'stamenless' originates from the botanical noun 'stamen' (from New Latin 'stamen') combined with the English suffix '-less' meaning 'without'.

'stamen' came into botanical use from Latin 'stamen' (originally meaning 'warp' or 'thread'); the English suffix '-less' derives from Old English 'lēas' meaning 'free from' or 'without', and their combination produced the modern English adjective 'stamenless'.

Originally 'stamen' in Latin meant 'warp' or 'thread' and was later applied to the threadlike male organ of a flower; 'stamenless' therefore developed to mean 'without stamens' and retains that specific botanical sense.