[3] In the APG III system of classification of flowering plants, Ochnaceae is defined broadly, to include about 550 species,[4] and encompasses what some taxonomists have treated as the separate families Medusagynaceae and Quiinaceae.

Venation often scalariform (ladder-like) in appearance, with parallel and closely spaced secondary and tertiary veins.

Anthers basifixed or slightly dorsifixed, usually dehiscing by one or two apical or subapical pores, sometimes latrorsely by longitudinal slits.

Fruit sometimes winged; rarely a nut or drupe, often berry-like; usually a septicidal capsule, or else the ovary separating to form blackish drupelets on a usually reddish, accrescent receptacle.

Until near the end of the 20th century, Ochnaceae was regarded as a rather odd family, difficult to place with a high degree of certainty.

Even into the 21st century, some authors treated the genus Strasburgeria as the closest relative of Ochnaceae, and some even placed it within the family.

[22] In the APG III system, Strasburgeria is grouped with Ixerba to form the family Strasburgeriaceae in the rosid order Crossosomatales.

Molecular phylogenetic studies have strongly supported the inclusion of Diegodendron in the rosid order Malvales, and it is sometimes treated as a monospecific family therein.

All had been placed, at one time or another, with Ochnaceae, near Theaceae, a family now included in the basal asterid order Ericales.

The clusioids were once regarded as a group of four families,[25] but Clusiaceae was divided in 2009[7] and the name Calophyllaceae was resurrected for one of the resulting segregates.

[5] A molecular phylogenetic study resolved Medusagynoideae and Quiinoideae as sister subfamilies, but this result had only weak statistical support.

An additional genus, Neckia, was resurrected in that same year, based on the results of a molecular phylogenetic study.

It produces an unusual fruit, in which two of the sepals become greatly enlarged and form wings that facilitate seed distribution by wind.

All of the genera in Ochneae appear to be monophyletic, as defined by Amaral and Bittrich (2014), but in one molecular phylogenetic study, Ouratea and Ochna received only weak bootstrap support in the maximum likelihood analysis.

Medusagyne Froesia Quiina Lacunaria Touroulia Testulea Luxemburgia Philacra Lophira Elvasia Perissocarpa Campylospermum Ochna Ouratea Rhabdophyllum Brackenridgea Idertia Blastemanthus Godoya Rhytidanthera Cespedesia Krukoviella Fleurydora Poecilandra Wallacea Neckia Schuurmansia Euthemis Schuurmansiella Tyleria Adenarake Indosinia Sauvagesia The evolution of Ochnaceae has been unusual in that it has included two complete reversions to an actinomorphic floral symmetry and two nearly complete reversions to apocarpy, a condition in which the carpels are entirely separate.

In the subtribe Ochninae, and in the genus Froesia, the components of the ovary (carpels) are very shortly united at the base.

In the genera Froesia and Quiina, and in the tribe Ochneae, the endosperm is completely absorbed early in seed development.

In Testulea and in a clade of four genera in Sauvagesieae (Godoya, Rhytidanthera, Krukoviella, and Cespedesia), the number of ovules is 100 to 200 per carpel.

[citation needed] Gomphia has long been a source of confusion[36] and it was not recognized in the most recent revision of Ochnaceae.

[38] De Candolle believed that Simaroubaceae was closely related to Ochnaceae, but it is now placed in the order Sapindales.

In 1874, Engler divided Ochnaceae into two groups, based on the absence or presence of endosperm in the mature seed.

[39] The group without endosperm corresponds to de Candolle's concept of Ochnaceae, and to the modern tribe Ochneae.

The genera Quiina and Touroulia had been known since 1775, when they were described by Jean Baptiste Aublet,[41] and they were variously classified by 19th century taxonomists.

Jacques Denys Choisy erected the family Quiinaceae (as Quiinacées) for them in 1849,[42] but he did not meet the requirements for valid publication of a botanical name.

[33][43] The genus Medusagyne had been described by John Gilbert Baker in 1877, in a flora of Mauritius and the Seychelles,[44] but it was not until 1924 that it was segregated into its own monogeneric family.

In 1925, for the second edition of DNP, Engler and Gilg expanded on their treatment of Quiinaceae and Ochnaceae, respectively, compared to what they had written in 1893.

In that same volume, Gilg divided his Ochnaceae (equivalent to modern Ochnoideae) into 21 genera, including Indovethia, Leitgebia, Vausagesia, and Lauradia (as Lavradia), which are now regarded as synonyms of Sauvagesia.

[4] Eight of the modern genera, (Philacra, Krukoviella, Fleurydora, Tyleria, Adenarake, Indosinia, Perissocarpa, and Idertia) consist of plants that had not been uncovered by botanical exploration at that time.

[4] In 1968, Andrias Kanis published a paper that greatly influenced subsequent work in Ochnaceae, right up to the 2014 revision.

[53] In that same year, Neckia, a 28th genus for Ochnoideae, was resurrected in a molecular phylogenetic study based on four chloroplast DNA loci, and nuclear ribosomal ITS.