Roscoea humeana

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Roscoea humeana
Roscoea humeana 060526.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Zingiberales
Family: Zingiberaceae
Genus: Roscoea
Species:
R. humeana
Binomial name
Roscoea humeana
Synonyms [2]

Roscoea humeana f. albaCowley
Roscoea humeana f. luteaCowley
Roscoea humeana f. tyriaCowley
Roscoea sichuanensisR.H.Miau

Contents

Roscoea humeana is a species of flowering plant in the Zingiberaceae family. [2] It is a perennial occurring in the Sichuan and Yunnan provinces of China. [1] 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. [3] It is sometimes grown as an ornamental plant in gardens. [4]

Description

Roscoea humeana is a perennial herbaceous plant. 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. [5] 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. [3]

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. [3]

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 petals (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 stamens (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. [3] [5]

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 cylinder-shaped, about 1 cm long, expanding to a 2.5 cm long capsule when seed is set. [3]

Taxonomy

Roscoea humeana was first described scientifically by Isaac Bayley Balfour and William Wright Smith, two Scottish botanists, in 1916. [1] 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. [6]

Evolution and phylogeny

The family Zingiberaceae 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. [7]

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, their main distributions 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 . [7]

Distribution and habitat

Roscoea humeana 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. [3]

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, Kew, 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. [4]

R. humeana was included in a trial of Roscoea held by the Royal Horticultural Society from 2009 to 2011. It proved hardy (rating H4, i.e. hardy anywhere in the British Isles) and grew successfully. Three forms and one cultivar were given the Award of Garden Merit. [8] The following currently hold the award:

For propagation, see Roscoea: Cultivation.

Related Research Articles

<i>Roscoea</i>

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. The flowers of Roscoea have a complicated structure, in which some of the showy coloured parts are not formed by petals, but by staminodes, sterile stamens which have evolved to become like petals. Some species are grown as ornamental plants in gardens.

<i>Roscoea auriculata</i> Species of plant

Roscoea auriculata is a perennial herbaceous plant occurring in the eastern Himalayas, in Tibet, Bhutan, Nepal and Sikkim. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but R. auriculata, like other species of Roscoea, grows in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens.

<i>Roscoea cautleyoides</i>

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 (Zingiberaceae), to which it belongs, are tropical, but R. cautleyoides, like other species of Roscoea, grows in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens.

<i>Roscoea purpurea</i>

Roscoea purpurea is a perennial herbaceous plant occurring in the Himalayas, particularly Nepal. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but species of Roscoea grow in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens.

<i>Roscoea alpina</i> Species of plant

Roscoea alpina is a perennial herbaceous plant native to the Himalayas. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but R. alpina, like other species of Roscoea, grows in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens.

<i>Roscoea tibetica</i>

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. In 2020, it was proposed that R. tibetica be split again.

<i>Roscoea kunmingensis</i>

Roscoea kunmingensis is a perennial herbaceous plant native to the mountains of China, being found in Yunnan. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but R. kunmingensis, like other species of Roscoea, grows in much colder mountainous regions.

<i>Roscoea capitata</i>

Roscoea capitata is a perennial herbaceous plant native to the Himalayas, being found in Nepal. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but R. capitata, like other species of Roscoea, grows in much colder mountainous regions.

<i>Roscoea forrestii</i>

Roscoea forrestii 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. forrestii, like other species of Roscoea, grows in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens. It was named after George Forrest (1873-1932) who discovered it in Yunnan.

<i>Roscoea tumjensis</i>

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.

Roscoea cangshanensis is a perennial herbaceous plant native to the mountains of China, being found in Yunnan. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but R. canshanensis, like other species of Roscoea, grows in much colder mountainous regions.

<i>Roscoea praecox</i>

Roscoea praecox is a perennial herbaceous plant occurring in the Yunnan province of China. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but R. praecox, like other species of Roscoea, grows in much colder mountainous regions. It is sometimes grown as an ornamental plant in gardens.

<i>Roscoea debilis</i>

Roscoea debilis is a perennial herbaceous plant found in Yunnan, China. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but R. debilis, like other species of Roscoea, grows in much colder mountainous regions.

