OrchidsValentina Gomez

Period 6

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Statistics There are over 17,000 known species of

orchids. They may live on trees, or on the ground. Many orchids depend on a certain species

for pollination. Some will only sprout seeds in the presence

in a particular type of soil fungus. Most highly prized of all flowers. May live all over the world.

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Pollination•”Many orchids deceive their pollinators by advertising

nonexistent rewards. Bee orchids (genus Ophrys) and certain tropical orchids have flowers that mimic bees or wasps. Their scents stimulate male bees to attempt sexual union (copulation) with them. During this pseudo-copulation, pollen is transferred to the stigma of the plants from bees. Corybas orchids mimic the smell of mushrooms. These attract flies that normally lay their eggs on mushrooms. Similarly, Bulbophyllum flowers smell of carrion (rotting flesh) and attract carrion flies.”

• “Most orchids are pollinated by insects, such as bees, butterflies, and moths. An insect in search of nectar or another reward enters the flower, where it comes into contact with the viscidum, a sticky disk connected by a stalk to the pollinia.”

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Orchid Families Apostasioideae Cypripedioideae Epindroideae Orchidoideae Vanilloideae

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Apostasioideae “The Apostasioideae are generally considered a basal

lineage within the orchids based on molecular data and flower structure. All other orchid subfamilies with the exception of the Cypripedioideae are monandrous (possessing a single stamen), however Apostasiod orchids have 3 stamens.”

“As with all basal or 'primitive' groups, extant species within Apostasioideae do not represent direct ancestors of the other subfamilies, they simply share the same common ancestor. However, by having followed a separate evolutionary pathway from the other orchids extant Apostasioid orchids may allow us to make inferences about features present in that common ancestor.”

Cypripedioideae “Lady's slipper orchids, lady slipper orchids or slipper

orchids are the orchids in the subfamily Cypripedioidea, which includes the genera Cypripedium, Mexipedium, Paphiopedilum, Phragmipedium and Selenipedium. They are characterized by the slipper-shaped pouches (modified labellums) of the flowers – the pouch traps insects so they are forced to climb up past the staminode, behind which they collect or deposit pollinia, thus fertilizing the flower.”

“Paphiopedilums are found in the tropical forests of southeast Asia reaching as far north as southern China. Paphiopedilum is quite easy to cultivate and therefore is popular among orchid enthusiasts. In fact, overcollecting of this genus has caused some problems in its original habitat.”

Epindroideae “Epidendroideae is larger than all the other orchid

subfamilies together, comprising more than 15,000 species in 576 genera. Most Epidendroid orchids are tropical epiphytes, typically with pseudobulbs. There are, however a few terrestrials and even a few myco-heterotrophs, which are parasitic upon mycorrhizal fungi.”

“Most epiphytic seed plants and ferns are found in tropical and subtropical rainforests because they need high humidity to survive. The areas which most epiphytes grow are the mountain rainforests.”

Orchidoideae Typically contain the orchids with a single

(monandrous), fertile anther which is erect and basitonic.

The subfamily Orchidoideae and the previously recognized subfamily Spiranthoideae are considered the closest allies in the natural group of the monandrous orchids because of: a shared terrestrial habit sectile (capable of being severed) or

granular pollinia erect anthers.

Vanilloideae The subfamily Vanilloideae consists of 15 genera and

about 180 species, belonging to the tribes Pogonieae and Vanilleae,

Their distribution is pantropical, throughout Asia, Australia and the Americas.

Lindley (1836) and even Garay (1986) used to treat it as a separate family Vanillaceae. But their single, incumbent anther and poorly organised pollinia led to their recognition as at best a subgroup of monandrous orchids. But, from a molecular point of view, this clade is rather a sister to subfamily Epidendroideae and subfamily Orchidoideae in the Orchidaceae, and thus it is today also considered a subfamily.

Bibliography Slides 1 and 2:

Bower, Erica. "Orchid." Animal and Plant Anatomy. Marshall Cavendish Digital, 2011. Web. 09 May 2011.

<http://www.marshallcavendishdigital.com/articledisplay/1/984/10118>

Slides 3 -9 "Orchidaceae." Wikipedia, the Free

Encyclopedia. Wikipedia. Web. 10 May 2011. <http://en.wikipedia.org/wiki/Orchidaceae>