Biology 2217B Chapter : N15__
30 Jan 2014
School
Department
Course
Professor
Document Summary
^ this site has basically all the same notes as our class and more, check it out for lab and http://www. life. umd. edu/classroom/bsci124/main. html exams. Periderm: as the woody stem increases in girth, the epidermis splits and becomes replaced by. 3-layered periderm consisting of: cork cells (phellem, phellogen (meristem, phelloderm. The cork cells are very regular rectangular cells with no intercellular spaces. The cell walls have a layer waterproof suberin on them! Occasionally, the phellogen will produce lens-shaped lenticels instead of cork cells. The loosely packed complementary cells are unsuberised and allow for gas exchange through the bark. Bark = everything external to the vascular cambium = periderm + cortex + phloem. 3- transgenital: angiosperm hardwoods (are actually soft) - multiseriate; gymnosperm softwoods (actually hard) - uniseriate, hardwood vs softwood so only dicots (magnolia/angiosperms) have vessels gymnosperms have resin canals angiosperms can have multiserate. Comes from deciduous trees that drop their leaves every year.
