The Collaborative International Dictionary of English v.0.48:
Stemless \Stem"less\, a. Having no stem; (Bot.) acaulescent. [1913 Webster]WordNet (r) 3.0 (2006):
stemless adj 1: not having a stem; "stemless glassware" [ant: stemmed] 2: (of plants) having no apparent stem above ground [syn: acaulescent, stemless] [ant: caulescent, cauline, stemmed]