Class Phaeophyceae shine rarrabuwa taxonomic da ake amfani dashi don rukuni na salula masu yawa, galibin algae na ruwa wanda aka fi sani da algae mai launin ruwan kasa. Kalmar "Phaeophyceae" ta fito ne daga kalmomin Helenanci "phaios" ma'ana "launin ruwan kasa" da "phykos" ma'ana "algae". Brown algae suna halin launin ruwan kasa na musamman, wanda ya faru ne saboda kasancewar fucoxanthin pigment a cikin chloroplasts. Ana samun su a cikin ruwan sanyi da ruwan sanyi a ko'ina cikin duniya, kuma suna da girma daga ƙananan sifofi na filamentous zuwa manyan sifofi masu rikitarwa kamar kelps. Brown algae suna da mahimmancin muhalli a matsayin masu samar da farko da kuma matsayin nau'in halittar mazaunin a yawancin halittun ruwa.