''Helianthemum'' (), known as rock rose, sunrose, rushrose, or frostweed,''Helianthemum''.
Integrated Taxonomic Information System (ITIS). is 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 ...

of about 110''Helianthemum''.
Flora of China. species of

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

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Cistaceae The Cistaceae are a small family of plants (rock-rose or rock rose family) known for their beautiful shrubs, which are profusely covered by flowers at the time of blossom. This family consists of about 170(-200) species in eight genera that are ...

. They are widely distributed throughout the Northern Hemisphere, especially in the Mediterranean.

New World The term "New World" is used to describe the majority of lands of Earth's Western Hemisphere, particularly the Americas, and sometimes Oceania."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: ...

species formerly classified as ''Helianthemum'' have been transferred to genus ''

Crocanthemum ''Crocanthemum'' is a genus of flowering plants in the family Cistaceae. They are native to both North and South America where they are widespread. The common name frostweed relates to the ice crystals which form from sap exuding from cracks near ...

''.

Description

These are usually

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s or subshrubs, and some are

herbaceous 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 of ...

annuals or perennials. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are oppositely arranged, but some plants may have alternately arranged leaves along the upper stems. The flowers are solitary or borne in an array of

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

types, such as

panicle In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a p ...

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 ...

s, or headlike clusters. The flower has three inner

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 and two smaller outer sepals. It has five petals usually in shades of yellow, orange, or pink. The

style Style, or styles may refer to: Film and television * ''Style'' (2001 film), a Hindi film starring Sharman Joshi, Riya Sen, Sahil Khan and Shilpi Mudgal * ''Style'' (2002 film), a Tamil drama film * ''Style'' (2004 film), a Burmese film * '' ...

at the center is tipped with a large stigma. The fruit is a capsule containing many seeds.

Ecology

''Helianthemum'' are known to form

symbioses Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term

mycorrhiza A mycorrhiza (; , mycorrhiza, or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play ...

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. In the Mediterranean they are associated with

Terfeziaceae The Terfeziaceae, or desert truffles, is a family of truffles (, , , ) endemic to arid and semi-arid areas of the Mediterranean Region, North Africa, and the Middle East, where they live in ectomycorrhizal association with '' Helianthemum'' ...

, the desert truffles. Together, plant and fungus may have a beneficial effect on the arid local landscapes, preventing

soil erosion Soil erosion is the denudation or wearing away of the Topsoil, upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, Atmosphere of Ea ...

and

desertification Desertification is a type of gradual land degradation of Soil fertility, fertile land into arid desert due to a combination of natural processes and human activities. The immediate cause of desertification is the loss of most vegetation. This i ...

. Some symbiotic pairs include ''Helianthemum salicifolium'' and the truffle ''Tirmania nivea'', and ''H. guttatum'' and ''T. pinoyi''. One of the most commonly observed mycorrhizae on ''Helianthemum'' is a member of a different family, ''

Cenococcum geophilum ''Cenococcum geophilum'' Fr., synonym ''Cenococcum graniforme'' (Sow.) Ferd. and Winge, is an Ascomycete fungal species and is the only member in the genus ''Cenococcum''. It is one of the most common ectomycorrhizal fungal species encountered i ...

''. This fungus is not host-specific, and it often associates with

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

s, as well. Some studies suggest that ''Helianthemum'' and oaks growing together in a habitat may "share" their mycorrhizae. ''Helianthemum'' are food plants for the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e of some

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

species, such as the

large grizzled skipper The Large Grizzled skipper (''Pyrgus alveus'') is a species of skipper (butterfly), skipper butterfly (family Hesperiidae). Description This is a rather variable species with a wingspan of 22–32 mm (not always particularly "large") with severa ...

and the

silver-studded blue The silver-studded blue (''Plebejus argus'') is a butterfly in the family Lycaenidae. It has bright blue wings rimmed in black with white edges and silver spots on its hindwings, lending it the name of the silver-studded blue. ''P. argus'' can be ...

. The

leaf miners A leaf miner is any one of numerous species of insects in which the larval stage lives in, and eats, the leaf tissue of plants. The vast majority of leaf-mining insects are moths ( Lepidoptera), sawflies ( Symphyta, a paraphyletic group whi ...

