Corsia

This article is about the plant genus. For the American actor, see Ted de Corsia.
Corsia
Corsia ornata
Corsia ornata from Bird's Head Peninsula, Western New Guinea
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
Order: Liliales
Family: Corsiaceae
Genus: Corsia
Becc.[1]
Type species
Corsia ornata
Becc.
Species

See text.

Corsia is a little-studied plant genus from the monocotyledon family Corsiaceae. It was first described in 1877 by Italian naturalist Odoardo Beccari and contains 25 species, all of which lack chlorophyll and parasitize fungi for nutrition. All 25 species are distributed through New Guinea, the Bismarck Archipelago, the Solomon Islands and Queensland, Australia.

Description

In terms of appearance, the species of Corsia are quite uniform except for the flowers.[2] Chromosome counts are known only from two species: Corsia cornuta and C. clypeata. Both have a diploid number (2n) of 18.[2][3]

Habit

Corsia exist largely underground;[4] only the seldom-formed flower stems develop above ground. The fine, thread-like and hairless root system is weakly branched and whitish, spreading widely just beneath the surface. Several hairless, unbranched and upright flowering stems sprout from a rhizome and are visible above ground. They are usually reddish in color and are 10 to 28 cm (3.9 to 11.0 in) high. The xylem is woody and not perforated.

Leaves

Leaf on a flowering stem of Corsia sp.

The foliage along the stem is evenly distributed, and consists of three to seven broadly ovate pointed leaves. Those on the rhizomes are less developed than the reddish leaves on the flowering stems. Along the stem the leaves grow alternately, at their bases they sheath the stem almost entirely.[4]

Corsia sp. flower

Flowers

The growth of Corsia flowers appears to be triggered by combination of rain and drought, usually by a prolonged rainy season followed by several dry days. The zygomorphic, trimerous, nodding flowers grow singly and are terminal on the stems.[4] The tepals are colored pale red to brownish red, sometimes with a bit of pale yellow and rarely brownish-green.

The six tepals are approximately of the same shape and size, with the exception of the uppermost tepal, termed the labellum, which is considerably larger and usually heart-shaped.[4] The tepals of the species of section Sessilis are 4 to 15 mm (0.16 to 0.59 in) long and 0.5 to 2.5 mm (0.020 to 0.098 in) wide. The tepals of the section Unguiculatis are 3 to 8.5 mm (0.12 to 0.33 in) long and 1 to 3.5 mm (0.039 to 0.138 in) wide. The labellum is about 5 to 25 mm (0.20 to 0.98 in) long and 4 to 22 mm (0.16 to 0.87 in) wide. The labellum encloses the floral bud until its opening, thereby protecting immature floral parts. The labellum is usually simple, but is occasionally bifurcated at the tip of the midrib.

The labellum of Corsia is similar in appearance to the labellum of some orchids, but is not homologous to them;[5] in orchids the labellum is formed from an inner tepal (petal), but in Corsiaceae it forms from an outer tepal (sepal). In Corsia, unlike the orchids, all six stamens are fertile.[5]

Fruit and seeds

Fruits of Corsia ornata
Seeds of Corsia ornata

After pollination (possibly by flies), the peduncles extend and a 3.5 cm (1.4 in) long and slender cylindrical yellowish brown capsule fruit forms. The small dust-like seeds are about 1 to 3.2 mm (0.039 to 0.126 in) long, 0.3 mm (0.012 in) thick and colored pale to dark brown. The seed coat tightly encloses the endosperm and its surface is finely grooved longitudinally.[6] Although the native habitat of Corsia is relatively calm, seed dispersal is presumed to be facilitated by wind (anemochory).[3]

Distribution and habitat

Species of Corsia are generally found in floodplains and mountain forests at altitudes of 400 to 2,700 m (1,300 to 8,900 ft) above sea level. They grow in humus-rich soils in shaded areas of high humidity among decaying leaves.[4]

The center of diversity for the genus is New Guinea. All species are endemic to New Guinea (including the Bismarck Archipelago), the Solomon Islands, and Australia.[7]

Ecology

Like other members of Corsiaceae, Corsia species lack chlorophyll and are thus incapable of photosynthesis. Instead, they are myco-heterotrophs, relying exclusively on parasitizing arbuscular mycorrhizal fungi for nutrition.[8] Myco-heterotrophs were once mistakenly thought to be saprotrophic plants. It is now known that they do not obtain nourishment directly from decaying organic matter, instead they digest the hyphae of saprotrophic fungi with enzymes and absorb the resulting nutrients.[9]

The host species of Corsia, and whether Corsia are even host specific, remains unknown. Corsia are sometimes found growing in association with other myco-heterotrophic plants like Burmannia, Sciaphila, and Cotylanthera tenuis.

Taxonomy

Corsia sp. from the Mount Hagen area of Papua New Guinea

Corsia is classified under the family Corsiaceae of the order Liliales. It is one of the three genera currently classified under Corsiaceae, the other two being Corsiopsis of China and Arachnitis of South America.[9] It differs from the latter two in having several shoots arising from creeping rhizomes.[10]

Corsia was first described in 1877 by the Italian naturalist Odoardo Beccari from specimens from New Guinea. He named it after the Marquis Bardo Corsi Salviati. It was classified under Burmanniaceae by the English botanist George Bentham in 1883 and grouped together with orchids (family Orchidaceae).[11]

