Why are Equisetopsida plants described as homosporous?

Equisetopsida plants are described as homosporous because they produce only one kind of asexual spore. In a homosporous life history, these spores are morphologically identical and germinate to produce gametophytes that are typically bisexual, meaning they possess both male and female sex organs.123

While this classification is standard for the group, it is important to note that some species of Equisetum (the sole living genus of Equisetopsida) exhibit a condition known as functional heterospory. In these instances, the spores may be physiologically different, leading to the development of separate male or female gametophytes depending on environmental factors such as temperature. This phenomenon is considered an uncommon variation that may represent an evolutionary step toward the heterosporous condition found in other vascular plants.34