Roscoea praecox
Encyclopedia
Roscoea praecox 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...

 occurring in the 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...

 province 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. praecox, 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 praecox 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...

 which occurs in both shrubby and grassy habitats in mountains between 2,200 and 2,300 metres in the 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...

 province 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. praecox, the flowers appear before the leaves are fully grown. Plants are usually 7–30 cm tall. The first four or five leaves consist only of a sheath, which has brownish veins. The remaining leaves, which are not developed at flowering time, have a blade, with a very small ligule at the junction of the sheath and blade.

In its native habitats, R. praecox flowers between April and June. 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 may either be hidden by the leaf sheaths or protrude. One to three flowers open together and may be of various colours: purple, violet or white. The bracts which subtend the flowers are 4–6.5 cm long.

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, 3–4.5 cm long with a two-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 (thecorolla) form a tube only just slightly protruding from the calyx, terminating in three more or less equally sized lobes, each around 3 cm long: an upright central lobe and two 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 small upright petals, which are rhombic in shape with a narrower base, 1.7–2.5 cm long; two central staminodes are partially fused at the base to form a lip or labellum, 2.5–4 cm long by 1.5–2 cm wide. The labellum bends backwards and is split into two lobes for more than half its length. It has white markings at its narrowed base.

The single functional stamen has a cream anther with spurs about 7 mm long, formed from the connective tissue between the two capsules of the anther.

Taxonomy

Roscoea praecox was first described scientifically by Karl Moritz Schumann
Karl Moritz Schumann
Karl Moritz Schumann was a German botanist.Dr. Schumann was the curator of the Botanisches Museumin Berlin-Dahlem from 1880 until 1894...

, a German botanist, in 1904. The specific epithet praecox means "early". R. praecox flowers before the leaves have fully developed.

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. praecox 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. 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...

and R. wardii.

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. R. praecox has been grown 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...

, where it flowered between May and July. It does not appear to be as widely cultivated as some other species (e.g. it was not included in the Pacific Bulb Society's information on the genus ), but was part of a Royal Horticultural Society
Royal Horticultural Society
The Royal Horticultural Society was founded in 1804 in London, England as the Horticultural Society of London, and gained its present name in a Royal Charter granted in 1861 by Prince Albert...

 trial of Roscoea in 2007–2011.

For propagation, see Roscoea: Cultivation.
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