Pollinium

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A pollinium (pl.: pollinia) is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit. [1] [2] This is regularly seen in plants such as orchids and many species of milkweeds (Asclepiadoideae). Usage of the term differs: in some orchids two masses of pollen are well attached to one another, but in other orchids there are two halves (with two separate viscidia) each of which is sometimes referred to as a pollinium. [1]

Most orchids have waxy pollinia. These are connected to one or two elongate stipes,[ clarification needed ] [3] which in turn are attached to a sticky viscidium, a disc-shaped structure that sticks to a visiting insect. [2]

Some orchid genera have mealy pollinia. These are tapering into a caudicle (stalk), attached to the viscidium. They extend into the middle section of the column.

The pollinarium is a collective term that means either (1) the complete set of pollinia from all the anthers of a flower, as in Asclepiadoideae, (2) in Asclepiadoideae, a pair of pollinia and the parts that connect them (corpusculum and translator arms), or (3) in orchids, a pair of pollinia with two viscidia and the other connecting parts. [1]

Milkweed pollinia are housed within a stigma chamber at the bottom of anther slits of its flower. A pollinating insect often stumbles its legs down the slits and pull up the pollinia as it tries to free its legs; the pollinia can be carried to another flower and dropped down the latter's slits to achieve pollination. However, the insect sometimes fails to retract its legs from the slits and is trapped there until it dies. [4] [5]

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Cephalanthera longifolia, the narrow-leaved helleborine, sword-leaved helleborine or long-leaved helleborine, is a rhizomatous herbaceous perennial plant in the family Orchidaceae. It is native to light woodland, and widespread across Europe, Asia and North Africa from Ireland and Morocco to China. This includes the United Kingdom, Iran, Russia, Kazakhstan, Turkey, Algeria, India, Pakistan, Germany, Italy, France, Spain, Portugal and many other countries.

<i>Asclepias asperula</i> Species of flowering plant

Asclepias asperula, commonly called antelope horns milkweed or spider milkweed, is a species of milkweed native to the Southwestern United States and northern Mexico.

<i>Asclepias meadii</i> Species of flowering plant

Asclepias meadii is a rare species of milkweed known by the common name Mead's milkweed. It is native to the American Midwest, where it was probably once quite widespread in the tallgrass prairie. Today much of the Midwest has been fragmented and claimed for agriculture, and the remaining prairie habitat is degraded.

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<span class="mw-page-title-main">Pollination of orchids</span>

The pollination of orchids is a complex chapter in the biology of this family of plants that are distinguished by the complexity of their flowers and by intricate ecological interactions with their pollinator agents. It has captured the attention of numerous scientists over time, including Charles Darwin, father of the theory of evolution by natural selection. Darwin published in 1862 the first observations of the fundamental role of insects in orchid pollination, in his book The Fertilization of Orchids. Darwin stated that the varied stratagems orchids use to attract their pollinators transcend the imagination of any human being.

<i>Ceropegia ampliata</i> Species of plant

Ceropegia ampliata is a flowering plant in the dogbane family Apocynaceae, native to eastern and southern Africa, including Kenya, Tanzania, Mozambique, South Africa, Eswatini, Botswana, and Madagascar. Common names include bushman's pipe, condom plant, and horny wonder.

References

  1. 1 2 3 Beentje, H.; Williamson, J. (2010). The Kew Plant Glossary: an Illustrated Dictionary of Plant Terms. Royal Botanic Gardens, Kew: Kew Publishing.
  2. 1 2 Hickey, M.; King, C. (2001). The Cambridge Illustrated Glossary of Botanical Terms. Cambridge University Press.
  3. Kull, T.; Arditti, J. (2002). Orchid Biology VIII: Reviews and Perspectives. 8. Kluwer Academic Publishers. p. 127. ISBN   9781402005800.
  4. Theresa Dellinger (August 5, 2016). "Milkweed pollinia". Virginia Tech Insect Collection.
  5. Peter Chen. "Milkweed: Fatal Attractions". nicerweb.com.