Stems are quite variable
in morphology. They may be elongate and obvious, as pictured below, or
less recognizable if they are compact as in basalbasal:
(adj) at or pertaining to the base, or point of attachment
rosettes, corms, or
bulbs, or as stolons or rhizomes, including those of ferns and aroids.
If your specimen looks like it has a stem, you can use this and other
stem features.
In this tool, the only taxa that actually do lack stems are the duckweeds
(Lemnaceae), the liverworts, and the macroalgaemacroalgae:
(n) (sing. macroalga) large algae; seaweeds
. However, the macroalgaemacroalgae:
(n) (sing. macroalga) large algae; seaweeds
in this tool look plant-like and appear to have stems.