Florideophyceae

{{Short description|Class of algae}}

{{Use dmy dates|date=March 2020}}

{{Automatic taxobox

| taxon = Florideophyceae

| image = Haeckel Florideae.jpg

| image_caption = "Florideae" from Ernst Haeckel's Kunstformen der Natur, 1904

| fossil_range = {{long fossil range|Neoproterozoic|present|ref={{cite journal | doi=10.1038/srep21361 | title=Divergence time estimates and the evolution of major lineages in the florideophyte red algae | date=2016 | last1=Yang | first1=Eun Chan | last2=Boo | first2=Sung Min | last3=Bhattacharya | first3=Debashish | last4=Saunders | first4=Gary W. | last5=Knoll | first5=Andrew H. | last6=Fredericq | first6=Suzanne | last7=Graf | first7=Louis | last8=Yoon | first8=Hwan Su | journal=Scientific Reports | volume=6 | page=21361 | pmid=26892537 | pmc=4759575 | bibcode=2016NatSR...621361Y }}}}

| authority = Cronquist, 1960{{Cite journal

| year=1960

| volume=26

| pages=425–482

| author=Cronquist, A.

|title=The divisions and classes of plants

|journal= The Botanical Review

| doi=10.1007/BF02940572

| issue=4| bibcode=1960BotRv..26..425C

| s2cid=43144314

}}

| subdivision_ranks = Subgroups

| subdivision = See text.

}}

Florideophyceae is a class of exclusively multicellular red algae.{{Cite journal|last1=Yoon|first1=Hwan Su|last2=Muller|first2=Kirsten M.|last3=Sheath|first3=Robert G.|last4=Ott|first4=Franklyn D.|last5=Bhattacharya|first5=Debashish|title=Defining the Major Lineages of Red Algae (Rhodophyta)1 |date=April 2006|url=http://doi.wiley.com/10.1111/j.1529-8817.2006.00210.x|journal=Journal of Phycology|language=en|volume=42|issue=2|pages=482–492|doi=10.1111/j.1529-8817.2006.00210.x|bibcode=2006JPcgy..42..482Y |s2cid=27377549 |issn=0022-3646|via=|url-access=subscription}}{{Cite journal |last1=Petroll |first1=Romy |last2=Schreiber |first2=Mona |last3=Finke |first3=Hermann |last4=Cock |first4=J. Mark |last5=Gould |first5=Sven B. |last6=Rensing |first6=Stefan A. |date=2021-07-09 |title=Signatures of Transcription Factor Evolution and the Secondary Gain of Red Algae Complexity |journal=Genes |volume=12 |issue=7 |pages=1055 |doi=10.3390/genes12071055 |doi-access=free |pmc=8304369 |pmid=34356071}} They were once thought to be the only algae to bear pit connections,{{Cite journal | doi = 10.2307/2439535 | last1 = Dawes | first1 = C. J. | last2 = Scott | first2 = F. M. | last3 = Bowler | first3 = E. | title = A Light- and Electron-Microscopic Survey of Algal Cell Walls. I. Phaeophyta and Rhodophyta | journal = American Journal of Botany | volume = 48 | issue = 10 | pages = 925–934 | year = 1961| jstor = 2439535 }} but these have since been found in the filamentous stage of the Bangiaceae.{{Cite book|author=Lee, R.E.|title=Phycology, 4th edition|year=2008|isbn=978-0-521-63883-8|publisher=Cambridge University Press|url-access=registration|url=https://archive.org/details/phycology00robe}} They were also thought only to exhibit apical growth, but there are genera known to grow by intercalary growth. Most, but not all, genera have three phases to the life cycle. In the subclass Nemaliophycidae there are three orders, Balbianiales, Batrachospermales, and Thoreales, which lives exclusively in freshwater.[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7799738/ Complete mitochondrial genomes of six species of the freshwater red algal order Batrachospermales (Rhodophyta)]