Aperture (botany)

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Epilobium pollen has three apertures that are pores Epilobium angust1-4.jpg
Epilobium pollen has three apertures that are pores
The aperture of Lilium pollen is a single sulcus Lilium auratum - pollen.jpg
The aperture of Lilium pollen is a single sulcus

Apertures are areas on the walls of a pollen grain, where the wall is thinner and/or softer. For germination it is necessary that the pollen tube can reach out from the inside of the pollen grain and transport the sperm to the egg deep down in the pistil. The apertures are the places where the pollen tube is able to break through the (elsewhere very tough) pollen wall.

The number and configuration of apertures are often very exactly characteristic of different groups of plants. In Gymnosperms, pollen is usually sulcate, i.e. has a single aperture placed distally compared to the placement of the pollen grains in the meiotic tetrad. [1] The largest clade of angiosperms, the Eudicots, usually have three apertures that run from the proximal side of the pollen grain to the distal side: this apertures are named colpi, and the pollen type of the Eudicots is called tricolpate. [2]

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<span class="mw-page-title-main">Pollen</span> Grains containing the male gametophytes of seed plants

Pollen is a powdery substance produced by flowers of seed plants. It consists of pollen grains, which produce male gametes. Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of gymnosperms. If pollen lands on a compatible pistil or female cone, it germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archaeology, and forensics. Pollen in plants is used for transferring haploid male genetic material from the anther of a single flower to the stigma of another in cross-pollination. In a case of self-pollination, this process takes place from the anther of a flower to the stigma of the same flower.

<span class="mw-page-title-main">Spore</span> Unit of reproduction adapted for dispersal and survival in unfavorable conditions.

In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa.

<span class="mw-page-title-main">Forensic palynology</span> Forensic application of the study of particulate matter

Forensic palynology is a subdiscipline of palynology, that aims to prove or disprove a relationship among objects, people, and places that may pertain to both criminal and civil cases. Pollen can reveal where a person or object has been, because regions of the world, countries, and even different parts of a single garden will have a distinctive pollen assemblage. Pollen evidence can also reveal the season in which a particular object picked up the pollen.

<i>Glossopteris</i> Genus of extinct seed ferns

Glossopteris [etymology: from Ancient Greek γλῶσσα + πτερίς ] is the largest and best-known genus of the extinct Permian order of seed plants known as Glossopteridales. The genus Glossopteris refers only to leaves, within a framework of form genera used in paleobotany. Species of Glossopteris were the dominant trees of the middle to high-latitude lowland vegetation across the supercontinent Gondwana during the Permian Period. Glossopteris fossils were critical in recognizing former connections between the various fragments of Gondwana: South America, Africa, India, Australia, New Zealand, and Antarctica.

<span class="mw-page-title-main">Eudicots</span> Clade of flowering plants

The eudicots, Eudicotidae, or eudicotyledons are a clade of flowering plants mainly characterized by having two seed leaves upon germination. The term derives from Dicotyledons.

<span class="mw-page-title-main">Caytoniales</span> Extinct order of Gymnosperms

The Caytoniales are an extinct order of seed plants known from fossils collected throughout the Mesozoic Era, around 252 to 66 million years ago. They are regarded as seed ferns because they are seed-bearing plants with fern-like leaves. Although at one time considered angiosperms because of their berry-like cupules, that hypothesis was later disproven. Nevertheless, some authorities consider them likely ancestors or close relatives of angiosperms. The origin of angiosperms remains unclear, and they cannot be linked with any known seed plants groups with certainty.

<i>Adoketophyton</i> Extinct genus of spore-bearing plants

Adoketophyton is a genus of extinct vascular plants of the Early Devonian. The plant was first described in 1977 based on fossil specimens from the Posongchong Formation, Wenshan district, Yunnan, China. These were originally named Zosterophyllum subverticillatum; later the species was transferred to a new genus as Adoketophyton subverticillatum. One cladistic analysis suggested that it is a lycophyte, related to the zosterophylls. Other researchers regard its placement within the vascular plants as uncertain.

<i>Normapolles</i>

Normapolles is an extinct angiosperm pollen group that arose in the Cenomanian. Normapolles persisted until the early Oligiocene Epoch but were reduced in diversity by the early Eocene Epoch. Normapolles were widespread in the Late Cretaceous of southern and eastern North America and Europe up to the West Siberian Plain between 56°N and 36°N, collectively referred to as the "Normapolles Province".

<span class="mw-page-title-main">Coryloideae</span> Subfamily of flowering plants

Coryloideae is a subfamily in the woody angiosperm family Betulaceae, commonly known as the birch family, and consists of four extant genera - Corylus L., Ostryopsis Decne., Carpinus L., and Ostrya Scop. These deciduous trees and shrubs are primarily distributed in the boreal and cool temperate zones of the Northern Hemisphere, with the majority occurring in Asia, many occurring in North America and a few species occurring as far south as South America. Synapomorphies such reduced staminate flowers, advanced wood anatomy features, and the presence of spermidines in pollen define the Coryloideae.

<i>Nilssonia</i> (plant) Fossil plant of gondwana supergroup of India

Nilssonia is a genus of fossil foliage traditionally assigned to the Cycadophyta either in Cycadales or their own order Nilssoniales, though the relationships of this genus with the Cycadales have been put into question on chemical grounds.

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<span class="mw-page-title-main">Tupuangi Formation</span> Geological formation in New Zealand

The Tupuangi Formation is a geological formation in New Zealand, only exposed on Pitt Island in the Chatham Islands. It is the oldest exposed sedimentary unit within the archipelago. It was deposited in terrestrial deltaic to paralic conditions during the Cenomanian to Turonian ages of the Late Cretaceous. During this time period the Chatham Islands were attached to Antarctica within the Antarctic Circle, at approximately 70° to 80° south.

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This list of 2013 in paleobotany records new fossil plant taxa that were described during 2013, as well as other significant discoveries and events related to paleobotany that occurred in the year.

This article records new taxa of fossil plants that are scheduled to be described during the year 2021, as well as other significant discoveries and events related to paleobotany that are scheduled to occur in the year 2021.

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References

  1. Doyle, James A. (2005-12-01). "Early evolution of angiosperm pollen as inferred from molecular and morphological phylogenetic analyses". Grana. 44 (4): 227–251. doi: 10.1080/00173130500424557 . ISSN   0017-3134. S2CID   83650545.
  2. Punt, W.; Hoen, P. P.; Blackmore, S.; Nilsson, S.; Le Thomas, A. (2007-01-01). "Glossary of pollen and spore terminology". Review of Palaeobotany and Palynology. 143 (1): 1–81. doi:10.1016/j.revpalbo.2006.06.008. ISSN   0034-6667.

Further reading