Asteraceae
Introduction
The Asteraceae, also known as the Compositae, is a large and widespread family of flowering plants. The family currently comprises 32,913 accepted species names, in 1,911 genera (list) and 13 subfamilies. In terms of numbers of species, the Asteraceae are rivaled only by the Orchid family. They are most common in the temperate regions and tropical mountains, but they occur in all habitats, the family has a worldwide distribution.
Taxonomy and Phylogeny
The name Asteraceae comes from Aster, the most prominent genus in the family, which derives from the Greek word for star, and refers to the star-like form of the inflorescence. Members of the Asteraceae are colloquially known as the aster, daisy, or sunflower family. The family was first described by French botanist Antoine Laurent in 1789.
The Asteraceae family is taxonomically complex. It has undergone significant revision in recent years, particularly regarding the classification of species into tribes and subfamilies. The family is currently divided into 13 subfamilies, including Asteroideae, Carduoideae, and Cichorioideae, among others.
Morphology
Asteraceae are mostly herbaceous plants, but some shrubs, trees, and climbers exist as well. They are characterized by their composite inflorescences, which are made up of many small flowers, or florets, arranged in a head, or capitulum. The capitulum is a unique type of inflorescence found in the Asteraceae, and it gives the appearance of a single flower.
The flowers of Asteraceae are typically small and often indistinguishable to the naked eye. However, they are usually grouped together in a dense head, or capitulum, which is surrounded by a ring of bracts, or phyllaries. This arrangement can create a wide variety of appearances, from the daisy-like flowers of the genus Bellis, to the thistle-like flowers of the genus Cirsium.
Distribution and Habitat
The Asteraceae family is widespread and can be found in a variety of habitats. They are most common in the temperate regions and tropical mountains. However, they can also be found in habitats ranging from cold tundra to hot deserts. Some species have adapted to live in poor conditions, such as dunes, rocky outcrops, and wastelands.
Economic Importance
Many members of the Asteraceae family have economic importance. Some, like lettuce (Lactuca sativa), sunflower (Helianthus annuus), and artichoke (Cynara scolymus), are important food crops. Others, like the dandelion (Taraxacum officinale), are considered weeds. Still others, like the Echinacea and Rudbeckia, are grown as ornamental plants.
Conclusion
The Asteraceae family is a diverse and widespread group of plants. Its members exhibit a wide range of forms and are found in nearly every habitat on Earth. Despite its complexity, the family is united by its unique inflorescence structure, the capitulum, which has allowed it to colonize a wide range of habitats and become one of the most successful plant families on the planet.