Comparative floral structure and systematics in Celastrales (Celastraceae, Parnassiaceae, Lepidobotryaceae)

Abstract

Floral morphology, anatomy and histology in the newly circumscribed order Celastrales, comprising Celastraceae, Parnassiaceae and Lepidobotryaceae are studied comparatively. Several genera of Celastraceae and Lepidobotrys (Lepidobotryaceae) were studied for the first time in this respect. Celastraceae are well supported as a group by floral structure (including genera that were in separate families in earlier classifications); they have dorsally bulged-up locules (and thus apical septa) and contain oxalate druses in their floral tissues. The group of Celastraceae and Parnassiaceae is also well supported. They share completely syncarpous gynoecia with commissural stigmatic lobes (and strong concomitant development of the commissural vascular bundles but weak median carpel bundles), only weakly crassinucellar or incompletely tenuinucellar ovules with an endothelium, partly fringed sepals and petals, protandry in bisexual flowers combined with herkogamy by the movement of stamens and anther abscission, and stamens fused with the ovary. In contrast, Lepidobotryaceae are more distant from the other two families, sharing only a handful of features with Celastraceae (not Parnassiaceae), such as pseudohermaphroditic flowers, united stamen bases forming a collar around the gynoecium and seeds with a conspicuous aril. However, all three families together are also somewhat supported as a group and share petals that are not retarded in late floral bud development, 3-carpellate gynoecia, ventral slits of carpels closed by long interlocking epidermal cells and pollen tube transmitting tissue encompassing several cell layers, both integuments usually more than two cell layers thick, and only weak or lacking floral indumentum. In some molecular analyses Celastrales form an unsupported clade with Malpighiales and Oxalidales. This association is supported by floral structure, especially between Celastrales and Malpighiales. Among Celastrales, Lepidobotryaceae especially share special features with Malpighiales, including a diplostemonous androecium with ten fertile stamens, epitropous ovules with an obturator and strong vascularization around the chalaza.

Phylogeny and Delimitation of the Celastrales Inferred from Nuclear and Plastid Genes

“…Davis and Wurdack 2004), all except the last of which provided only weak branch support. However, it is consistent with Matthews and Endress' (2005) description of many morphological features that are shared between Celastrales and Malpighiales to the exclusion of Oxalidales, with only two potential morphological synapomorphies for Celastrales and Oxalidales.…”

“…Nicobariodendron is morphologically peculiar relative to other Celastraceae with its racemose inflorescences, unisexual flowers on dioecious plants, and two stamens (although none of these characteristics are unique to Nicobariodendron within the family). For a description of more typical morphological characteristics of the Celastraceae see Simmons (2004a) and Matthews and Endress (2005).…”

Comparative floral structure and development of Nitrariaceae (Sapindales) and systematic implications

“…However, because such comparative studies are time-consuming and the systematic classifi cation has diff erent hierarchical levels, they can only be done in a stepwise fashion (for eudicots, e.g. Matthews and Endress, 2002, 2005a, b , 2006von Balthazar et al, 2004 ;Sch ö nenberger and Grenhagen, 2005 ;Endress and Matthews, 2006 ;Ronse De Craene and Haston, 2006 ;von Balthazar et al, 2006 ;Endress, 2008 , 2009 ;Janka et al, 2008 ;Sch ö nenberger, 2009 ;von Balthazar and Sch ö nenberger, 2009 ;Sch ö nenberger et al, 2010 ).…”

The structure and mechanism of fruit dehiscence of some representatives of the Hippocrateoideae and Lophopetaleae (Celastraceae R. Br.)

“…У Hippocrateoideae плод развивается из олигомер-ного синкарпного гинецея, образованного сра-станием 3 (редко 2 или 5) плодолистиков. Синас-цидиатная зона выражена в базальной части ги-нецея (на примере Hippocratea barbata: Matthews, Endress, 2005). В области завязи наблюдаются 3 (редко 2 или 5) гнезда, с 2-10 семязачатками в каждом гнезде (нередко сидят в два ряда).…”