{ Epidermis. { { { Simple hairs. { { Many-celled hairs. { { Branched hairs, often stellate. Epidermal { Trichomes. { Clustered, tufted hairs. System. ····{ { Glandular hairs. { { Root hairs. { { Prickles. { { Guard cells of stomates. { Spiral vessels. { Pitted vessels. { Scalariform vessels. { Xylem (wood). { Annular vessels. { { Tracheides. { { Wood fibers. { { Wood parenchyma. Fibrovascular { System. ····{ Cambium (fascicular). { { { Sieve tubes. { Phloem (bast). { Bast fibers. { Companion cells. { Bast parenchyma. { Cork. { Collenchyma. { Cortex.····{ Parenchyma. { { Fibers. { { Milk tissue. { { Pith-ray.··{ Parenchyma. { { Intrafascicular { Stem and root. { cambium. { { Pith.······{ Parenchyma. { { { Sclerenchyma. { { Fundamental { { Bundle-sheath. System. ····{ { { { Endodermis. { { Leaves. { Palisade tissue. { { Spongy parenchyma. { { Reproductive Organs (mainly fundamental). =714. Physiological Classification of Tissues.= _Formative Tissue._ Thin-walled cells composing the meristem, capable of division and from which other tissues are formed. _Protective Tissue._ _Tegumentary System._—Epidermis, periderm, bark protecting the plant from external contact. _Mechanical System._—Bast tissue, bast-like tissue, collenchyma, sclerenchyma, afford protection against harmful bending, pulling, etc. _Nutritive Tissues._ _Absorptive System._—Root hairs and cells, rhizoids, aerial root tissue, absorptive leaf glands, absorptive organs in seeds, haustoria of parasites, etc. _Assimilatory System._—Assimilating cells in leaf and stem.