18 The ground overrun with thorns, denotes those hearers
Mark 4:18 Cross References - Living_Oracles
Matthew 13:22
22 That which fell among thorns, denotes that hearer in whom worldly cares, and deceitful riches, choke the word, and render it unfruitful.
Mark 4:7
7 Part fell among thorns; and the thorns grew up and stifled it, so that it yielded nothing.
Luke 8:14
14 By the ground encumbered with thorns, are meant those hearers who are entangled in the business, and pursuits, and pleasures of life; which stifle the word, so that it brings no fruit to maturity.