Heavy Sigh

by Geri Glavis

Title

Heavy Sigh

Artist

Geri Glavis

Medium

Photograph - Photography

Description

Photography by Geri Glavis.
White Orchid Blooms.
The Orchidaceae are a diverse and widespread family of flowering plants with colorful and fragrant blooms, commonly known as the orchid family. Along with the Asteraceae, they are one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species, found in 880 genera.[1][2] Selecting which of the two families is larger is still under debate, as concrete numbers on such enormous families are constantly in flux. Regardless, the number of orchid species equals more than twice the number of bird species, and about four times the number of mammal species. The family also encompasses about 6�11% of all seed plants.[3] The largest genera are Bulbophyllum (2,000 species), Epidendrum (1,500 species), Dendrobium (1,400 species) and Pleurothallis (1,000 species).
The family also includes Vanilla (the genus of the vanilla plant), Orchis (type genus), and many commonly cultivated plants such as Phalaenopsis and Cattleya. Moreover, since the introduction of tropical species in the 19th century, horticulturists have produced more than 100,000 hybrids and cultivars.
A study in the scientific journal Nature [8] has hypothesized that the origin of orchids goes back much longer than originally expected. An extinct species of stingless bee, Proplebeia dominicana, was found trapped in Miocene amber from about 15-20 million years ago. The bee was carrying pollen of a previously unknown orchid taxon, Meliorchis caribea, on its wings. This find is the first evidence of fossilised orchids to date.[8] The extinct orchid M. caribea has been placed within the extant tribe Cranichideae, subtribe Goodyerinae (subfamily Orchidoideae).
This indicates orchids may have arisen 76 to 84 million years ago during the Late Cretaceous. In other words, they may have coexisted with dinosaurs. It also shows insects were active pollinators of orchids then. According to Chase et al. (2001), the overall biogeography and phylogenetic patterns of Orchidaceae show they are even older and may go back roughly 100 million years.[9]
Using the molecular clock method, it was possible to determine the age of the major branches of the orchid family. This also confirmed that the subfamily Vanilloideae is a branch at the basal dichotomy of the monandrous orchids, and must have evolved very early in the evolution of the family. Since this genus occurs worldwide in tropical and subtropical regions, from tropical America to tropical Asia, New Guinea and West Africa, and the continents began to split about 100 million years ago, significant biotic exchange must have occurred after this split (since the age of Vanilla is estimated at 60 to 70 million years).

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March 9th, 2013

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