Saxifragales are found worldwide, primarily in temperate to subtropical zones, rarely being encountered growing wild in the tropics; however, many species are now cultivated throughout the world as knowledge of plant husbandry has improved.

Many are epiphytic or lithophytic, growing on exposed cliff faces, on trees or on rocks, and not requiring a highly organic or nutrient-dense substrate to thrive.

Several families—such as the aforementioned Crassulaceae—and genera are of significant commercial importance in some countries and economies, being cultivated on a large scale for sale as ornamental plants.

Overall, the order is extremely diverse, encompassing numerous trees, shrubs, perennial herbs and succulent plants, as well as aquatic and semi-aquatic species.

The order's high degree of diversity, in terms of vegetative and reproductive traits (and sheer amount of species), can make it challenging to find any common or unifying features amongst the respective genera.

It includes trees (e.g. witch hazel, witch alder in Hamamelidaceae), fruit bearing shrubs (e.g. currants, gooseberries in Grossulariaceae), lianas, annual and perennial herbs, rock garden plants (e.g. saxifrage in Saxifragaceae), ornamental garden plants (e.g. peonies in Paeoniaceae), succulents (e.g. stonecrop in Crassulaceae) and aquatics (e.g. watermilfoil in Haloragaceae).

[2] The flowers demonstrate major variations in sepal, petal, stamen, and carpel number, as well as ovary position (see Biogeography and evolution).

[3] Saxifragales was first described in 1820 by Berchtold and Presl as a group of plants, Saxifrageae, with five genera, including Saxifraga, lending their names as the botanical authority (Bercht.

[11] The order Saxifragales has undergone considerable revision in both placement and composition, since the use of molecular phylogenetics, and the use of the modern Angiosperm Phylogeny Group (APG) classification.

The core eudicots consist of the order Gunnerales and a large clade of Pentapetalae (so named for having a synapomorphy of pentamerous (5 part) perianths), the latter representing about 70% of all angiosperms, with eight major lineages.

[14][15] Later (2003), the order was described as "one of the major surprises of molecular phylogenetic analyses of the angiosperms", having elements previously placed in three or four separate subclasses based on morphology.

[16][3] This was eventually resolved in the third APG system (2009), placing Saxifragales as a sister group to the rosids (Rosidae), within the Pentapetalae clade.

A number of independent transitions to a herbaceous habit occurred in the ancestors of Crassulaceae, Saxifragaceae and the base of the Haloragaceae-Penthoraceae clade (the other two families in Haloragaceae s.l.

Most of Saxifragales have a superior ovary, but some families show frequent transition with inferior or subinferior position, particularly Saxifragaceae and to a lesser extent Hamamelidaceae.

[34] Within this, APG II (2003) proposed placing the two species of Pterostemon that constitute Pterostemonaceae within Iteaceae, and all subsequent versions have maintained this practice.

The APG II system placed the family in Malpighiales, based on a DNA sequence for the rbcL gene from Whittonia.

[44] Daphniphyllum was always thought to have an anomalous combination of characters[45][45] and was placed in several different orders before molecular phylogenetic analysis showed it to belong to Saxifragales.

[6][61][21] The Hamamelidaceae (Witch-hazel family) consists of trees and shrubs with a widespread distribution, but main centres in East Asia and Malaysia.

The species have uses as medicaments, timber and ornamental plants for their flowers, such as Hamamelis (witch hazel) or leaves, such as Parrotia persica (Persian ironwood).

The name is derived from the Greek words dafne (laurel) and fyllon (leaf), from a supposed resemblance to the leaves of the former (Laurus nobilis).

[61][21][6] The Aphanopetalaceae (Gum-vine family) consists of a single genus of Australian climbing shrubs, Aphanopetalum, which has two species, A. clematidium (SW Australia) and A. resinosum (Queensland, NSW).

The major horticultural genus is Myriophyllum (watermilfoil) whose species are valued as aquaria and pond plants but may escape and naturalise, becoming invasive.

is more widespread, from the Himalayas to Japan and western Malesia and one species in eastern N America (I. virginica) whereas Pterostemon (c. 2 spp) is confined to Oaxaca, Mexico.

The single genus, Ribes, has about 150 species that are commercially important and widely cultivated for their fruit and also grown as ornamentals, such as R. uva-crispa (gooseberry) and R. nigrum (blackcurrant).

The family, greatly reduced, includes 35 genera and about 640 species, in two lineages, saxifragoids (e.g. Saxifraga, rockfoil) and heucheroids (e.g. Heuchera, coral bells).

They provide foodstuffs and medicaments and include many ornamentals, particularly of border, rock and woodland gardens, such as Astilbe, though the largest number of cultivated species belong to Saxifraga.

Among the most threatened Saxifragales are Aichryson dumosum and Monanthes wildpretii (Crassulaceae), Haloragis stokesii and Myriophyllum axilliflorum (Haloragaceae), Ribes malvifolium and R. sardoum (Grossulariaceae), Saxifraga artvinensis (Saxifragaceae) and Molinadendron hondurense (Hamamelidaceae).

[61] Paeonia are cultivated both as ornamental shrubs (generally sold as root stock) and for cut flowers, with the Netherlands representing the largest production, other more minor producers are Israel, New Zealand, Chile and the United States.

R. nigrum is the most important commercial currant crop, being produced in more than 23 countries, with the major centres being Russia (more than 63 thousand hectares), Poland, Germany, Scandinavia and the UK.

[73] An important source of Vitamin C, black currants are used in the manufacture of jam, fruit jelly, compote, syrup, juice and other drinks, including the cordial Ribena and the liqueur Cassis.