The inflorescence: Introduction

Processes responsible of the structural diversity of the Cyperaceae synflorescence: Hypothetical evolutionary trends

“…Endl). Lengthening of internodes is related to the time of development of each species (Tucker and Grimes, 1999); it is genetically determined and can be mapped in a cladogram (Kellogg, 2000). Length reduction of the internodes of Pc of different order, as well as the reduction of the number of Pc and branching degree, the inhibition of the development of the short or long Pc in the UIF (Processes 16-19), is generally correlated with the reduction in number and shape of the bracts.…”

“…Because of the pivotal role of the inflorescence structure in the diversification of many taxa, and its significant value for phylogenetical analyses, it appears appropriate to consider the inflorescences from a new viewpoint (Tucker and Grimes, 1999). In this context, the typology-based system developed by Troll (1964) and Weberling (1989) has proved to be useful to describe inflorescences (Mora Osejo, 1987;Rua, 1999) as well as to indicate traits of considerable phylogenetic and evolutive value (Aagesen, 1999;Liu et al, 2005;Nickol, 1995;Rua and Aliscioni, 2002;Tortosa et al, 2004;Urdampilleta et al, 2005).…”

Open and closed inflorescences: more than simple opposites

“…The Gerbera and Zea examples unmask a latent terminological inconsistence: the term 'open inflorescences' is in morphology synonymized with 'indeterminate inflorescences' (Troll, 1964;Stebbins, 1974;Weberling, 1992;Coen and Nugent, 1994;Tucker, 1999;Prenner et al, 2009); and, as shown above, indeterminate inflorescences can arise from a developmentally determinate IM. In other words, the concept of 'determinate meristem', that refers to the existence of specific ontogenetic termination pathways (Bäurle and Laux, 2003;Teeri et al, 2006;Sablowski, 2007) and/or to a predictable and limited origin of parts (Vollbrecht, 2005;Bortiri and Hake, 2007;Barazesh and McSteen, 2008), is properly applicable to flower meristems (Angenent et al, 2005;Teeri et al, 2006;Sablowski, 2007;Kwiatkowska, 2008; but see Chiurugwi et al, 2007) and, analogously, to IMs that are topped by terminal flowers.…”

“…This notion was introduced in the seminal work of Gregoire (1938), who stressed that the reproductive transition produced an enlargement of the SAM along with the appearance of a homogenized deep-staining meristematic coat ('manchon meristematique') that provides a 'mantle-core' (MC) configuration to the meristem (Nougarède, 1967;Gifford and Corson, 1971;Buvat, 1989;Tucker, 1999;Kwiatkowska, 2008). Examples of histological transitions that endorse this proposition have been repeatedly described in closed, or 'monotelic' inflorescences (Troll, 1964;Weberling, 1992) belonging to Rosaceae (Grégoire, 1938;Rauh and Reznik, 1951;Phelouzat, 1963), Papaveraceae (Bersillon, 1955), and Ranunculaceae (Grégoire, 1938).…”

“…When the second step is fulfilled, a terminal flower is formed and the inflorescence is considered to be 'determinate' (Troll, 1964;Stebbins, 1974;Weberling, 1992;Coen and Nugent, 1994;Tucker 1999;Prenner et al, 2009). In the model plant Arabidopsis, that does not form terminal flowers in its wild-type inflorescences, the gene product TERMINAL FLOWER LOCUS 1 (TFL1) acts as an antagonist to the FM identity genes at the distal part of the SAM, guaranteeing the maintenance of IM identity and thus the 'indeterminate' character of the inflorescence (Shannon and Meeks-Wagner, 1991;Alvarez et al, 1992;Parcy et al, 2002;Penin et al, 2005;Bennloch et al, 2007;Sablowski, 2007;Argiriou et al, 2008;Wang and Li, 2008) (Fig.…”