The ''Circaea'', or enchanter's nightshades, are a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s in the evening primrose family

Onagraceae The Onagraceae are a family of flowering plants known as the willowherb family or evening primrose family. They include about 650 species of herbs, shrubs, and trees taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

have been described, including eight

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. Plants of the genus occur throughout the

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

and

boreal forest Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by pinophyta, coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. I ...

s of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

. Three taxa occur in North America: ''

Circaea alpina ''Circaea alpina'', commonly called alpine enchanter's nightshade, small enchanter's nightshade, or dwarf enchanter's nightshade is a 10–30 cm tall perennial herb found in cool forests of the Northern Hemisphere. Description The leaves ar ...

'', ''

Circaea canadensis ''Circaea canadensis'', known as eastern enchanter's nightshade, Canada enchanter's nightshade, broad-leaved enchanter's nightshade, is a perennial herbaceous plant Herbaceous plants are vascular plants that have no persistent woody stems ab ...

'', and the

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

''Circaea'' × ''sterilis''. The generic name ''Circaea'' refers to the enchantress

Circe In Greek mythology, Circe (; ) is an enchantress, sometimes considered a goddess or a nymph. In most accounts, Circe is described as the daughter of the sun god Helios and the Oceanid Perse (mythology), Perse. Circe was renowned for her vast kn ...

from

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

who is said to have used the herb as a charm.

Description

Members of genus ''Circaea'' are

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

herbaceous plant Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition o ...

s with erect stems, which may or may not be branched. The stem leaves are opposite and petiolate, with toothed edges (i.e., with dentate leaf margins). The inflorescence is a terminal, erect

raceme A raceme () or racemoid is an unbranched, indeterminate growth, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are ...

, with additional racemes at the apices of stem branches (if any). Flowers are dimerous with 2

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s, 2

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s, and 2

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s. The sepals, petals, and stamens alternate such that the stamens ultimately align with the sepals. The petals are white or pink in color. The fruit is a capsule with one or two seeds. Plants disperse their seeds by producing burrs that adhere to clothing, fur, and feathers.

Taxonomy

In 1753, Swedish botanist

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

established the genus ''Circaea'' by describing two species, ''Circaea lutetiana'' and ''Circaea alpina''. Linnaeus also described a variety of ''C. lutetiana'', which later became known as ''Circaea canadensis''. The generic name ''Circaea'' refers to the enchantress

from

. Botanists in the late 16th century believed Circe used the herb to charm Odysseus' companions, hence the common name enchanter's nightshade (not to be confused with the

nightshade family Solanaceae (), commonly known as the nightshades, is a family of flowering plants in the order Solanales. It contains approximately 2,700 species, several of which are used as agricultural crops, medicinal plants, and ornamental plants. Many me ...

of plants, which are unrelated). Molecular evidence indicates the closest relative to ''Circaea'' is the lineage that gave rise to the genus ''

Fuchsia ''Fuchsia'' ( ) is a genus of flowering plants that consists mostly of shrubs or small trees. Almost 110 species of ''Fuchsia'' are recognized; the vast majority are native to South America, but a few occur north through Central America to Mex ...

'', which diverged from it around 41 million years ago.

Taxa

Plants of the World Online Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew. History Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...

(POWO) accepts eight

and eight

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

: * ''

'' ** ''Circaea alpina'' subsp. ''alpina'' ** ''Circaea alpina'' subsp. ''angustifolia'' ** ''Circaea alpina'' subsp. ''caulescens'' ** ''Circaea alpina'' subsp. ''imaicola'' ** ''Circaea alpina'' subsp. ''micrantha'' ** ''Circaea alpina'' subsp. ''pacifica'' * ''

'' ** ''Circaea canadensis'' subsp. ''canadensis'' ** ''Circaea canadensis'' subsp. ''quadrisulcata'' * '' Circaea cordata'' * '' Circaea erubescens'' * '' Circaea glabrescens'' * '' Circaea lutetiana'' * '' Circaea mollis'' * '' Circaea repens'' POWO also recognizes eight named hybrids: * ''Circaea'' × ''decipiens'' * ''Circaea'' × ''dubia'' * ''Circaea'' × ''intermedia'' * ''Circaea'' × ''mentiens'' * ''Circaea'' × ''ovata'' * ''Circaea'' × ''skvortsovii'' * ''Circaea'' × ''sterilis'' * ''Circaea'' × ''taronensis'' For example, the parents of ''Circaea'' × ''sterilis'' are ''C. alpina'' and ''C. canadensis''. The hybrid is sterile but spreads vigorously by vegetative means.

Distribution

Members of genus ''Circaea'' occur throughout the

and

s of the

, from near sea level to altitude, and from 10°–70° N latitude. ''Circaea alpina'' is the most widespread species, ranging across North America, Europe, and Asia. Likewise ''Circaea canadensis'' ranges across continents, in North America, European Russia, and Asia. ''Circaea lutetiana'' occurs throughout Europe, ranging eastward to Iran. Three taxa are known to occur in North America: ''Circaea alpina'', ''Circaea canadensis'', and the hybrid ''Circaea'' × ''sterilis''. ''C. alpina'' is wide ranging across the continent, from California to Alaska in the west, and from Newfoundland to North Carolina in the east, while ''C. canadensis'' is confined to the eastern half of North America. The hybrid, ''C.'' × ''sterilis'', is found wherever the ranges of its parent species overlap.

References

External links

Natural England.
Accessed July 2011

Accessed July 2011

Accessed July 2011 * * {{Taxonbar, from=Q158100 Taxa named by Joseph Pitton de Tournefort Plants described in 1753 Taxa named by Carl Linnaeus Onagraceae genera