Hamamelidales is an order of flowering plants formerly accepted in a number of systems of plant taxonomy, including the Cronquist system published in 1968 and 1988. The order is not currently accepted in the Angiosperm Phylogeny Group III system of plant taxonomy, the most widely accepted system as molecular systematic studies have suggested that these families are not closely related to each other. The APG II system (2003) assigns them to several different orders: Hamamelidaceae and Cercidiphyllaceae to Saxifragales, Eupteleaceae to Ranunculales, Platanaceae to Proteales, and Myrothamnaceae to Gunnerales. Additional studies of the chloroplast genome have since confirmed that the families moved into the Saxigragales are closely related.
Illiciales is an order of flowering plants that is not recognized by the current most widely used system of plant classification, the Angiosperm Phylogeny Group's APG III system. The order was comprised differently in various systems of plant taxonomy, but is composed of 2-4 families of shrubs, trees, and lianas native to Australasia, south eastern Asia, and the southeastern United States. The families all contain species with essential oils, and flowers with a perianth with bracts, sepals, and petals incompletely distinguished from each other and not arranged in definite whorls. The families of the order had been variably placed in other orders in different taxonomies.
Ceratophyllaceae is a cosmopolitan family of flowering plants including one living genus commonly found in ponds, marshes, and quiet streams in tropical and in temperate regions. It is the only extant family in the order Ceratophyllales. Species are commonly called coontails or hornworts, although hornwort is also used for unrelated plants of the division Anthocerotophyta.
The Aquifoliales are an order of flowering plants, including the Aquifoliaceae (holly) family, and also the Helwingiaceae and the Phyllonomaceae. In 2001, the families Stemonuraceae and Cardiopteridaceae were added to this order. This circumscription of Aquifoliales was recognized by the Angiosperm Phylogeny Group when they published the APG II system in 2003. In the Cronquist system, there is no Aquifoliales order: the Aquifoliaceae are placed within the order Celastrales and the others are in other families.
The Gunnerales are an order of flowering plants. In the APG III system (2009) and APG IV system (2016) it contains two genera: Gunnera and Myrothamnus. In the Cronquist system (1981), the Gunneraceae were in the Haloragales and Myrothamnaceae in the Hamamelidales. DNA analysis was definitive, but the grouping of the two families was a surprise, given their very dissimilar morphologies. In Cronquist's old system, and Takhtajan's (1997), the Gunneraceae were in the Rosidae, and the Myrothamnaceae were in the Hamamelids. In modern classification systems such as APG III and APG IV this order was the first to derive from the core eudicots.
The Xyridaceae are a family of flowering plants. This family has been recognized by many taxonomists and is known as the yellow-eyed grass family.
The Oxalidaceae, or wood sorrel family, are a small family of five genera of herbaceous plants, shrubs and small trees, with the great majority of the 570 species in the genus Oxalis. Members of this family typically have divided leaves, the leaflets showing "sleep movements", spreading open in light and closing in darkness.
Asphodelaceae is a family of flowering plants in the order Asparagales. Such a family has been recognized by most taxonomists, but the circumscription has varied widely. In its current circumscription in the APG IV system, it includes about 40 genera and 900 known species. The type genus is Asphodelus.
Trimeniaceae is a family of flowering plants recognized by most taxonomists, at least for the past several decades. It is a small family of one genus, Trimenia, with eight known species of woody plants, bearing essential oils. The family is subtropical to tropical and found in Southeast Asia, eastern Australia and on several Pacific Islands.
Euptelea is a genus of two species of flowering plants in the monogeneric family Eupteleaceae. The genus is found from Assam east through China to Japan, and consists of shrubs or small trees:
The Thurniaceae are a family of flowering plants composed of two genera with four species. The botanical name has been recognized by most taxonomists.
The Rapateaceae are a family of flowering plants. The botanical name has been recognized by most taxonomists.
The Muntingiaceae are a family of flowering plants, belonging to the rosid order Malvales. The family consists of three genera: Dicraspidia, Muntingia, and Neotessmannia, each with a single species. They are woody plants of the tropical regions of America. The older Cronquist system placed these genera in the family Tiliaceae, with which they share morphological similarities, but have no evolutionary affinity. Muntingia calabura is widely introduced in tropical regions, because of its edible fruit. Dicraspidia donnell-smithii and Neotessmannia uniflora are the other two species in the family, the latter only known from herbarium specimens.
Philesiaceae is a family of flowering plants, including two genera, each with a single species. The members of the family are woody shrubs or vines endemic to southern Chile.
Ixiolirion is a genus of flowering plants native to central and southwest Asia, first described as a genus in 1821. Recent classifications place the group in the monogeneric family Ixioliriaceae in the order Asparagales of the monocots. In earlier systems of classification, it was usually placed in the family Amaryllidaceae.
Tecophilaeaceae is a family of flowering plants, placed in the order Asparagales of the monocots. It consists of nine genera with a total of 27 species.
Kirkiaceae is a family of flowering plants in the order Sapindales. It comprises one genera, Kirkia, totalling six species. These two genera were previously placed in family Simaroubaceae, but were transferred into their own family because they produce neither quassinoids nor limonoids. Kirkia is named for Captain John Kirk (explorer) of the famous Zambesi Expedition.
The Paracryphiaceae are a family of woody shrubs and trees native to Australia, southeast Asia, and New Caledonia. In the APG III system of 2009, the family is placed in its own order, Paracryphiales, in the campanulid clade of the asterids. In the earlier APG II system, the family was unplaced as to order and included only Paracryphia.
Hydrostachys is a genus of about 22 species of flowering plants native to Madagascar and southern and central Africa. It is the only genus in the family Hydrostachyaceae. All species of Hydrostachys are aquatic, growing on rocks in fast-moving water. They have tuberous roots, usually pinnately compound leaves, and highly reduced flowers on dense spikes.
Huaceae is a family of plant in the rosids group, which has been classed in the orders Malpighiales, Malvales, and Violales or in its own order Huales. The APG II system placed it in the clade eurosids I, whereas the APG III system of 2009 and APG IV (2016) place it within the Oxalidales. The family is endemic to central Africa. It contains four species in the following two genera:
