Achariaceae
- Related Topics:
- Turneraceae
- Humiriaceae
- Violaceae
- Bonnetiaceae
- Euphroniaceae
Achariaceae contains 30 genera and 145 species of shrubs to trees, or rarely climbing herbs, which are scattered throughout the tropics. The Indo-Malesian Hydnocarpus (40 species) is the largest genus in the family. Ryparosa (18 species) is Malesian, and Lindackeria (14 species) grows in the Americas and Africa. Most species of Achariaceae were previously included in Flacourtiaceae, while Achariaceae in the original sense was a small and little-known family of herbaceous or semishrubby plants from Africa.
Florally, members of Achariaceae are distinctive in that the parts are spiral, not whorled, or if it is whorled, there are more petals than sepals, and the petals have a scale at the base on their inner surface. There are often numerous stamens. The seeds are distinctive because of the vascular bundles clearly visible on their surfaces. The seeds of Hydnocarpus are a source of chaulmoogra oil, at one time important in the treatment of leprosy. The presumed active agent in the oil, hydnocarpic acid, is believed to have antibiotic properties. The seeds of Caloncoba echinata, from west-central Africa, are the source of gorli oil, also used in the treatment of leprosy. (These old treatments for leprosy have been replaced by sulfone drugs and other modern antibiotics.) Achariaceae is chemically quite different from Salicaceae in that many members have cyanogenic compounds of a very distinctive type.
Turneraceae
Members of Turneraceae, a family of 10 genera and 205 species, are found in the tropical and subtropical parts of the Americas, Africa, Madagascar, and the Mascarene Islands. Turnera (122 species) and Piriqueta (44 species) are both found in the Neotropics and Africa. Members of the family often have hairy toothed leaves with strong secondary venation but they lack stipules. In the flowers, the calyx and corolla together form a tube, and the petals overlap regularly and soon become deliquescent after wilting—that is, instead of drying as they wilt, they become soggy. The stigmas are often bifid and fringed. The capsular fruits have arillate seeds with a minutely and often regularly reticulate testa.
Smaller families
Malesherbiaceae contains only Malesherbia (24 species), a genus of herbs and shrubs from often dry regions of western subtropical South America. Members of Malesherbiaceae are fetid and often densely glandular hairy plants with distinctive flowers. The calyx and corolla tube is persistent in fruit. The stamens and ovary are borne on top of a short stalk or androgynophore.
Lacistemataceae is a small family of 2 genera and 14 species native to the tropical and subtropical Americas and the West Indies. Lacistema includes 11 species. The flowers are very reduced and are sometimes borne in almost catkinlike inflorescences.
Goupiaceae is a small family of evergreen trees with two species growing in northeastern South America. The leaves have parallel cross veins, and the inflorescences are umbellate. The petals are long, the apical part being inflexed. The fruit is a drupe.
Erythroxylaceae and Rhizophoraceae
Erythroxylaceae and Rhizophoraceae are very close, having similar distinctive chemistry and cell microstructure.
Erythroxylaceae, or the coca family, contains 4 genera and 240 species of smallish trees to shrubs, which are pantropical but mostly American. The family has entire, mostly alternate leaves without teeth and with stipules that in many species grow between the petiole and the stem. The rather small flowers are in groups in the leaf axils, and both sepals and filaments persist at the base of the fruit. Erythroxylum (230 species) is by far the largest genus in the family and has stamens that are usually joined at the base and of two different lengths. The fruits are fleshy drupes. The dried leaves of E. coca and E. novogranatense are still chewed by Amerindians in western South America, and both are a source of cocaine, which makes it a major (mostly illicit) crop in parts of Colombia, Peru, and Bolivia. A lowland variety of E. coca (ipadu) is cultivated in the Amazon basin of Colombia, Ecuador, Peru, and Brazil. One variety of coca is legally grown in northern Peru and is used as a flavouring for the soft drink Coca-Cola (a name that is derived from the plant). Aneulophus (2 African species, A. africana and A. africanus) is much more like Rhizophoraceae than other Erythroxylaceae.
Rhizophoraceae, or the mangrove family, contains 16 genera and 149 species of trees that grow throughout the tropics. Three small genera, Rhizophora, Kandelia, and Bruguiera, are mangrove plants, and all grow in the Southeast Asia–Malesia area, but Rhizophora alone is pantropical. Cassipourea (62 species), native to Africa, the Americas, and Sri Lanka, Carallia (10 species), native from Madagascar to Australia, and other members of the family grow in tropical forests.
Rhizophoraceae have opposite leaves and large stipules, and they often have aerial roots. The petals are often lobed and hairy or with very narrow appendages. The ovary is more or less inferior. Seeds of the mangrove-dwellers have little endosperm and are viviparous—that is, they germinate precociously while still on the mother plant. The long pointed seedling root dangling from the trees is very characteristic. However, less-specialized Rhizophoraceae have capsular fruits with arillate seeds.
The main importance of the family is ecological, because mangroves form dense vegetation along the coast and in estuaries in the tropics that protects the land from erosion and the effects of tropical storms. The bark of mangrove is used in tanning, and the wood is used for pulp and in building.
The Clusiaceae group
Clusiaceae, Bonnetiaceae, Podostemaceae, and Hypericaceae have many anatomical features in common. Their inflorescence is cymose; their petals overlap each other regularly in bud; and their flowers lack a nectary. Their capsular fruit opens down the radii of the partitions, and their seeds and embryo are distinctive. Within this group, Clusiaceae, Bonnetiaceae, and Podostemaceae all share a rather unusual class of chemical called xanthones. Members of these families often have many stamens, which tend to be in bundles. Clusiaceae and Podostemaceae have canals, cavities, or individual cells with exudate, and their ovules have only a single layer of cells over the embryo sac.
Clusiaceae and Bonnetiaceae have long been associated, even if Bonnetiaceae has in turn been linked to Theaceae (order Ericales), and they have many features in common with Elatinaceae. However, molecular data have shown a surprisingly close association of Clusiaceae and Bonnetiaceae with Podostemaceae. Indeed, Podostemaceae turns out to be particularly close to Hypericum and its immediate relatives, which has led to the latter’s being reorganized into its own family, Hypericaceae. Podostemaceae species are so highly modified for life as aquatics that it was unclear as to what their relationships were before modern DNA analysis suggested a particular association with Clusiaceae.
Clusiaceae
Clusiaceae, or the garcinia family, contains 27 genera and 1,050 species, distributed worldwide, which are mostly woody shrubs to trees, some epiphytic, a few lianas, and a few herbs. Clusia (300–400 species) is restricted to the New World. Garcinia (240 species, including former genera such as Rheedia and Tripetalum) is especially common in the Old World. Calophyllum (about 190 species) is found mostly in the Old World. Mammea (about 75 species) is found throughout the tropics, with many species in Madagascar. Kayea (about 70 species) includes one species from Sri Lanka, with most of the rest from western Malesia. Kielmeyera (50 species) is native to South America, especially Brazil. Chrysochlamys (55 species, including former genera such as Tovomitopsis) grows throughout the Neotropics.
Clusiaceae usually have opposite leaves that lack stipules; the margins of the blades lack teeth, and there are nearly always quite obvious glands or canals; there is often some exudate from the cut twig. The numerous stamens are quite often in bundles, and there are frequently various kinds of glands on the anthers. Plants with hermaphroditic flowers are common, but Clusia and Garcinia, in particular, have male and female flowers on different plants. Both fruits and seeds are highly variable. Seeds may be variously winged, have fleshy arils, or be borne in single-seeded berries or drupes. The seed may be made up almost entirely of massive cotyledons, or it may be equally massive but made up of the stem immediately below the cotyledons, which are reduced. Although little is known about pollinators, there is evidence that in South America, at least, bees visit the family for the oils and resins the flowers contain. Only in a very few genera, such as Symphonia, do birds and other visitors take nectar from the flowers. The exudate from some members of Clusiaceae is used medicinally. The principal edible fruits are mammee apples (M. americana) and mangosteens (the incomparable but rather slow-to-grow G. mangostana), although the fruits of other species of Garcinia also are edible. Calophyllum species yield useful timber; C. inophyllum and C. brasiliense are important in canoe manufacture.
Bonnetiaceae
Bonnetiaceae contains 3 genera and 35 species of evergreen shrubs. Ploiarium (3 species) is native to Malesia; Archytaea (2 species) is native to South America; Bonnetia (30 species) is native to South America, with one species from Cuba. Some Bonnetia grow at high altitudes on the tepuis of South America. Their leaves may then be borne in rosettes, and their stems are stout. Bonnetiaceae have long-pointed buds, usually rather closely set, spiral and minutely toothed leaves, and large flowers with many stamens.
Podostemaceae
Podostemaceae, or the riverweed family, contains about 48 genera and 270 species of annual and perennial herbs that grow in fast-flowing water. The family is largely tropical, especially in the Americas, but the number and limits of genera are unclear. The South American Apinagia has about 50 species. The plant body of Podostemaceae is so highly modified that ordinary botanical terms cannot be used to describe it, and they often look like small versions of marine algae such as kelp. There is no main root, and the plant body of many taxa is best described as like a thallus, although some species look like odd members of Apiaceae but with two-ranked leaves. The shoots arise from the roots, and the plant is attached to the substrate by a holdfast or haptera. The flowers or groups of flowers are produced above water when the river level drops in dry periods; they are often enveloped by a sheathing bractlike structure, and the small seeds are often mucilaginous.
Hypericaceae
Hypericaceae consists of nine genera, of which Hypericum (about 370 species) is the most common genus in temperate areas and on tropical mountains. Other genera include Vismia (55 species), which is probably restricted to the Neotropics, and Harungana (50 species), native to Africa and Madagascar. Hypericum species are much used in herbal medicines but can be dangerous; H. perforatum is a serious weed in parts of North America, and it can photosensitize livestock that eat it. Several species of Hypericum are of horticultural value.
