Some species of fungi exhibit dimorphism, that is, they can exist as either filamentous or single cells. Dimorphism is common among animal and human pathogens, they are filamentous outside their hosts but assume a yeast-like structure inside the hosts. Most species of fungi have hyphae interrupted at some point by cross-walls called septa and the species are said to be septate. Fungi lacking partitions in their hypha are said to be aseptate, nonseptate, or coenocytic. A major group of fungi, the Basidiomycota, produce specialized structure on their hyphae called clamp connection which ensures their dikaryotic condition.
Some species form swollen cells at the tip of the hyphae called toluroid cells.
Fungal hyphae can form larger structures visible to naked eye such as stroma and sclerotia. Both are just compact mass of somatic hyphae, except that stroma gives rise to fruiting bodies. Some fungi form thick hyphal strands called rhizomorphs. Fungi reproduce by spores, asexually and sexually. Asexual reproduction is repeated several times during the season and results in the production of large number of individuals which is important in the colonization of fungi.