Cullenia exarillata

Cullenia exarillata
Cullenia exarillata fruiting branch
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Malvales
Family: Malvaceae
Genus: Cullenia
Species: C. exarillata
Binomial name
Cullenia exarillata
A.Robyns

Cullenia exarillata is a flowering plant evergreen tree species in the family Malvaceae endemic to the rainforests of the southern Western Ghats in India. It is one of the characteristic trees of the mid-elevation tropical wet evergreen rainforests and an important food plant for the endemic primate, the Lion-tailed Macaque.[1]

Distribution

The species is characteristically found and dominant in the mid-elevation (700 m to 1400 m) tropical wet evergreen rainforests, which has been called the Cullenia exarillata - Mesua ferrea - Palaquium ellipticum type.[2] It occurs from the southern tip of the Western Ghats in Kalakad-Mundanthurai Tiger Reserve and Agasthyamalai hills to Wayanad and Kodagu in the Nilgiri Biosphere Reserve.[3][4][5]

Characteristics

Tall evergreen trees with smooth greyish white bark, flaking in mature trees, with straight boles, frequently buttressed. The branches are horizontal often with series of knob-like tubercles (for cauliflorous attachment of flowers and fruits). The young branchlets and the underside of leaves are covered by golden brown peltate scales. Leaves are simple, alternate, glabrous, shiny green above and covered beneath with silvery or orangish peltate scales.[4] The tubular, hermaphroditic flowers (also covered by golden brown scales) are about 4–5 cm long and cream or pinkish brown in colour. The flowers lack petals and are formed of tubular bracteoles and tube-like calyx, obscurely 5-lobed. The round fruits, about 10–13 cm in diameter and covered with spines, are clustered along the branches. The fruit is a capsule, 5-valved, containing many reddish brown seeds about 4–5 cm long and 2–3 cm wide. In the fruit, the seeds are covered by a fleshy, whitish aril. The fruit dehisces open when mature and dry to release seeds.[6]

Gallery

Breeding system and dispersal

The hermaphroditic (or bisexual) flowers are mainly pollinated by bats (Cynopterus and Rousettus) and arboreal mammals (Lion-tailed Macaque, Brown Palm Civet, Indian Giant Squirrel, Nilgiri Langur, and Indian Giant Flying Squirrel).[7] These mammals and other rodents that visit the flowers such as Dusky-striped Squirrel and Malabar Spiny Dormouse also act as flower predators as they consume a substantial number of flowers.[8] The flowers are also visited by a number of bird species, including Oriental White-Eye, Square-tailed Bulbul, Yellow-browed Bulbul, Brown-cheeked Fulvetta, Common Rosefinch, Kerala Laughingthrush, and White-cheeked Barbet.[9] However, flowers visited by birds tend to be aborted.[10]

Cullenia exarillata is an outcrossing species, producing negligible fruit-set under geitonogamy and no fruit-set under autogamy.[10] The seeds are mechanically dispersed (gravity)[11] as well as by Lion-tailed Macaques over short distances.

Ecology

Cullenia exarillata is a dominant tree species in the mid-elevation tropical rainforests (between 700 and 1,400 m elevation) of the southern Western Ghats.[2] It is also among the most abundant canopy trees in relatively undisturbed mature wet evergreen forests.[12] Individual trees were estimated to produce between 1300 to 26000 flowers (average = 8734) chiefly between February and May, followed by a fruiting peak between May and September, in a rainforest in the southern end of the Western Ghats.[9] As the tree flowers abundantly during the dry season, a period of fruit scarcity in the forest, the flowers attract many diurnal and nocturnal frugivorous mammals and birds, making the tree a possible keystone species in these forests.[9] The flowers are low in nectar but contain fleshy sepals embedded with nectaries which are the main reward for animal visitors.[10] The flowers are eaten by endemic arboreal mammals such as Lion-tailed Macaque[1] and Brown Palm Civet.[13] The seeds and flowers of this species form a major part of the diet (20.7% of annual diet) of Lion-tailed Macaque in mid-elevation rainforests of Silent Valley National Park.[14] A seed predation rate of 45% has been estimated in a wet evergreen forest of the southern Western Ghats, caused by species such as Indian Giant squirrels that feed on unripe fruits (with softer spines) and Lion-tailed Macaques that feed on ripe fruits (with hard spines).[15]

