''Scalesia pedunculata'' is a flowering plant species in the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

, growing to a slender tree (20m tall, DBH 20 cm), and found in dense stands on the humid windward coasts of the islands of Santa Cruz, San Cristobal,

Santiago Santiago (, ; ), also known as Santiago de Chile (), is the capital and largest city of Chile and one of the largest cities in the Americas. It is located in the country's central valley and is the center of the Santiago Metropolitan Regi ...

and Floreana in the Galapagos Islands. The Galapagos archipelago lies in the southeast trade wind zone, so that climate and weather are dominated by the moisture-bearing trade winds and the topography of the islands. In general, the windward sides of the islands have a much higher precipitation than the leeward sides. ''Scalesia pedunculata'' is regarded as vulnerable because of human encroachment, invasive introduced plant species such as ''

Cedrela odorata ''Cedrela'' is a genus of several species in the mahogany family, Meliaceae. They are evergreen or dry-season deciduous trees with pinnate leaves, native to the tropical and subtropical New World, from southern Mexico south to northern Argentina ...

'' and ''

Psidium guajava ''Psidium guajava'', the common guava, yellow guava, lemon guava, or apple guava is an evergreen shrub or small tree native to the Caribbean, Central America and South America. It is easily pollinator, pollinated by insects; when cultivated, it ...

'', and grazing by introduced goats. Fires and cutting for fuel are also contributory problems, though the tree's wood is soft, with a large, pithy centre. The inflorescences are capitulae on long peduncles and composed of disc florets only with no

ray florets Asteraceae () is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger fa ...

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...

first collected specimens of this species from Santiago Island ('James Island') in October 1835 on the voyage of the ''Beagle'', and it was later named by his friend

Joseph Dalton Hooker Sir Joseph Dalton Hooker (30 June 1817 – 10 December 1911) was a British botanist and explorer in the 19th century. He was a founder of geographical botany and Charles Darwin's closest friend. For 20 years he served as director of the Ro ...

, who described it as 'frutescens' (becoming a shrub) as he thought that Darwin had made a mistake in calling it a tree, since members of the Daisy family rarely attain such a size. The genus ''Scalesia'' comprises 9 species, with another 5 still unassessed and all endemic to the Galapagos Islands, three of which attain tree size viz. ''Scalesia pedunculata'', ''S. cordata'' and ''S. microcephala'', all three forming dense forests. The name ''Scalesia'' resulted from a blunder by Arnott who named it in honour of "W. Scales Esq., Cawdor Castle, Elginshire" but discovered after publication in 1836 that the name should have read 'Stables', after Scottish botanist William Alexander Stables (1810-21 June 1890), who contributed to botanical literature and was the factor or property manager of

John Campbell, 2nd Earl Cawdor John Frederick Vaughan Campbell, 2nd Earl Cawdor (11 June 1817 – 29 March 1898), was a British politician. Campbell was the son of John Campbell, 1st Earl Cawdor, and Lady Elizabeth Thynne, daughter of 2nd Marquess of Bath. He was known as Vi ...

. The biology of this species has not been well studied. Trees take some 15 years to mature, and stands of woodland usually show a dearth of younger trees growing under the canopy. Entire woodlands collapse when stressed by drought or excessive rain. Shortly after this collapse seedlings start germinating once more, suggesting that the species goes through a natural cycle of build-up and collapse. The first documented collapse of ''Scalesia'' forest occurred between 1935 and 1940, with the cause still not being clear. Next was the collapse in 1982-83, coinciding with an

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event, which brought heavy rain for many weeks, causing roots to rot and strong winds later flattened the entire forest. On Santa Cruz ''Scalesia pedunculata'' grows best at an altitude between 400 – 700 m, a zone which is almost always shrouded in fog, with rain being uncommon. The perennial mists provide moisture to flourishing communities of epiphytes growing on the trunks and branches, with the drops eventually trickling down to ground level and the soil below.

Gallery

ScalesiaSantaCruz2.jpg, LosGemelos.jpg,

References

External links

Gallery of ''Scalesia pedunculata'' images
{{Taxonbar, from=Q14861874 pedunculata Endemic flora of the Galápagos Islands