Concept:Monocotyledonous plants have fibrous roots, narrow parallel-veined leaves, and floral parts in multiples of three, but they generally lack well differentiated sepals and petals.
Explanation:In monocots, the perianth is usually not divided into distinct sepals and petals.
Instead, the floral whorls often appear as similar tepals.
Monocots possess a fibrous root system, so option B is a monocot feature.
They commonly have narrow leaves with parallel venation, so option C is also a monocot feature.
Their floral parts are usually arranged in multiples of three, so option D is a monocot feature.
Therefore, the characteristic not associated with monocots is the presence of well differentiated sepals and petals.
Answer:A. Well differentiated sepals and petals