Phytophthora lateralis was named by Tucker and Milbrath in 1942. There are no known synonyms. P. lateralis was classified in morphological group V by Stamps et al. (1990); the group includes homothallic species with paragynous antheridia and nonpapillate, proliferating sporangia.
Etymology: refers to the development of chlamydospores in a lateral or sessile position on the hyphae.
Sporangia (average 26–60 µm x 12–20 µm) in water are ovoid, obovoid, or obpyriform. They are non-papillate and persistent, on simple sympodial sporangiophores with internal proliferation. Hyphal swellings are absent. Thin-walled chlamydospores (20–77 µm, average 40 µm) are formed in broth or agar. They are sub-globose to globose or irregular, terminal or intercalary, sometimes positioned laterally or are sessile on hyphae. Considered homothallic, but oogonia normally not seen in culture.