae [Mez 2008. 1889; Singh and Singh 1985; Hyland 1989; Rohwer 1993; 522 STAEDLER & ENDRESS—FLORAL PHYLLOTAXIS IN CORE LAURALES 523 In Monimioideae, floral phyllotaxis is not known in detail (but from preliminary observations was assumed to be spiral in the perianth by Doyle and Endress [2000] and Endress and Doyle [2009]). In Mollinedioideae it is documented for whole flowers only in very few taxa. Hortonia has a Fibonacci spiral pattern (Endress 1980a). Hedycarya arborea has a whorled perianth, but stamen phyllotaxis is spiral or irregular, carpellodes are whorled, and carpels are spiral (Sampson 1969a). For most spe- cies studied, data are limited to the perianth, which is often de- cussate, such as in species of Austromatthaea, Kairoa, Kibara, Mollinedia, Steganthera, Tambourissa, and Wilkiea (Endress 1979b, 1980b; Philipson 1980, 1985). Thus, from the litera- ture, floral phyllotaxis in Atherospermataceae and Monimia- ceae appears unusually diverse and unstable. The present work is a comparative study of floral phyllo- taxis in all four pluricarpellate families of the core Laurales. A number of taxa are studied for the first time, with the aim of resolving inconsistencies in earlier descriptions. Patterns and conditions of the unusual diversity and variability of floral phyllotaxis in the core Laurales are explored, such as different organ numbers, floral structure (shape, presence of hyperstigma), and gender in unisexual flowers (figs. 2–22). Finally,