Comparative floral structure and systematics in Chrysobalanaceae s.l. (Chrysobalanaceae, Dichapetalaceae, Euphroniaceae, Trigoniaceae; Malpighiales)

Abstract

Chrysobalanaceae s.l., one of the few suprafamilial subclades of Malpighiales that is supported by molecular phylogenetic analyses, and containing Chrysobalanaceae, Dichapetalaceae, Euphroniaceae, and Trigoniaceae, was comparatively studied with regard to floral structure. The subclade is well supported by floral structure. Potential synapomorphies for Chrysobalanaceae s.l. are the following shared features: floral cup; flowers obliquely monosymmetric; sepals congenitally united at base; sepals of unequal size (outer two shorter); fertile stamens concentrated on the anterior side of the flower and sometimes united into a strap; staminodes absent in the posteriormost antepetalous position; anthers extremely introrse, with thecae almost in one plane; endothecium continuous over the dorsal side of the connective; dorsal anther pit; gynoecium completely syncarpous up to the stigma; carpel flanks slightly bulged out transversely and thus carpels demarcated from each other by a longitudinal furrow; flowers with dense unicellular, non-lignified hairs, especially on the gynoecium; light-coloured, dense indumentum on young shoots and inflorescences. Potential synapomorphies for Chrysobalanaceae + Euphroniaceae include: spur in floral cup; clawed petals; lignified hairs on petals; nectary without lobes or scales and mostly annular. Potential synapomorphies for Dichapetalaceae + Trigoniaceae include: special mucilage cells in sepals in mesophyll (in addition to epidermis); anthers almost basifixed; gynoecium synascidiate up to lower style; nectary with lobes or scales and semi-annular.

The Immense Diversity of Floral Monosymmetry and Asymmetry Across Angiosperms

“…In some rain-dispersed plants of otherwise polysymmetric groups (with disymmetric gynoecium) the fruits (and the gynoecium at anthesis) are pronouncedly monosymmetric, such as Tiarella and some Chrysosplenium species of Saxifragaceae. The same applies for some species of Begonia (Begoniaceae, Cucurbitales) (Matthews & Endress, 2004;Tebbitt et al, 2006). In Tiarella the gynoecium is horizontally exposed with two broad, shovel-shaped carpels.…”

“…In contrast, in monocots, molecular developmental studies in large monosymmetric groups to date concentrated more on aspects of floral organ identity than symmetry, such as in Poaceae (Malcomber & Kellogg, 2004;Whipple & Schmidt, 2006), Orchidaceae (Tsai et al, 2008;Mondragón-Palomino & Theissen, 2009;Mondragón-Palomino et al, 2009), or Zingiberales (Specht et al, 2008;. However, the present study does not especially focus on those large clades, but it aims to follow the occurrence of monosymmetry through all major angiosperm groups (orders and families; see also Endress, 2010Endress, , 2011.…”

“…Floral monosymmetry, although unusual, is not absent. It is mostly monosymmetry by simplicity, by the presence of only one carpel and/or only one stamen, such as in Hydatellaceae (Hamann, 1975;Saarela et al, 2007;Rudall et al, 2007), Trimeniaceae (Endress, 2001b), Chloranthaceae (Endress, 1987;Kong et al, 2002), Ceratophyllaceae (Endress, 2001b(Endress, , 2004, some Winteraceae (Igersheim & Endress, 1997), Piperaceae (Tucker, 1984;Tucker et al, 1993), Degeneriaceae, Myristicaceae (Igersheim & Endress, 1997), Lauraceae (Endress, 1972), and Hernandiaceae (Endress & Lorence, 2004). Among Annonaceae flowers with one carpel have evolved several times as shown by their distribution in the phylogenetic tree by Doyle et al (2004).…”

“…Floral symmetry, which has long fascinated botanists (Sprengel, 1793;de Candolle, 1813;Wydler, 1844), continues to attract different fields of research more than ever, such as (1) floral developmental genetics (Coen et al, 1995;Cubas et al, 1999b;Hileman et al, 2003;Busch & Zachgo, 2009;Jabbour et al, 2009b;Preston & Hileman, 2009;Zhang et al, 2010;Bartlett & Specht, 2011;Preston et al, 2011), (2) comparative morphology with a special focus on diversity (Endress, 1999(Endress, , 2001a(Endress, , 2006(Endress, , 2010(Endress, , 2011Tucker, 1999;Endress & Matthews, 2006), (3) pollination ecology (Dafni & Kevan, 1996;Neal et al, 1998;Giurfa et al, 1999;Lehrer, 1999;Jesson & Barrett, 2003;Kalisz et al, 2006), and (4) evolution (Donoghue et al, 1998;Ree & Donoghue, 1999;Citerne et al, 2010;Zhang et al, 2012). Monosymmetry and asymmetry are of special evolutionary significance.…”

BLOOMING PATTERN OF PASSION FRUIT FLOWER (<i>PASSIFLORA EDULIS</i> SIMS.) UNDER DIVERSIFIED FLASHES

“…There are three styles united at base and at the top of style there are three bifurcated stigmas (Matthews and Endress, 2008). It is protandrous as anther dehiscence before stigma becomes receptive which persists from time of flower blooming to withering.…”