Ericales
Ericales is an order of plants that tend to grow in poor or acid soils. They have a tendency to symbiosis with mycorrhizae, sometimes they lose chlorophyll (Monotropa). Hermaphroditic flowers, generally actinomorphic; sympetalous corollas (except Clethraceae, with four free petals, forms a bridge with Theales); androecium with 2 free whorls of the corolla, soldered to a disk of the receptacle; poricidal anthers, with a tendency to form horns in the basal part; pollen release in tetrads (except Clethraceae); mainly entomophilous (sometimes anemophilous). Superior gynoecium, with partially closed carpels, parietal central placentation.
Ericales contains 22 families, 346 genera, and more than 12,000 species. Most members have at least loosely fused petals and radially symmetrical flowers, a 3-5-lobed superior ovary, and 5-10 (sometimes more) stamens often borne free from the petals. The fruit is usually a capsule and the seed coat is usually thin. Iridoids, distinctive chemicals that may be involved in protecting the plant from herbivores, are scattered throughout the order.
Classification
They belong to the Eudicotyledoneae clade of the APG III system. The following are typical families of recent classifications.
- Actinidiaceae (kiwi family)
- Balsaminaceae
- Clethraceae
- Cyrillaceae
- Diapensiaceae
- Ebenaceae
- Ericaceae
- Fouquieriaceae
- Lecythidaceae
- Marcgraviaceae
- Mitrastemonaceae
- Myrsinaceae
- Pellicieraceae
- Pentaphylacaceae
- Polemoniaceae
- Primulaceae
- Roridulaceae
- Sapotaceae (family of sapodilla or gum)
- Sarraceniaceae
- Sladeniaceae
- Styracaceae
- Symplocaceae
- Ternstroemiaceae
- Tetrameristaceae
- Theaceae (family of tea)
- Theophrastaceae
These make up the basal group of asterids. In Cronquist's system, the Ericales include a minor group of plants, placed among the Dilleniidae:
- Ericaceae
- Cyrillaceae
- Clethraceae
- Grubbiaceae
- Empetraceae
- Epacridaceae
- Pyrolaceae
- Monotropaceae
Economic importance
The most commercially used plant in the order is tea (Camellia sinensis) of the Theaceae family. The order also includes some edible fruits, including kiwi (esp. Actinidia deliciosa), persimmon (genus Diospyros), blueberry, Brazil nut, and mamey. The order also includes shea (Vitellaria paradoxa), which is the main source of lipids in the diet of millions of sub-Saharan Africans. Many species of Ericales are grown for their showy flowers: well-known examples are azalea, rhododendron, camellia, heather, polyanthus, cyclamen, phlox, and joy of home.
Ericaceae
Cosmopolitan family, more abundant in temperate and cold zones (in the tropics they are only present in the mountains). It comprises about 3000 species, adapted to poor and acid soils through symbiosis with mycorrhizae. Includes trees, shrubs or bushes, woody and generally fruitful.
Balsaminaceae
Balsams are annual or perennial herbaceous plants with translucent fleshy tissue on the stems. The plant parts are mostly bare. The alternate and spiral or mostly opposite, rarely arranged in whorls of three leaves, are simple and stalked. Teeth or bumps often form on the stem and leaf edge, which can secrete nectar (extrafloral nectaries). The leaf margin is smooth or often finely and sharply toothed. Stipulations generally cannot be observed.
Highly zygomorphic, quintuple, and hermaphroditic flowers rotated 180 degrees are characteristic. Of the three to five sepals, the middle one is greatly enlarged, mostly stimulated, and similar in color to the petals. In many species the spur is rounded and sac-shaped. Of the other four sepals, two are well developed, the last two often minute or absent. One of the five petals (rarely four) is enlarged and forms the upper lip of the flower. The other four are fused in pairs to varying degrees (in Hydrocera still free) and form a two-part lower lip. The exact shape and coloration of the petals and sepals vary greatly depending on the species. There are many extremely decorative species that are used as ornamental plants. In the genus Hydrocera, the flowers are not yet as strongly zygomorphic as in Impatiens, but the characteristics mentioned here still apply to a lesser extent.