Bucculatrix helianthemi Bucculatricidae or (Bucculatrigidae) is a family of moths. This small family has representatives in all parts of the world. Some authors place the group as a subfamily of the family Lyonetiidae. Adults of this family are easily overlooked, bein ...

'' and '' B. regaella'' both feed exclusively on ''Helianthemum sessiliflorum'', as does '' Coleophora eupreta''. '' C. ochrea'' is limited to ''Helianthemum'', and '' C. bilineella'' and '' C. potentillae'' have been observed on the genus.

Cultivation

Several ''Helianthemum'' species, and the numerous

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 ...

s and

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s derived from them, are widely grown as

ornamental plant Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...

s, popular in

rockeries A rock garden, also known as a rockery and formerly as a rockwork, is a garden, or more often a part of a garden, with a landscaping framework of rocks, stones, and gravel, with planting appropriate to this setting. Usually these are small A ...

. A broader range of colours is available among the cultivars, including bright salmon-pink to dark red. They are best grown in well-draining soil in full sun, and have a long flowering period from spring to summer. Numerous cultivars have gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...

: *'Amy Baring' (yellow) *'Fire Dragon' *'Henfield Brilliant' (scarlet) *'Jubilee' (pale yellow) *'Mrs C.W. Earle' (red) *'Rhodanthe Carneum' (pink) *'The Bride' (white) *'

Wisley Wisley is a village and civil parish in Surrey, England between Cobham and Woking, in the Borough of Guildford. It is the home of the Royal Horticultural Society's Wisley Garden. The River Wey runs through the village and Ockham and Wisley C ...

Primrose' (primrose yellow)

Species

112 species are accepted. *'' Helianthemum abelardoi'' *'' Helianthemum aegyptiacum'' *'' Helianthemum aganae'' *'' Helianthemum aguloi'' *'' Helianthemum almeriense'' *'' Helianthemum alypoides'' *'' Helianthemum angustatum'' *'' Helianthemum antitauricum'' *''

Helianthemum apenninum ''Helianthemum apenninum'', the white rock-rose, is a white-flowering rock rose of the family Cistaceae found in the North Atlantic region, mainly in dry grassy and rocky places across large parts of Europe. ''Helianthemum apenninum'', is a sel ...

'' – white rockrose *'' Helianthemum × asperilanceolatum'' *'' Helianthemum asperum'' *'' Helianthemum assadii'' *'' Helianthemum baschkirorum'' *'' Helianthemum bilyanense'' *'' Helianthemum bramwelliorum'' *'' Helianthemum broussonetii'' *'' Helianthemum buschii'' *'' Helianthemum bystropogophyllum'' *''

Helianthemum canariense ''Helianthemum canariense'' is a species of flowering plant in the family Cistaceae, native to Western Sahara, Morocco and the Canary Islands. Description ''Helianthemum canariense'' is a short, densely branched shrub up to tall. Its oval leave ...

'' *''

Helianthemum canum ''Helianthemum oelandicum'', commonly called hoary rockrose, is a low-growing plant confined to rocky dry calcareous areas especially close to the sea. Description The plant typically has a central stock from which numerous branches radiate hor ...

Helianthemum nummularium ''Helianthemum nummularium'' (known as common rock-rose) is a species of rock-rose (Cistaceae), native to most of Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is borde ...

Helianthemum tholiforme ''Helianthemum'' (), known as rock rose, sunrose, rushrose, or frostweed,

'' *'' Helianthemum thymiphyllum'' *'' Helianthemum × triregnorum'' *'' Helianthemum ventosum'' *'' Helianthemum vesicarium'' *'' Helianthemum violaceum'' *'' Helianthemum virgatum'' *'' Helianthemum viscarium'' *'' Helianthemum viscidulum'' *'' Helianthemum × xixonense'' *'' Helianthemum zheguliense''

References

External links

Flora Europaea: ''Helianthemum''eFloras search results for ''Helianthemum''
{{Authority control Malvales genera Taxa named by Philip Miller