Editing Brown algae (section)

==Life cycle==
{{more citations needed|section|date=March 2025}}
Most brown algae, with the exception of the [[Fucales]], perform [[sexual reproduction]] through [[sporic meiosis]].<ref>{{Cite book|url=https://books.google.com/books?id=qYTwAAAAMAAJ|title=Introduction to the algae: structure and reproduction|last1=Bold|first1=Harold Charles|last2=Wynne|first2=Michael James|date=1 January 1985|publisher=Prentice-Hall|isbn=9780134777467|language=en|access-date=11 May 2020|archive-date=16 October 2023|archive-url=https://web.archive.org/web/20231016194152/https://books.google.com/books?id=qYTwAAAAMAAJ|url-status=live}}</ref> Between generations, the algae go through separate [[sporophyte]] ([[diploid]]) and [[gametophyte]] ([[haploid]]) phases. The sporophyte stage is often the more visible of the two, though some species of brown algae have similar diploid and haploid phases. Free floating forms of brown algae often do not undergo [[sexual reproduction]] until they attach themselves to substrate. The haploid generation consists of male and female [[gametophyte]]s.<ref>{{Cite book|title=Plant Reproductive Ecology : Patterns and Strategies.|last=Lesley.|first=Lovett-Doust, Jon and|date=1 January 1990|publisher=Oxford University Press|isbn=9780198021926|oclc=437173314}}</ref> The fertilization of egg cells varies between species of brown algae, and may be [[Isogamy|isogamous]], [[Oogamy|oogamous]], or [[Anisogamy|anisogamous]].  Fertilization may take place in the water with eggs and motile sperm, or within the [[oogonium]] itself.

Certain species of brown algae can also perform [[asexual reproduction]] through the production of motile diploid [[zoospore]]s. These zoospores form in plurilocular [[sporangium]], and can mature into the sporophyte phase immediately.

In a representative species ''[[Laminaria]]'', there is a conspicuous [[diploid]] generation and smaller haploid generations. Meiosis takes place within several [[Locule|unilocular]] [[sporangium]] along the algae's blade, each one forming either haploid male or female [[zoospore]]s. The spores are then released from the sporangia and grow to form male and female gametophytes. The female gametophyte produces an egg in the oogonium, and the male gametophyte releases motile sperm that fertilize the egg. The fertilized zygote then grows into the mature diploid sporophyte.

In the order [[Fucales]], sexual reproduction is [[oogamous]], and the mature diploid is the only form for each generation. Gametes are formed in specialized [[conceptacle]]s that occur scattered on both surfaces of the receptacle, the outer portion of the blades of the parent plant. Egg cells and motile sperm are released from separate sacs within the conceptacles of the parent algae, combining in the water to complete fertilization. The fertilized zygote settles onto a surface and then differentiates into a leafy [[thallus]] and a finger-like holdfast. Light regulates differentiation of the zygote into blade and holdfast.

[[File:Saccharina latissima NOAA.jpg|thumb|''[[Saccharina latissima]]'' on a beach.]]