When plant life on the water's surface gets too crowded, many plants that normally grow submerged are nevertheless capable of rising above the water.
許多沈水性植物在水面過度擁擠時，乾脆破水而出，成為挺水植物。林春吉就利用「過長沙」可以泡在水裡，卻也頗為耐旱的特性，將之種在田埂上，成了最漂亮的草皮。