An archegonium (pl: archegonia), from the
ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...
''ἀρχή'' ("beginning") and ''γόνος'' ("offspring"), is a multicellular structure or organ of the
gametophyte
A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the ...
phase of certain
plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...
s, producing and containing the
ovum or female
gamete
A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
. The corresponding male organ is called the
antheridium. The archegonium has a long neck canal or venter and a swollen base. Archegonia are typically located on the surface of the plant
thallus, although in the
hornworts they are embedded.
Bryophytes
In
bryophytes and other
cryptogams
sperm reach the archegonium by swimming in water films, whereas in
Pinophyta
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...
and
Angiosperms
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants ...
the
pollen are delivered by wind or animal vectors and the sperm are delivered by means of a
pollen tube.
In the
moss ''
Physcomitrella patens
''Physcomitrium patens'', (synonym: ''Physcomitrella patens'' ) the spreading earthmoss, is a moss (bryophyte) used as a model organism for studies on plant evolution, development, and physiology.
Distribution and ecology
''Physcomitrella p ...
'',
archegonia are not embedded but are located on top of the leafy
gametophore (s. Figure). The
Polycomb protein FIE is expressed in the unfertilized
egg cell (right) as the blue colour after
GUS staining reveals. Soon after
fertilisation the
FIE gene is inactivated (the blue colour is no longer visible, left) in the young embryo.
Gymnosperms
They are much-reduced and embedded in the megagametophytes of
gymnosperm
The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν ...
s. The term is not used for
angiosperms or the gnetophytes ''
Gnetum
''Gnetum'' is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been ...
'' and ''
Welwitschia'' because the megagametophyte is reduced to just a few cells, one of which differentiates into the egg cell. The function of surrounding the gamete is assumed in large part by
diploid cells of the
megasporangium (
nucellus
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the '' nucellus'' (or remnant of the megasporangium), and the ...
) inside the
ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the '' integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the ...
.
Gymnosperms have their archegonium formed after
pollination
Pollination is the transfer of pollen from an Stamen, anther of a plant to the stigma (botany), stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by Anemophily, wind. Pollinating agents can ...
inside female
conifer cone
A conifer cone (in formal botanical usage: strobilus, plural strobili) is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers ...
s (megastrobili).
Brooklyn Botanic Garden
/ref>
References
Plant anatomy
Gymnosperms
Plant reproduction
{{botany
he:מורפולוגיה של הצמח - מונחים#איברים בצמחים פרימיטיביים