Acotyledon is used to refer to seed plants or spermatophytes that lack cotyledons, such as orchids and dodder.
They depend on mycorrhizal fungi for their early nutrition so are myco-heterotrophs at that stage.
[citation needed] Although some authors, especially in the 19th century and earlier, use the word acotyledon to include plants which have no cotyledons because they lack seeds entirely (such as ferns and mosses),[1][2][3] others restrict the term to plants which have seeds but no cotyledons.
[4] Flowering plants or angiosperms are divided into two large groups.
Conifers and other gymnosperms lack flowers but may have two or more cotyledons in the seedling.