Roscoea ngainoi is a perennial herbaceous plant occurring in the Ukhrul district of Manipur state, India. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but like other species of Roscoea, R. ngainoi grows in much colder mountainous regions.

Roscoea ganeshensis is a perennial herbaceous plant occurring in Ganesh Himal in central Nepal. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but like other species of Roscoea, R. ganeshensis grows in much colder mountainous regions. It is used as an ornamental garden plant, requiring moisture and shade in the summer.

<i>Roscoea</i> × <i>beesiana</i>

Roscoea × beesiana is considered to be a hybrid between R. auriculata and R. cautleyoides which occurred in cultivation. The flowers are variable: most forms have a pale cream base colour with varying amounts of purple streaking, particularly on the lip or labellum. It was given the Award of Garden Merit by the Royal Horticultural Society in 2011. It is classified as being hardy throughout the British Isles.

<i>Roscoea wardii</i>

Roscoea wardii is a perennial herbaceous plant occurring from eastern Arunachal Pradesh in India to western Yunnan in China. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but like other species of Roscoea, R. wardii grows in much colder mountainous regions.

<i>Roscoea scillifolia</i>

Roscoea scillifolia is a perennial herbaceous plant occurring in Yunnan in China. Most members of the ginger family (Zingiberaceae), to which it belongs, are tropical, but like other species of Roscoea, R. scillifolia grows in much colder mountainous regions. As of 2013, the species is only known in cultivation and may be extinct in the wild.

<i>Cautleya gracilis</i>

Cautleya gracilis is a perennial herbaceous plant in the family Zingiberaceae. It is found in the Himalayas through to south China and Vietnam. It is cultivated as an ornamental garden plant, hardy to a few degrees of frost.

<i>Cautleya spicata</i> Species of plant

Cautleya spicata is a perennial herbaceous plant in the family Zingiberaceae. It is found in the Himalayas through to China (Yunnan). It is cultivated as an ornamental garden plant, hardy to a few degrees of frost.

References

  1. 1 2 3 WCSP (2011), World Checklist of Selected Plant Families, The Board of Trustees of the Royal Botanic Gardens, Kew , retrieved 2011-10-03, search for "Roscoea humeana"
  2. 1 2 "Roscoea humeana Balf.f. & W.W.Sm". Plants of the World Online. The Trustees of the Royal Botanic Gardens, Kew. n.d. Retrieved August 3, 2020.
  3. 1 2 3 4 5 6 Wu, Delin & Larsen, Kai (2000), "Roscoea humeana", in Wu, Zhengyi; Raven, Peter H. & Hong, Deyuan (eds.), Flora of China Vol. 24, Beijing; St. Louis: Science Press; Missouri Botanical Garden, retrieved 2011-10-10
  4. 1 2 Wilford, Richard (1999), "Roscoeas for the rock garden", Quarterly Bulletin of the Alpine Garden Society, 67 (1): 93–101
  5. 1 2 Wu, Delin & Larsen, Kai (2000), "Roscoea", in Wu, Zhengyi; Raven, Peter H. & Hong, Deyuan (eds.), Flora of China Vol. 24, Beijing; St. Louis: Science Press; Missouri Botanical Garden, retrieved 2011-10-01
  6. ↑ Look who is in our garden - Roscoea (Zingiberacae family), Hardy Plant Society, archived from the original on 2011-10-10, retrieved 2011-10-10
  7. 1 2 Ngamriabsakul, C.; Newman, M.F. & Cronk, Q.C.B. (2000), "Phylogeny and disjunction in Roscoea (Zingiberaceae )" (PDF), Edinburgh Journal of Botany, 57 (1): 39–61, doi:10.1017/s0960428600000032 , retrieved 2011-10-03
  8. ↑ Wilford, Richard (2012), "Roscoea on trial", The Plantsman, New Series, 11 (2): 78–85
  9. ↑ "Roscoea humeana f. humeana". RHS. Retrieved 17 February 2021.
  10. ↑ "Roscoea humeana f. lutea'". RHS. Retrieved 17 February 2021.
  11. ↑ "Roscoea humeana 'Stephanie Bloom'". RHS. Retrieved 17 February 2021.

Bibliography

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