Practice question

Bark technically includes all tissues external to vascular cambium: innermost functional secondary phloem transporting photosynthates with sieve elements companion cells albuminous cells plus fibers sclereids, followed by older nonfunctional phloem crushed and periderm comprising phellem cork impregnated suberin waterproofing, phellogen cork cambium meristem and phelloderm secondary cortex photosynthetic sometimes. Primary xylem inside cambium constitutes wood together with secondary xylem; vascular cambium itself lateral meristem not bark tissue. Periderm replaces epidermis in woody stems offering insulation defense against herbivores fire pathogens, lenticels raised pores permit aeration gas exchange, reflecting protective bark composite nature complex.