''Orostachys'' is a genus of the succulent family

Crassulaceae The Crassulaceae (, from Latin ''crassus'', thick), also known as the crassulas, the stonecrops or the orpine family, are a diverse Family (biology), family of dicotyledon angiosperms primarily characterized by succulent leaves and a form of phot ...

(stonecrop family) that contains about 15 species. It is a biennial herb growing in China, Japan, Kazakhstan, Korea, Mongolia, Russia. Eight species occur in China.

Description

''Orostachys'' are the most morphologically distinct member of subfamily Sempervivoideae. Orostachys species are mostly biennial

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 ...

plants that are more or less succulent.

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 linear to ovate, often with dull purple dots. The arrangement is

alternate Alternative or alternate may refer to: Arts, entertainment and media * Alternative (''Kamen Rider''), a character in the Japanese TV series ''Kamen Rider Ryuki'' * Alternative comics, or independent comics are an alternative to mainstream superh ...

, forming crowded

cauline 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, fl ...

rosettes. Especially the thick-fleshed foliage stores water. The leaf ends have a cartilaginous to spiny, white tip. Leaf margins are usually smooth.

Stipules In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part of the anatomy ...

are absent. The

root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often bel ...

s are fibrous and there is no

rhizome In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...

. In the first year, the leaves stand together in solitary, basal, dense rosettes. In the second year, a solitary, leafy

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

, 5 to 60 cm in length, arises from the center of the rosette and forms flowers. The terminal

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 ...

s, usually branched and composed of individual spicate inflorescences, are relatively large and narrowly pyramidal to cylindrical, containing many flowers and foliage-like

bract In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

s. The

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s, which are at most very short-stemmed, are hermaphroditic and pentamerous. The free

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 are usually shorter than the

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. The five predominantly yellow, rarely white, yellow-green, or pinkish to reddish petals are almost free. There are two circles with five

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 yellowish

nectar Nectar is a viscous, sugar-rich liquid produced by Plant, plants in glands called nectaries, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to an ...

y scales are relatively small. The erect

carpels Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ...

are free and contain many

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the sporangium, megasporangium), ...

s. The styles are narrow. The many-seeded follicles possess a beak-like end. The seeds are small.

Taxonomy

Within family

, ''Orostachys'' is placed in tribe Telephieae of subfamily Sempervivoideae. The genus has at times included '' Meterostachys''.

Molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

shows that the genus is not

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

, but

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

with respect to '' Hylotelephium''. Its

circumscription Circumscription may refer to: * Circumscribed circle * Circumscription (logic) *Circumscription (taxonomy) * Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthr ...

, therefore, is unstable and subject to revision.

Subdivision

The genus ''Orostachys'' has been divided into series (or sections), including: * ''Orostachys'' series ''Appendiculatae'' * ''Orostachys'' series ''Eappendiculatae'' Other authors have created two different sections: * ''Orostachys'' section ''Orostachys'' * ''Orostachys'' section ''Schoenlandia'' Some species were transferred from ''Sinocrassula'' into ''Orostachys'', as section ''Schoenlandia'', also treated as a subgenus or section, or a separate genus '' Kungia'', e.g. ''O. schoenlandii'' (''Kungia schoenlandii''). ''Orostachys'' section ''Orostachys'', in turn has been treated as two subsections, differing by either flat or fleshy leaf shape, and the presence or absence of appendages on the leaves, which include spines or cartilaginous protrusions: * ''Orostachys'' subsection ''Orostachys'' * ''Orostachys'' subsection ''Appendiculatae'' On the basis of molecular data, it has been proposed that ''Orostachys'' subsection ''Appendiculatae'' be considered a separate genus.

Species

The genus includes about 12–17 accepted species, including: * '' Orostachys aggregata'' (Makino) H. Hara * '' Orostachys boehmeri'' V.N. Boriss. – also called ''O. furusei'', endemic plant from Japan *'' Orostachys cartilaginea'' (H. Lév.) A. Berger * '' Orostachys chanetii '' A. Berger * '' Orostachys fimbriata'' (Turcz.) A.Berger * '' Orostachys genkaiensis'' Ohwi * '' Orostachys iwarenge '' Hara – Chinese Dunce Cap * '' Orostachys malacophylla'' (Pall.) Fisch. – type species * '' Orostachys minuta'' (Kom.) A. Berger * '' Orostachys paradoxa'' (Khokhr. & Vorosch.) Czerep. * '' Orostachys sikokiana'' (Makino) Ohwi * '' Orostachys spinosa'' (L.) Sweet * '' Orostachys thyrsiflora'' Fisch.

References

Bibliography

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) * * * * * , in Flora of China online vol. 8 {{Taxonbar, from=Q141475 Crassulaceae Crassulaceae genera