Roscoea tumjensis
Encyclopedia
Roscoea tumjensis is a perennial herbaceous plant
occurring in the Himalayas, in Nepal
. Most members of the ginger family (Zingiberaceae
), to which it belongs, are tropical, but R. tumjensis, like other species of Roscoea
, grows in much colder mountainous regions.
which occurs in the Himalayas, in central and eastern Nepal
. The type specimen was collected at an altitude of 2,740 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. In the case of R. tumjensis, the flowers appear before the leaves are fully grown. Plants are usually 18–25 cm tall, with four to six leaves. The first three to four consist only of sheaths, which may be marked with purple; the remaining leaves have a blade 4–8 cm by 1.5–4 cm, forming 'ears' (auriculate) at the junction of the blade and sheath. At the junction of the sheath and blade there is also small ligule
, extending to 1–2 mm.
The flower spike (inflorescence) is held within the leaves. The flowers may be of various colours from pale lilac through to bright purple. The bracts which subtend the flowers are much shorter than the calyx.
Each flower has the typical structure for Roscoea
(see the diagrams in that article). There is a tube-shaped outer calyx, with a three-lobed apex. Next the three petal
s (the corolla) form a tube, longer than the calyx, terminating in three lobes, an upright central lobe, about 3 cm long by 1.5–2.5 cm wide, and two narrower side lobes, about 3 cm long by about 0.9–1.4 cm wide. Inside the petals are structures formed from four sterile stamen
s (staminodes): two lateral staminodes form what appear to be small upright petals, which are 1.1–2.2 cm by 0.8–1.3 cm, with a central vein; two central staminodes are partially fused at the base to form a large lip or labellum, 4.5–5.5 cm long by about 3.5–4.5 cm wide. The labellum is split into two lobes at the end for about a quarter of its length.
The single functional stamen has a cream anther, about 6–8 mm long, with 6 mm long spurs formed from the connective tissue between the two capsules of the anther.
The flowers somewhat resemble those of R. humeana
. The leaf blades have auriculate (ear-shaped) bases like those of R.auriculata
, but the latter has white lateral staminodes with a vein which is not central, whereas R. tumjensis has flowers all of the same colour and lateral staminodes with a central vein.
, a botanist at the Royal Botanic Gardens, Kew
, in 1982. The specific epithet relates to location of the type specimen, which was collected by Gardner near Tumje in Nepal in June 1953.
The specimens collected by Gardner were originally labelled as R.purpurea var. auriculata (now R. auriculata
) and R. chamaeleon (now R.cautleyoides
), until Cowley created the new species.
.
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. tumjensis falls into the Himalayan clade as would be expected from its distribution.
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...
occurring in the Himalayas, in 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...
. 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. tumjensis, 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.
Description
Roscoea tumjensis 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...
which occurs in the Himalayas, in central and eastern 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...
. The type specimen was collected at an altitude of 2,740 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. In the case of R. tumjensis, the flowers appear before the leaves are fully grown. Plants are usually 18–25 cm tall, with four to six leaves. The first three to four consist only of sheaths, which may be marked with purple; the remaining leaves have a blade 4–8 cm by 1.5–4 cm, forming 'ears' (auriculate) at the junction of the blade and sheath. At the junction of the sheath and blade there is also small ligule
Ligule
A ligule — is a thin outgrowth at the junction of leaf and leafstalk of many grasses and sedges or a strap-shaped corolla, such as that of a ray floret in plants in the daisy family....
, extending to 1–2 mm.
The flower spike (inflorescence) is held within the leaves. The flowers may be of various colours from pale lilac through to bright purple. The bracts which subtend the flowers are much shorter than the calyx.
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, with a three-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, longer than the calyx, terminating in three lobes, an upright central lobe, about 3 cm long by 1.5–2.5 cm wide, and two narrower side lobes, about 3 cm long by about 0.9–1.4 cm 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 small upright petals, which are 1.1–2.2 cm by 0.8–1.3 cm, with a central vein; two central staminodes are partially fused at the base to form a large lip or labellum, 4.5–5.5 cm long by about 3.5–4.5 cm wide. The labellum is split into two lobes at the end for about a quarter of its length.
The single functional stamen has a cream anther, about 6–8 mm long, with 6 mm long spurs formed from the connective tissue between the two capsules of the anther.
The flowers somewhat resemble those of R. humeana
Roscoea humeana
Roscoea humeana is a perennial herbaceous plant occurring in the Sichuan and Yunnan provinces of China. Most members of the ginger family , to which it belongs, are tropical, but R. humeana, like other species of Roscoea, grows in much colder mountainous regions...
. The leaf blades have auriculate (ear-shaped) bases like those of 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...
, but the latter has white lateral staminodes with a vein which is not central, whereas R. tumjensis has flowers all of the same colour and lateral staminodes with a central vein.
Taxonomy
Roscoea tumjensis was first described scientifically by Elizabeth Jill CowleyElizabeth Jill Cowley
Elizabeth Jill Cowley is a British botanist, who has worked at the Royal Botanic Gardens, Kew. Her interests have included the tropical flora of East Africa and the genus Roscoea.-References:...
, a botanist at the 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...
, in 1982. The specific epithet relates to location of the type specimen, which was collected by Gardner near Tumje in Nepal in June 1953.
The specimens collected by Gardner were originally labelled as R.purpurea var. auriculata (now 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...
) and R. chamaeleon (now R.cautleyoides
Roscoea cautleyoides
Roscoea cautleyoides is a perennial herbaceous plant occurring in the Sichuan and Yunnan provinces of China. The scientific name is also spelt Roscoea cautleoides . Most members of the ginger family , to which it belongs, are tropical, but R. cautleyoides, like other species of Roscoea, grows in...
), until Cowley created the new 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 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. tumjensis falls into the Himalayan clade as would be expected from its distribution.