Plant Form and Function Plant organs

Plant organs Root system – roots Shoot system – stem and leaves Vegetative organs – (allow to live and grow): roots, leaves, stem Reproduction: flowers, seeds and fruits

Roots Underground, usually equal to shoot system in size Anchors and gives support Absorbs water and minerals Penetrates soil as it grows Root hairs increase surface area Produce hormones

Root organization Root cap – apical meristem, replaced often Zones Cell division – primary meristem, mitosis Elongation – cells lengthen and specialize Maturation – root hairs, fully differentiated

Stems Main axis of plant Support leaves so that leaves are exposed to as much light as possible Node – where leaf is attached Internode – space between nodes Vascular tissue used in transport Can store nutrients and water and conduct photosynthesis

Leaves Photosynthesis Size, shape and texture vary and is used in identification Blade – wide portion of leaf Petiole – stalk, attaches blade to stem Axillary bud – where branch or flower may originate

Leaf anatomy

Plant tissues Meristematic tissue = embryonic Apical meristem – located on tip of stem and roots, primary growth Lateral meristems – secondary growth Woody (non herbaceous), non woody (herbaceous – perennial, dies back in winter)

Woody Stems Primary (length) and secondary (girth of trunks) tissues Secondary tissues form from lateral meristem: vascular cambium – produces secondary xylem (wood) Vascular cambium produces new xylem and phloem each year cork cambium – produces a tough covering that replaces epidermis early in secondary growth 3 distinct areas: Bark – all tissues outside the vascular cambium, living part of tree Contains phloem, can kill a tree if damaged Wood – xylem, almost all is dead when it functions Cork

Secondary growth of trees

Vascular tissue Xylem – water and minerals, roots to leaves Phloem – sucrose and organic molecules (hormones) form leaves to roots Complex tissues – contain 2 or more kinds of cells Both extend from roots to leaves Roots- located in vascular cylinder, stem – vascular bundles, leave – leaf veins

Vascular tissue