A hypha is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium.
Hyphae of Penicillium
Hyphae growing on tomato sauce (the pale oblong objects to the side are rice grains)
The oomycetes, or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexua
Sexual structures (only oogonia, antheridia not shown) of Saprolegnia.[citation needed]
Pythium sp. (Peronosporales), which causes pythiosis in animals, under microscope.
Symptom of late blight (P. infestans, Peronosporales) on the underside of a potato leaf.
Albugo candida (Albuginales) on shepherd's purse (Capsella bursa-pastoris, Brassicales).