词条 | Dipsacales |
释义 | Dipsacales plant order Introduction ![]() Typically, plants in Dipsacales have opposite, often gland-toothed leaves, flowers in cymose (flat-topped) clusters, petals fused into a corolla tube (either regular or bilaterally symmetrical), and inferior ovaries. In most genera petals are alike in shape, but some members of the order develop two-lipped flowers in which one half of the flower is the mirror image of the other half (bilateral symmetry). Most members of the order are shrubby, but there are a few herbaceous members as well. The delimitation of families in this order is disputed, varying from two (Adoxaceae and a very broadly defined Caprifoliaceae) to seven (by splitting off Dipsacaceae, Valerianaceae, Linnaeaceae, Morinaceae, and Diervillaceae from Caprifoliaceae). Dipsacales 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). Adoxaceae Adoxaceae used to include only the herbaceous genera Adoxa and Sinadoxa, but two more genera, Viburnum (175 species) and Sambucus (elderberry, 9 species), were added under APG II. These latter genera are found mostly in the northern temperate zone, but Viburnum also grows on some tropical mountains. Viburnum has simple leaves and flowers with three carpels (of which two abort), but the other genera have compound leaves and five carpels. The inflorescence of Adoxaceae is usually flat-topped and has numerous small flowers. The flowers have five petals (or, more rarely, four petals), are radially symmetric (with many planes of symmetry), and have lobed stigmas on a short style, a fleshy nectary atop the ovary, and fleshy fruits (a drupe). Some dogwood plants look rather similar to Viburnum, but they have four-merous flowers. Viburnum is sometimes mistaken for Hydrangea because in both genera the external flowers of the inflorescence can be sterile and enlarged. Hydrangea, however, is a member of Cornales (the dogwood order) and has distinct, unfused petals, and it has twice as many stamens as petals. The diversity of habitat found in Dipsacales is illustrated by the species of viburnum growing naturally in eastern North America. V. edule (red-fruited squashberry) inhabits moist woods from Labrador to Alaska, southward into Pennsylvania, Michigan, and Minnesota, and as far west as Colorado and Oregon. V. dentatum (arrowwood) thrives not only in moist woods but also in swamps. V. nudum (possum haw) is largely limited to swamps of the eastern and southern coastal plain of the United States. In contrast, V. rufidulum (southern black haw) and V. molle prefer dry, rocky woods or hills. Viburnum is also an important horticultural genus; some of its cultivated species include V. opulus (guelder rose), V. dentatum (arrowwood), and V. macrocephalum (Chinese snowball). Adoxa moschatellina (muskroot) is widely distributed in northern regions. It is a low-growing perennial herb composed of a basal cluster of leaves and a single stem. It has a musky odour (as its name implies), and its cultivation is limited to rock gardens. Caprifoliaceae and related families ![]() ![]() Dipsacaceae ![]() Another important genus of Dipsacaceae is Scabiosa (scabious), the pin-cushion flower genus with 80 species, of which at least 20 species are ornamentals. Cephalaria has 65 species, including cornfield weeds such as C. syriaca and the ornamental C. transylvanica, a tall annual that produces large, stiff, globe-shaped, white to bluish flower heads and has divided leaves. Knautia has 60 species, some cultivated, such as K. arvensis (field scabious). Succisa pratensis (devil's bit scabious), a blue-flowered perennial, grows wild in European meadows. Its leaves are entire or slightly lobed and oval to narrow in shape. Valerianaceae Valerianaceae, or the valerian family, contains 17 genera and 315 species, most of them in the genera Valeriana (200 species) and Valerianella (80 species). Members of this family are characterized by the rank odour of their stems and leaves when dried; they are herbs or small shrubs with small regular to monosymmetric flowers, usually with a spur. They are distributed in the Northern Hemisphere and in Andean South America. Valeriana officinalis (garden heliotrope (heliotrope)) is a perennial herb prized for its spicy, fragrant flowers; it is native in Europe and Western Asia. Its dried rhizome yields valerian, a natural sedative. Nardostachys grandiflora ( spikenard) is a perennial herb of the Himalayas that produces an essential oil in its woody rhizomes. Linnaeaceae ![]() Morinaceae Morinaceae contains 3 genera (Acanthocalyx, Cryptothladia, and Morina) with 13 species native to Eurasia, from the Balkans to China. They are robust perennial herbs with leaves joined at the base and flower clusters in successive whorls (verticillasters or heads). Flowers are bilaterally symmetric and subtended by an extra whorl called the epicalyx. In the Balkans the seeds of Morina persica are eaten like rice. Diervillaceae Diervillaceae contains 2 genera, Diervilla, with 3 North American species, and Weigelia, with 10 East Asian species. Many of these are cultivated as ornamental shrubs in temperate areas for their colourful flowers. |
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