سؤال قراءة ستيب محلول — فهم التفاصيل (تدريب 6157)

stay upright because each of their cells is filled with water under pressure. This water pressure or “turgor”-makes them rigid like a well-inflated football. But such plants wilt when their water supply fails. Vascular plants with lignin, however, can survive dry periods and can grow far bigger than any herb. Many herbs have some lignin that toughens them here and there, yet they remain primarily herby. True wood requires special architecture the lignin-toughened cells are very well organized and arranged. Herbs are plants that are …………….