Sessile: adjective; Botany zoology (of a plant or animal structure) attached directly by its base without a stalk or peduncle (Oxford Dictionary).
Dwarf thistles (Cirsium acaule) are also known as Stemless thistles and are a good example of a sessile plant. The only local patch of Dwarf thistles I know is flourishing this year, as their preference is for ‘dry grassy habitats’ on ‘calcareous soils’ (Naturespot website).