What describes the growth forms of American frogbit?

American frogbit, scientifically known as Limnobium spongia, is characterized by having two distinct growth forms, which can be described as erect and regular. The erect growth form allows the plant to rise above the water surface, supporting the development of flowers and facilitating the spread of the plant. In contrast, the regular growth form typically refers to its robust floating leaves that lie flat on the water surface, which can be an adaptation to varying water levels.

Understanding these growth forms is essential for effective management and control of the species, as each form may respond differently to environmental conditions and control measures. Recognizing that American frogbit has both erect and regular forms enables better assessment for treatment options and influences decisions on pesticide application or biological control methods.

The other choices describe characteristics that do not accurately encompass the growth forms of American frogbit. For instance, while it does have floating capabilities, it is essential to refer specifically to the erect and regular forms to convey the distinct growth strategies of the plant properly.