Roscoea humeana
Encyclopedia
Roscoea humeana is a perennial herbaceous plant
occurring in the Sichuan
and Yunnan
provinces of China. Most members of the ginger family (Zingiberaceae
), to which it belongs, are tropical, but R. humeana, like other species of Roscoea
, grows in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens.
which occurs in a variety of habitats, such as pine forests, scrub, meadows, grassy and rocky areas, and limestone cliffs, between 2,900 and 3,800 metres in the Sichuan
and Yunnan
provinces of China.
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. humeana, the flowers appear before the leaves are fully grown. Plants are usually 13–25 cm tall, with four to six leaves. Each leaf has a small ligule
, extending to about 2 mm. The blade of the leaf (the part free from the pseudostem) is usually 10–30 cm long by 3–6 cm wide. The leaf sheath is smooth (glabrous), tapering to a point.
In its native habitats, R. humeana flowers between April and July. The stem (peduncle
) of the flower spike is hidden by the leaf sheaths. One to many flowers open together and may be of various colours: purple, violet, yellow, pink or white. The bracts which subtend the flowers are shorter than the calyx.
Each flower has the typical structure for Roscoea
(see the diagrams in that article). There is a long tube-shaped outer calyx, 10–14 cm long with a two-lobed apex. Next the three petal
s (the corolla) form a tube slightly longer than the calyx, terminating in three lobes, an upright hooded central lobe, 3–4 cm long by 2.5–3 cm wide, and two slightly smaller side lobes, 3–3.5 cm long by about 1.5 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 white tinged with purple and 1.5–1.7 cm long; two central staminodes are partially fused at the base to form a lip or labellum, 2–2.5 cm long by about 3 cm wide. The labellum, which is usually smaller than the upper petal, bends backwards and is usually split into two lobes; the sides are wavy.
The single functional stamen has a white anther, about 1.2 cm long, with yellowish-green 6–8 mm long spurs formed from the connective tissue between the two capsules of the anther. The ovary is clylinder-shaped, about 1 cm long, expanding to a 2.5 cm long capsule when seed is set.
and William Wright Smith, two Scottish botanists, in 1916. The specific epithet commemorates David Hume, a member of staff at the Royal Botanic Garden Edinburgh
, who died at the Battle of Mons
in 1914.
.
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. humeana falls into the Chinese clade as would be expected from its distribution. It is closely related to R. cautleyoides
, R. praecox
and R. wardii.
, it flowers in May and June before the leaves have fully expanded. When they have, after flowering, this is one of the largest species of the genus in cultivation. It prefers some shade.
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...
occurring in the 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...
provinces of China. 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. humeana, 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 humeana 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 a variety of habitats, such as pine forests, scrub, meadows, grassy and rocky areas, and limestone cliffs, between 2,900 and 3,800 metres in the 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...
provinces of China.
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. humeana, the flowers appear before the leaves are fully grown. Plants are usually 13–25 cm tall, with four to six leaves. Each leaf has a 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 about 2 mm. The blade of the leaf (the part free from the pseudostem) is usually 10–30 cm long by 3–6 cm wide. The leaf sheath is smooth (glabrous), tapering to a point.
In its native habitats, R. humeana flowers between April 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. One to many flowers open together and may be of various colours: purple, violet, yellow, pink or white. The bracts which subtend the flowers are 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 long tube-shaped outer calyx, 10–14 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 slightly longer than the calyx, terminating in three lobes, an upright hooded central lobe, 3–4 cm long by 2.5–3 cm wide, and two slightly smaller side lobes, 3–3.5 cm long by about 1.5 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 white tinged with purple and 1.5–1.7 cm long; two central staminodes are partially fused at the base to form a lip or labellum, 2–2.5 cm long by about 3 cm wide. The labellum, which is usually smaller than the upper petal, bends backwards and is usually split into two lobes; the sides are wavy.
The single functional stamen has a white anther, about 1.2 cm long, with yellowish-green 6–8 mm long spurs formed from the connective tissue between the two capsules of the anther. The ovary is clylinder-shaped, about 1 cm long, expanding to a 2.5 cm long capsule when seed is set.
Taxonomy
Roscoea humeana was first described scientifically by Isaac Bayley BalfourIsaac Bayley Balfour
Sir Isaac Bayley Balfour FRS FRSE was a Scottish botanist. He was the son of John Hutton Balfour who was also a botanist.-Biography:...
and William Wright Smith, two Scottish botanists, in 1916. The specific epithet commemorates David Hume, a member of staff at the Royal Botanic Garden Edinburgh
Royal Botanic Garden Edinburgh
The Royal Botanic Garden Edinburgh is a scientific centre for the study of plants, their diversity and conservation, as well as a popular tourist attraction. Originally founded in 1670 as a physic garden to grow medicinal plants, today it occupies four sites across Scotland — Edinburgh,...
, who died at the Battle of Mons
Battle of Mons
The Battle of Mons was the first major action of the British Expeditionary Force in the First World War. It was a subsidiary action of the Battle of the Frontiers, in which the Allies clashed with Germany on the French borders. At Mons, the British army attempted to hold the line of the...
in 1914.
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. humeana falls into the Chinese clade as would be expected from its distribution. It is closely related to 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...
, R. praecox
Roscoea praecox
Roscoea praecox is a perennial herbaceous plant occurring in the Yunnan province of China. Most members of the ginger family , to which it belongs, are tropical, but R. praecox, like other species of Roscoea, grows in much colder mountainous regions...
and R. wardii.
Cultivation
Some Roscoea species and cultivars, including R. humeana, 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. R. humeana was described in 1999 as "one of the more popular species" that had been cultivated for many years. When grown at 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...
, it flowers in May and June before the leaves have fully expanded. When they have, after flowering, this is one of the largest species of the genus in cultivation. It prefers some shade.
For propagation, see Roscoea: Cultivation.