Roscoea tibetica
Encyclopedia
Roscoea tibetica is a perennial herbaceous plant
native to the mountains of China
, being found in Tibet
, Sichuan
and Yunnan
. The species formerly included plants found in Bhutan
; in 2000, these were separated into a new species, Roscoea bhutanica
. Most members of the ginger family (Zingiberaceae
), to which it belongs, are tropical, but R. tibetica, like other species of Roscoea
, grows in much colder mountainous regions. R. tibetica is sometimes grown as an ornamental plant in gardens.
native to mountains in China
north-east of the Brahmaputra River
, in Tibet
, Sichuan
and Yunnan
. It is found in pine forests, scrub and alpine meadows, at heights of 2,400–3,800 m.
Like all members of the genus Roscoea, it dies back each year to a short vertical rhizome
, to which are attached the tuberous roots
. 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. tibetica is one of the smaller members of the genus; plants are 5–15 cm tall, with one to three leaves, which have blades 2–6 cm long by 1–2.5 cm wide. The blade is more-or-less hairy; more so when young. There is a very small ligule, extending to about 0.5 mm, at the junction of the leaf sheath and blade.
In its native habitats, R. tibetica flowers between June and July. The stem (peduncle
) of the flower spike is hidden by the leaf sheaths. Bracts some 2.2–4 cm long enclose the flowers, which are purple or violet and appear just above the leaves.
Each flower has the typical structure for Roscoea
(see the diagrams in that article). There is a tube-shaped outer calyx, brown-spotted and 3–4 cm long with a three-toothed apex. Next the three petal
s (the corolla) form a tube which is longer than the calyx at 4–5 cm and terminates in three lobes, a narrow upright central lobe, about 1.5–1.7 cm long, forming a hood, and two side lobes, each 1.5–1.8 cm long by 4–5 mm wide. Inside the petals are structures formed from four sterile stamen
s (staminodes): two lateral staminodes form what appear to be upright petals, 1–1.3 cm long; two central staminodes are fused to form a lip or labellum, about 1.4–2.5 cm by 0.8–1.8 cm, which is divided into two lobes for more than half its length.
The single functional stamen has a cream anther, about 5–6 mm long, with 3–7 mm long spurs formed from the connective tissue between the two capsules of the anther. The cylinder-shaped ovary is about 1.5 cm long.
, a Russian botanist. The specific epithet tibetica refers to the location in which the species was found.
As explained further below, in 2000, plants from areas south and west of the Brahmaputra River
were separated off into a new species, R. bhutanica.
.
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
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. tibetica was formerly thought to be unique in occurring on both sides of the Brahmaputra River. However, genetic analysis in 2000 showed that plants from the south of the Brahmaputra River, in Bhutan, were distinct from those from the other side of the river, in China. The former were placed in a new species, R. bhutanica. R. tibetica falls into the Chinese clade whereas R. bhutanica belongs to the Himalayan clade, as would be expected from their respective distributions.
The two species are superficially similar, in that they are both small and have a tight group of basal leaves. Young plants of the two species are not easily distinguished, but later it can be seen that while R. bhutanica develops leaves in two opposite rows, R. tibetica retains a rosette of leaves.
as R. tibetica produced small dark purple flowers, one at a time, from early June to July. The plants were noted as being variable (it is not clear whether any were actually what is now R. bhutanica).
For propagation, see Roscoea: Cultivation.
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 mountains of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, being found 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...
, Sichuan
Sichuan
' , known formerly in the West by its postal map spellings of Szechwan or Szechuan is a province in Southwest China with its capital in Chengdu...
and Yunnan
Yunnan
Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
. The species formerly included plants found in 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...
; in 2000, these were separated into a new species, Roscoea bhutanica
Roscoea bhutanica
Roscoea bhutanica is a perennial herbaceous plant native to the mountains of Bhutan and Tibet. Formerly regarded as part of Roscoea tibetica, it was recognized as a separate species in 2000. Most members of the ginger family , to which it belongs, are tropical, but R...
. 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. tibetica, 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. R. tibetica is sometimes grown as an ornamental plant in gardens.
Description
Roscoea tibetica is a perennial herbaceous plantHerbaceous 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 mountains in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
north-east of 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...
, 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...
, Sichuan
Sichuan
' , known formerly in the West by its postal map spellings of Szechwan or Szechuan is a province in Southwest China with its capital in Chengdu...
and Yunnan
Yunnan
Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
. It is found in pine forests, scrub and alpine meadows, at heights of 2,400–3,800 m.
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. tibetica is one of the smaller members of the genus; plants are 5–15 cm tall, with one to three leaves, which have blades 2–6 cm long by 1–2.5 cm wide. The blade is more-or-less hairy; more so when young. There is a very small ligule, extending to about 0.5 mm, at the junction of the leaf sheath and blade.
In its native habitats, R. tibetica flowers between June and July. 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. Bracts some 2.2–4 cm long enclose the flowers, which are purple or violet and appear just above the leaves.
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, brown-spotted and 3–4 cm long with a three-toothed 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 at 4–5 cm and terminates in three lobes, a narrow upright central lobe, about 1.5–1.7 cm long, forming a hood, and two side lobes, each 1.5–1.8 cm long by 4–5 mm wide. 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, 1–1.3 cm long; two central staminodes are fused to form a lip or labellum, about 1.4–2.5 cm by 0.8–1.8 cm, which is divided into two lobes for more than half its length.
The single functional stamen has a cream anther, about 5–6 mm long, with 3–7 mm long spurs formed from the connective tissue between the two capsules of the anther. The cylinder-shaped ovary is about 1.5 cm long.
Taxonomy
Roscoea tibetica was first described scientifically in 1895 by Alexander Theodorowicz BatalinAlexander Theodorowicz Batalin
Alexander Theodorowicz Batalin , alternatively known as Alexandr Fedorovich Batalin, was a Russian botanist. He was the Chief Botanist and Director of the Imperial Botanical Garden in St...
, a Russian botanist. The specific epithet tibetica refers to the location in which the species was found.
As explained further below, in 2000, plants from areas south and west of 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...
were separated off into a new species, R. bhutanica.
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 platesPlate 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. tibetica was formerly thought to be unique in occurring on both sides of the Brahmaputra River. However, genetic analysis in 2000 showed that plants from the south of the Brahmaputra River, in Bhutan, were distinct from those from the other side of the river, in China. The former were placed in a new species, R. bhutanica. R. tibetica falls into the Chinese clade whereas R. bhutanica belongs to the Himalayan clade, as would be expected from their respective distributions.
The two species are superficially similar, in that they are both small and have a tight group of basal leaves. Young plants of the two species are not easily distinguished, but later it can be seen that while R. bhutanica develops leaves in two opposite rows, R. tibetica retains a rosette of leaves.
Cultivation
Some Roscoea species and cultivars 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. Plants grown at the Royal Botanic Gardens, KewRoyal 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...
as R. tibetica produced small dark purple flowers, one at a time, from early June to July. The plants were noted as being variable (it is not clear whether any were actually what is now R. bhutanica).
For propagation, see Roscoea: Cultivation.