What are the two types of mechanical, nonconducting sclerenchyma (Table 5-3)? Which tends to be flexible and useful in wood? Which tends to be brittle and inflexible, useful in “pits” and “stones” that protect seeds?

Table 5-3

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TABLE 5-3 Types of Sclerenchyma Mechanical (nonconducting) sderenchyma Sclereids Fibers Conducting Tracheids More or less isodiametric; often dead at maturity. Long; many types are dead, other types remain alive and are involved in storage. sclerenchyma (tracheary elements) Vessel elements Long and narrow with tapered ends; contain no perfora- tions. Dead at maturity. Found in all vascular plants. Short and wide with rather perpendicular end walls; most contain one or two perforations. Dead at maturity. Found almost exclusively in flowering plants. Among nonflower- ing plants, only a few ferns, horsetails, and gymnosperms have vessels.