carrot order of flowering plants, containing some 5,500 species. The main families in the order are Apiaceae (parsley family) and Araliaceae (ginseng family), which are closely related; some researchers advocate merging the two families into one expanded Apiaceae family. Both these families, in turn, are most closely related to Pittosporaceae, and several smaller families are also placed in this order. Apiales belongs to the core asterid clade (organisms with a single common ancestor), or sympetalous lineage of flowering plants, in the Asterid II group of the Angiosperm Phylogeny Group II (APG II) botanical classification system (see angiosperm).

Apiaceae, or the parsley family, contains some 434 genera and nearly 3,800 species. The family is distributed worldwide, though most species are concentrated in the northern temperate zone. Apiaceae includes a broad array of important foods, herbs, and spices, as well as some poisonous species. Most members are aromatic herbs with alternate compound or cleft leaves that are sheathed at the base. The flowers are often arranged in a conspicuous umbel (a flat-topped cluster of flowers). Each small flower is usually bisexual, with five small sepals, five generally clawed petals, an enlarged disk at the base of the style, and an inferior ovary with two carpels. The fruits are ridged and composed of two parts that split open at maturity. Among the species cultivated for food or spice are Anethum graveolens ( dill), Apium graveolens ( celery), Carum carvi ( caraway), Coriandrum sativum ( coriander, or cilantro), Cuminum cyminum ( cumin), Daucus carota ( carrot), Foeniculum vulgare ( fennel), Pastinaca sativa ( parsnip), Petroselinum crispum (parsley), and Pimpinella anisum ( anise). Other members are poisonous, including Cicuta maculata ( water hemlock) and Conium maculatum ( poison hemlock).

Araliaceae, or the ginseng family, contains 43 genera and about 1,450 species. The family is mostly native to tropical regions, with species concentrated in Southeast Asia and tropical North and South America, but important members native to temperate regions include Panax (ginseng), Hedera ( ivy), and Aralia ( spikenard). Most members of the family are shrubs or trees, though there are a number of climbers and a few herbs. The family has large, usually alternate, compound leaves, five-parted flowers arranged in compound umbels, and fruits that are generally fleshy (berries or drupes (drupe)). Some genera, such as the herbaceous Hydrocotyle (pennywort), were traditionally included in Apiaceae but have been placed in Araliaceae under the APG II system.

Several members of Araliaceae are economically important. Ivies are grown as ornamental plants and houseplants. Tetrapanax papyriferum (rice-paper plant) is the source of rice paper, and the wood of several species, especially that of Dendropanax arboreum, provides timber. Schefflera (650 species) is the largest genus in the family and includes tropical ornamental and potted plant species such as S. actinophylla (umbrella tree, or octopus plant) and S. elegantissima (false aralia). Polyscias is also a widely cultivated tropical tree, with many variegated forms.

Pittosporaceae has 9 genera and 200 species of trees, shrubs, and lianas native to tropical and warm temperate areas of the Old World, especially Australia. The largest genus is Pittosporum, with 140 species; some produce timber, but many are cultivated in warm climates as potted plants or street trees, such as P. tobira. Flowers of Pittosporaceae have a basally tubular corolla and well-developed sepals. The ovary is superior, with many ovules per carpel. Before its relationship to Araliales was recognized, the family was treated in the Cronquist system of botanical classification as part of Rosales. These three orders all have characteristic aromatic odours that are caused by triterpenoid ethereal oils, and some of them share a number of specialized chemical compounds, such as coumarins and polyacetylenes.