Comparative floral structure and systematics in Ochnaceaes.l.(Ochnaceae, Quiinaceae and Medusagynaceae; Malpighiales)

Abstract

Ochnaceae s.l. (Ochnaceae, Quiinaceae and Medusagynaceae), one of the well-supported subclades of the large order Malpighiales retrieved so far in molecular phylogenetic studies, were comparatively studied with regard to floral structure using microtome section series and scanning electron microscopy (SEM). Floral morphology, anatomy and histology also strongly reflect this close relationship. Potential synapomorphies of the subclade include: flowers nectarless, sepals of different sizes within a flower, petals not retarded in development and forming the protective organs of advanced floral buds, petal aestivation contort, petals with three vascular traces, petals reflexed over the sepals and directed toward the pedicel, polystemony, anthers almost or completely basifixed, gynoecium often with more than five carpels, short gynophore present, styles separate for at least their uppermost part and radiating outwards, suction-cup-shaped stigmas, vasculature forming a dorsal band of bundles in the upper stylar region, gynoecium epidermis with large, radially elongate cells, ovules either weakly crassinucellar or incompletely tenuinucellar with an endothelium, abundance of tanniferous tissues and sclerenchyma in floral organs. The most strongly supported subclade of two of the three families in molecular analyses, Quiinaceae and Medusagynaceae, is also particularly well supported by floral structural features, including the presence of functionally and morphologically unisexual flowers, a massive thecal septum that persists after anther dehiscence, styles radiating outward from the ovary, two lateral ovules per carpel, positioned one above the other, conspicuous longitudinal ribs on the ovary wall at anthesis, and a 'false endothelium' on the nucellus at anthesis. Additionally, the group fits well in Malpighiales and further emphasizes the relationship of Malpighiales with Celastrales and Oxalidales, and thus the unity of the COM clade.

Comparative floral structure and systematics of the clade of Lophopyxidaceae and Putranjivaceae (Malpighiales)

“… Micropyle present. Nectary lobes (when present) alternating with the (outer) sepals. Pedicel articulation weak or lacking (in contrast with many other Malpighiales; Stevens, onwards; Matthews & Endress, , ; Matthews et al ., ). Fruit indehiscent. Mucilage cells and special mucilage cells (as defined by Matthews & Endress, ) absent in floral organs.…”

“…For Malpighiales, we began with Chrysobalanaceae and relatives (five families; Merino Sutter & Endress, ; Matthews & Endress, ), followed by Rhizophoraceae and potentially related families (seven families; Matthews & Endress, ), and Ochnaceae s.l. (three previously recognized families; Matthews, Amaral & Endress, ). In addition, we presented a survey of the current knowledge of floral structure across Malpighiales (Endress, Davis & Matthews, ).…”

The emergence of core eudicots: new floral evidence from the earliest Late Cretaceous

“…In the N-fixing clade, a floral cup is present in certain Rosales [40,41] and Cucurbitales [31], while in the COM clade, it occurs in Celastrales [32], Oxalidales [30] and Malpighiales [29,35–37,46]. Among malvids, a floral cup occurs in certain Brassicales [47], Huerteales [28] and Sapindales [48,49].…”

<I>Sauvagesia paganuccii</I> (Ochnaceae), a New Species Endemic to Campo Rupestre Vegetation of Bahia, Brazil

“…The genus Sauvagesia L. (Ochnaceae) is traditionally characterized by pentamerous, usually actinomorphic flowers with pink to whitish flowers, five stamens, and one or two whorl of staminodes (Sastre 1997;Matthews et al 2012). The arrangement of the staminodes was used by Sastre (1981) to define the two subsections of section Sauvagesia.…”

“…Subsection Vellozianae Sastre, where the new species reported here is most morphologically similar to, can be recognized by the internal whorl with the staminodes united, to form a corona-like tube, while the other subsection, Sauvagesia, has the internal whorl with the staminodes free. The tube of staminodes enveloping the stamens and gynoecium has been reported as an unusual special elaboration or transference of function for buzzpollination (Kubitzki and Amaral 1991;Nadia and Machado 2005;Matthews et al 2012). A molecular phylogenetic analysis of nuclear and plastid DNA sequences that has sampled thoroughly within Ochnaceae (Schneider et al 2014) has not supported the monophyly of Sauvagesia, however the sampling within the genus is limited to only four species.…”