Polymoniaceae
Mostly they are annual or perennial herbaceous plants, some species are climbing plants, there are rarely woody plants: subshrubs, shrubs or trees (Cantua). Some species contain colored milky sap. They usually have an unpleasant odor.
The leaves are alternate and spirally arranged, opposite or whorled (Gymnosteris). The leaves are petiolate to sessile. The leaf blade may be simple or compound; if the leaf blade is compound, it may be dissected pinnately or palmately. Leaf margins smooth, toothed, or serrated, stipules absent.
Pentaphylacaceae
Taxa in the family Pentaphylacaceae are shrubs or small trees. The alternate leaves, often arranged in two rows, are divided into a petiole and a leaf blade. The leathery leaf blade is simple. The leaf margin is toothed, wavy, or entire. Side sheets are generally not available.
The flowers are usually singly in the axils of the leaves or are rarely grouped in terminal or lateral inflorescences. The unisexual or hermaphroditic flowers are radially symmetrical and are usually quintuple with a double perianth (perianth). If the flowers are unisexual, then the species is dioecious, dioecious, or androdioecious. The five sepals are free. The five free petals are usually greenish to yellowish in colour, rarely orange-red in colour, for example in Balthazaria. It is just a circle with five stamens or there are usually up to 30 free, fertile stamens present. The filaments are short and the anthers long. In the tribe Frezierieae there are three (one to ten) and in the other tribes five carpels are fused into a mostly superior syncarpic ovary; there is a style with five stigmatic lobes; some authors assume that there are five.
Styracaceae
They are all resinous, woody species: trees and shrubs. They are mostly deciduous, rarely evergreen. The leaves, young twigs, and fruits of the Storax family of trees are almost always covered with complex, star- or shield-shaped, multicellular hairs (trichomes), which often give them a typical silver or brown sheen.
The leaves are alternate and spirally arranged on the branches and are divided into a petiole and a leaf blade. The undivided (simple) leaf-blade has a mostly serrate edge, rarely simple or rarely lobed. The stomata are anomocytic. Stipulations are often absent or very small.
Several genera include species popular as ornamental trees valued for their decorative white flowers. Benzoin resin, used in herbal medicine and perfumes, is extracted from the bark of Styrax species.
Lecythicaceae
These woody plants grow mostly as evergreen trees or shrubs, rarely as lianas. The alternate and spirally arranged leaves, concentrated at the ends of the branches or distributed in two rows on the branches, are simple and petiolate with a smooth (dented or) leaf margin. The stipulations are small or absent.
Primulaceae
They are herbaceous plants or woody plants. Herbaceous species are rarely annual, mostly perennial, and form rhizomes or tubercle-like organs or surviving stolons. Woody plants have a wide spectrum of growth forms, from subshrubs to shrubs, trees, and lianas. Some taxa contain milky colored sap in the sclerotic canals.
The leaves are alternate and spiral or opposite, often arranged in basal rosettes or distributed along the stem (phyllotaxis). The petiolate or sessile leaves are usually simple. There are often dark spots or lines of glands on the leaf blades. Leaf margins may be smooth or toothed. missing stipulations.
The flowers are solitary or in inflorescences of different shapes. The hermaphrodite, radially symmetrical flowers are usually quintuple (from three to nine) and with a double perianth. The green sepals are fused. The petals are usually fused together (sympetalia); in Glaux they are absent; in some taxa the petals are more or less deeply forked. There are one or two circles with usually five free stamens present. Five carpels are for a neglected mostly superior ovary. The ovary contains few to many ovules in free central placentation. There is a stylus with a scar. Heterostyly is common. Pollination is by insects (entomophily).
Sarraceniaceae
All species are herbaceous perennials growing from a rhizome usually in a basal rosette, occasionally (Heliamphora) on an upright stem, alternately arranged tubular leaves serving as insect traps.
Leaves have a short stalk, stipules absent. They transform into complex, more or less elongated, tubular traps, often pitcher-shaped, filled with digestive fluid and running along a single or double wing crest (wing) on the axial side. At the end of the side opposite the axis, a hood-shaped extension is attached, the leaf opening is surrounded by a more or less clearly defined peristome. The leaves are covered with specialized glands on their outer and inner surfaces. Phyllodes are occasionally found.