Conservation

The species is endemic to the Western Ghats and has not yet been assessed for the IUCN Red List. The tree may persist in rainforest fragments showing similar levels of flowering and fruit-set, and may even have higher fruit-set in some disturbed sites and on isolated trees.[16] Highly disturbed sites, including plantations where understorey vegetation and canopy trees were removed, have lower density of Cullenia exarillata.[12]

References

  1. 1 2 Kumar, A. (1987) The ecology and population dynamics of the lion-tailed macaque (Macaca silenus) in South India. PhD thesis, Cambridge University, UK.
  2. 1 2 Pascal, J. P. (1988). Wet evergreen forests of the Western Ghats of India: ecology, structure, floristic composition and succession. Pondicherry, India.: Institut Français de Pondichéry.
  3. ↑ "Cullenia exarillata - BOMBACACEAE". www.biotik.org. Retrieved 2016-11-16.
  4. 1 2 Brandis, Dietrich (1906). Indian trees: an account of trees, shrubs, woody climbers, bamboos and palms indigenous or commonly cultivated in the British Indian empire. London.: Archibald Constable and Co. Ltd. (1990 reprint Bishen Singh Mahendra Pal Singh). p. 78. ISBN 81-211-0051-8.
  5. ↑ Gamble, J. S., and C. E. C. Fischer (1915–1935). Flora of the Presidency of Madras, Parts I to XI. (3 volumes). Adlard and Son Limited, London.
  6. ↑ "Cullenia exarillata A. Robyns". India Biodiversity Portal. Retrieved 2016-11-16.
  7. ↑ Devy, M. Soubadra; Davidar, Priya (2003). "Pollination systems of trees in Kakachi, a mid-elevation wet evergreen forest in Western Ghats, India". American Journal of Botany. 90 (4): 650–657. doi:10.3732/ajb.90.4.650. ISSN 0002-9122. PMID 21659160.
  8. ↑ Ganesh, T., and Devy, M. Soubadra (2006). Interactions between non-flying mammals and flowers of Cullenia exarillata Robyns (Bombacaceae), a canopy tree from the wet forests of Western Ghats, India. Current Science 90: 1674-1679.
  9. 1 2 3 Ganesh, T.; Davidar, Priya (1997). "Flowering Phenology and Flower Predation of Cullenia exarillata (Bombacaceae) by Arboreal Vertebrates in Western Ghats, India". Journal of Tropical Ecology. 13 (3): 459–468.
  10. 1 2 3 Ganesh, T.; Devy, M. Soubadra (2000). "Flower Use by Arboreal Mammals and Pollination of a Rain Forest Tree in South Western Ghats, India". Selbyana. 21 (1/2): 60–65.
  11. ↑ Ganesh, T., and Davidar, Priya (2001) Dispersal modes of tree species in the wet forests of southern Western Ghats. Current Science 80: 394-399.
  12. 1 2 Muthuramkumar, S.; Ayyappan, N.; Parthasarathy, N.; Mudappa, Divya; Raman, T. R. Shankar; Selwyn, M. Arthur; Pragasan, L. Arul (2006). "Plant Community Structure in Tropical Rain Forest Fragments of the Western Ghats, India1". Biotropica. 38 (2): 143–160. doi:10.1111/j.1744-7429.2006.00118.x. ISSN 1744-7429.
  13. ↑ Mudappa, D., Kumar, A. and Chellam, R. 2010. Diet and fruit choice of the brown palm civet Paradoxurus jerdoni, a viverrid endemic to the Western Ghats rainforest, India. Tropical Conservation Science 3(3): 282-300.
  14. ↑ Kumar, A. (2013). Lion-tailed macaque. Pages 117-133 in A. J. T. Johnsingh and Nima Manjrekar (editors) Mammals of South Asia, Volume 1, Universities Press, Hyderabad.
  15. ↑ Ganesh, T. (1995). Fruiting patterns among canopy trees and fruit use by vertebrates in a wet evergreen forest of the southern Western Ghats India. PhD Thesis, Pondicherry University, Pondicherry. 149 pages.
  16. ↑ Devy, M. Soubadra (2006). Effects of fragmentation on a keystone tree species in the rainforest of Kalakad Mundanthurai Tiger Reserve, India. Unpublished Report submitted to Rufford Foundation, Ashoka Trust for Research in Ecology and the Environment, Bangalore, India.
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