In 1938, Fredrik Pieter Jonker separated Arachnitis and Corsia from Burmanniaceae based on their strongly zygomorphic floral characteristics. Kores et al. (1978) also separated Corsia from Burmanniaceae after comparing the chromosome numbers of C. cornuta and C. clypeata (2n = 18) with the rest of Burmanniaceae (2n=32 to 136). Dahlgren & Clifford (1982) tentatively reclassified Corsiaceae as closer to lilies (order Liliales) than to orchids. Cribb et al. (1995) noted the significant differences between Corsia and the only other member of Corsiaceae then - Arachnitis. In 1996, Ibisch et al. challenged the monophyly of Corsiaceae, positing that Arachnitis may actually be more closely related to Orchidaceae than Corsia and recommended the separation of the former into its own family, Arachnitaceae.[11][12]

Corsiopsis was discovered in 1999 by Zhang et al. and became the third genus included in the family Corsiaceae. Zhang also remarked that Corsiopsis seem to be more closely related to Corsia than to Arachnitis. Based on phylogenetic studies and reexamination of previous morphological studies, Neyland & Hennigan (2003) concluded that Corsia is not closely related to Arachnitis. The former probably has closer affinities with Campynemataceae of Liliales, while the latter may be more closely related to Thismia and/or Burmannia of Dioscoreales.[9][11][13] However, Chase et al. (2006) concluded that Arachnitis falls within Liliales while Rudall & Eastman (2002) puts Corsia closer to either Campynemataceae or Thismia. As such, the taxonomic placement of Corsia and Corsiaceae remains problematic though they have been tentatively included in Liliales.[14]

Corsia contains two sections, Unguiculatis and Sessilis, with 25 species. They are listed below along with their distribution ranges:[7][15][16][17]

Section Unguiculatis P.Royen

Section Sessilis P.Royen

See also

Wikispecies has information related to: Corsia
Wikimedia Commons has media related to Corsia.


References

  1. ↑ O. Beccari (1878). Malesia, raccolta d'osservazioni lese e papuano 1. p. 238.
  2. ↑ 2.0 2.1 Paul Kores, David A. White, Leonard B. Thien: Chromosomes of Corsia (Corsiaceae), American Journal of Botany, Vol. 65, No. 5 (May - Jun., 1978), Page. 584-585, ISSN 0002-9122
  3. ↑ 3.0 3.1 C. Neinhuis, P. Ibisch: Corsiaceae, in: K. Kubitzki (Hrsg.): The Families and Genera of Vascular Plants, Vol. 3, Lilianae, p. 200, 1998, ISBN 3-540-64060-6
  4. ↑ 4.0 4.1 4.2 4.3 4.4 Dahlgren, R. M. T.; Clifford, H. T.; Yeo, P. F. (1985). The Families of the Monocotyledons. Berlin: Springer-Verlag. pp. 215–216, 219–220. ISBN 3-540-13655-X.
  5. ↑ 5.0 5.1 P.J. Rudall & A. Eastman (2002). "The questionable affinities of Corsia (Corsiaceae): evidence from floral anatomy and pollen morphology". Botanical Journal of the Linnean Society 138 (3): 315–324. doi:10.1046/j.1095-8339.2002.00024.x.
  6. ↑ J.H. Kirkbride, Jr., C.R. Gunn, and M.J. Dallwitz: Family Guide for Fruits and Seeds, Vers. 1.0, 2006, Retrieved 26 March 2007, Online version
  7. ↑ 7.0 7.1 R. Govaerts (2011). "World Checklist of Corsiaceae". Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet. Retrieved 23 November 2011.
  8. ↑ Christopher G. Morris (1992). Academic Press dictionary of science and technology. Gulf Professional Publishing. p. 529. ISBN 978-0-12-200400-1.
  9. ↑ 9.0 9.1 9.2 Laura S. Domínguez & Alicia Sérsic (2004). "The southernmost myco-heterotrophic plant, Arachnitis uniflora: root morphology and anatomy". Mycologia (The Mycological Society of America) 96 (5): 1143–1151. doi:10.2307/3762096.
  10. ↑ Dian-Xiang Zhang (2000). "Addition to the Flora Reipublicae Popularis Sinicae: the family Corsiaceae". Acta Phytotaxonomica Sinica (in Chinese) 38 (6): 578–581.
  11. ↑ 11.0 11.1 11.2 Ray Neyland & Melissa Hennigan (2003). "A phylogenetic analysis of large-subunit (26S) ribosome DNA sequences suggests that the Corsiaceae are polyphyletic". New Zealand Journal of Botany (The Royal Society of New Zealand) 41 (1): 1–11. doi:10.1080/0028825X.2003.9512828.
  12. ↑ Pierre L. Ibisch, Christoph Neinhuis, & Patricia Rojas N. (1996). "On the biology, biogeography, and taxonomy of Arachnitis Phil. nom. cons. (Corsiaceae) in respect to a new record from Bolivia". Willdenowia 26: 321–332. ISSN 0511-9618.
  13. ↑ P. F. Stevens (2001 onwards). "Liliales". Angiosperm Phylogeny Website. Version 9, June 2008. Retrieved 30 December 2011.
  14. ↑ Michael F. Fay, Mark W. Chase, Nina Rønsted, Dion S. Devey, Yohan Pillon, J. Chris Pires, Gitte Petersen, Ole Seberg, & Jerrold I. Davis (2006). "Phylogenetics of Liliales: summarized evidence from combined analyses of five plastid and one mitochondrial loci". Aliso (Rancho Santa Ana Botanic Garden) 22: 559–565.
  15. ↑ "Corsia". The Plant List Version 1.0. 2010. Retrieved 29 December 2011.
  16. ↑ Barry J. Conn, Roy Banla & Linn Linn Lee. "Plants of Papua New Guinea". Papua New Guinea National Herbarium and the National Herbarium of New South Wales. Retrieved 29 December 2011.
  17. ↑ "Corsia". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government, Canberra. Retrieved 29 December 2011.

Bibliography