Roscoea alpina
Encyclopedia
Roscoea alpina is a perennial herbaceous plant
Herbaceous plant
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...

 native to the Himalayas, from Kashmir
Kashmir
Kashmir is the northwestern region of the Indian subcontinent. Until the mid-19th century, the term Kashmir geographically denoted only the valley between the Great Himalayas and the Pir Panjal mountain range...

 to Burma. Most members of the ginger family (Zingiberaceae
Zingiberaceae
Zingiberaceae, or the Ginger family, is a family of flowering plants consisting of aromatic perennial herbs with creeping horizontal or tuberous rhizomes, comprising ca. 52 genera and more than 1300 species, distributed throughout tropical Africa, Asia, and the Americas.Many species are important...

), to which it belongs, are tropical, but R. forrestii, like other species of Roscoea
Roscoea
Roscoea is a genus of perennial plants of the family Zingiberaceae . Most members of the family are tropical, whereas Roscoea species are native to mountainous regions of the Himalayas, China and its southern neighbours. Roscoea flowers superficially resemble orchids, although they are not related...

, grows in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens.

Description

Roscoea alpina is a perennial herbaceous plant
Herbaceous plant
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...

 from the Himalayas. It is found all along the Himalayas, from Kashmir
Kashmir
Kashmir is the northwestern region of the Indian subcontinent. Until the mid-19th century, the term Kashmir geographically denoted only the valley between the Great Himalayas and the Pir Panjal mountain range...

, Tibet
Tibet
Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...

, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...

, Sikkim
Sikkim
Sikkim is a landlocked Indian state nestled in the Himalayan mountains...

 and Bhutan
Bhutan
Bhutan , officially the Kingdom of Bhutan, is a landlocked state in South Asia, located at the eastern end of the Himalayas and bordered to the south, east and west by the Republic of India and to the north by the People's Republic of China...

 through to Burma. In Tibet
Tibet
Tibet is a plateau region in Asia, north-east of the Himalayas. It is the traditional homeland of the Tibetan people as well as some other ethnic groups such as Monpas, Qiang, and Lhobas, and is now also inhabited by considerable numbers of Han and Hui people...

 it grows in coniferous forests between 3,000 and 3,600 metres.

Like all members of the genus Roscoea, it dies back each year to a short vertical rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...

, to which are attached the tuberous roots
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...

. When growth begins again, "pseudostems" are produced: structures which resemble stems but are actually formed from the tightly wrapped bases (sheaths) of its leaves. R. alpina is one of the smaller members of the genus; plants are 10–20 cm tall, with four to six leaves. The first two or three leaves consist only of a sheath; the remaining two or three have in addition a smooth (glabrous) leaf blade, free from the pseudostem, 3–12 cm long by 1.2–2 cm wide. There is a very small ligule, extending to about 0.5 mm, at the junction of the leaf sheath and blade. The leaf blades taper to a point.

In its native habitats, R. alpina flowers between May and August. The stem (peduncle
Peduncle (botany)
In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green and without leaves, though sometimes colored or supporting small leaves...

) of the flower spike is hidden by the leaf sheaths. At the base of the flower spike there is a small bract, 3–10 mm long. Flowers open in succession and are purple or lilac in colour.

Each flower has the typical structure for Roscoea
Roscoea
Roscoea is a genus of perennial plants of the family Zingiberaceae . Most members of the family are tropical, whereas Roscoea species are native to mountainous regions of the Himalayas, China and its southern neighbours. Roscoea flowers superficially resemble orchids, although they are not related...

(see the diagrams in that article). There is a tube-shaped outer calyx, 4–5 cm long with a two-lobed apex. Next the three petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...

s (the corolla) form a tube which is longer than the calyx and terminates in three lobes, an upright more-or-less circular central lobe, about 1.5 cm in diameter (which forms a hood over the rest of the flower), and two more elongated side lobes. Inside the petals are structures formed from four sterile stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...

s (staminodes): two lateral staminodes form what appear to be upright petals, smaller than the corolla lobes; two central staminodes are fused to form a lip or labellum, about 1.5 cm long, which is divided at the end into two lobes.

The single functional stamen has a white or cream anther, about 5–6 mm long, with 1.5–2 mm long spurs formed from the connective tissue between the two capsules of the anther. The ovary expands to a 2.5–3.5 cm long capsule when seed is set.

Taxonomy

Roscoea alpina was first described scientifically in 1839 by John Forbes Royle
John Forbes Royle
John Forbes Royle , British botanist and teacher of materia medica, was born in Kanpur in 1799. Entering the service of the East India Company as assistant surgeon, he devoted himself to studying botany and geology, and made large collections among the Himalaya Mountains...

, a British botanist who was born in India and worked for the East India Company
British East India Company
The East India Company was an early English joint-stock company that was formed initially for pursuing trade with the East Indies, but that ended up trading mainly with the Indian subcontinent and China...

. The specific epithet refers to the alpine habitat
Alpine plant
Alpine plants are plants that grow in the alpine climate, which occurs at high elevation and above the tree line. Alpine plants grow together as a plant community in alpine tundra.-Alpine plant diversity:...

 of the species.

Evolution and phylogeny

The Zingiberaceae family is mainly tropical in distribution. The unusual mountainous distribution of Roscoea may have evolved relatively recently and be a response to the uplift taking place in the region in the last 50 million years or so due to the collision of the Indian and Asian tectonic plates
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

.

Species of Roscoea divide into two clear groups, a Himalayan clade and a "Chinese" clade (which includes some species from outside China). The two clades correspond to a geographical separation, being divided by the Brahmaputra River
Brahmaputra River
The Brahmaputra , also called Tsangpo-Brahmaputra, is a trans-boundary river and one of the major rivers of Asia. It is the only Indian river that is attributed the masculine gender and thus referred to as a in Indo-Aryan languages and languages with Indo-Aryan influence...

 as it flows south at the end of the Himalayan mountain chain. It has been suggested that the genus may have originated in this area and then spread westwards along the Himalayas and eastwards into the mountains of China and its southern neighbours. R. alpina falls into the Himalayan clade as would be expected from its distribution. It appears to be closely related to R. auriculata
Roscoea auriculata
Roscoea auriculata is a perennial herbaceous plant occurring in the eastern Himalayas, in Tibet, Bhutan, Nepal and Sikkim. Most members of the ginger family , to which it belongs, are tropical, but R. auriculata, like other species of Roscoea, grows in much colder mountainous regions...

.

Cultivation

Some Roscoea species and cultivars, including R. alpina, are grown in rock gardens. They generally require a relatively sunny position with moisture-retaining but well-drained soil. As they do not appear above ground until late spring or even early summer, they escape frost damage in regions where subzero temperatures occur. When grown at Royal Botanic Gardens, Kew
Royal Botanic Gardens, Kew
The Royal Botanic Gardens, Kew, usually referred to as Kew Gardens, is 121 hectares of gardens and botanical glasshouses between Richmond and Kew in southwest London, England. "The Royal Botanic Gardens, Kew" and the brand name "Kew" are also used as umbrella terms for the institution that runs...

, R. alpina requires more shade than other species of Roscoea. It flowers in late spring to early summer, the leaves elongating afterwards. White forms are known.

The height reached in cultivation, up to 40 cm, exceeds that given for the species in the wild, where it is said to reach only 20 cm.

For propagation, see Roscoea: Cultivation.
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