Polysiphonia morrowii

{{Short description|Species of alga}}

{{Speciesbox

| image = Icones of Japanese algae (Pl. CXXVII) (8006310599).jpg

| image_caption = Polysiphonia morrowii (fig. 1-8)

| genus = Polysiphonia

| species = morrowii

| authority = Harvey, 1857

| synonyms_ref =

| synonyms =

}}

Polysiphonia morrowii is a species of red algae native to Northeast Asia. It has become an invasive species in Europe, Australia, New Zealand, and South America.{{cite WoRMS

|author=M.D. Guiry

|authorlink=Michael D. Guiry

|year=2010

|id=232563

|title=Polysiphonia morrowii Harvey, 1857

|db=algae

|accessdate=February 6, 2012

}}{{cite web

|url=http://www.algaebase.org/search/species/detail/?species_id=4835

|title=Polysiphonia morrowii Harvey

|author=M.D. Guiry

|publisher=AlgaeBase

|accessdate=February 6, 2012

}}

It is susceptible to infection by the parasitic oomycete Pythium porphyrae{{cite journal|last1=Spencer|first1=M. A.|title=Pythium porphyrae. (Descriptions of Fungi and Bacteria)|journal=IMI Descriptions of Fungi and Bacteria|date=2004|volume=162|issue=Sheet 1617|url=http://www.cabi.org/dfb/abstract/20056401617|accessdate=10 October 2017|language=English|quote=A description is provided for Pythium porphyrae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASES: Red-rot disease, red-wasting disease. HOSTS: Bangia atropurpurea, Callophyllis adhaerens, Polyopes affinis (syn}}