Plant biology, perhaps the oldest branch of science, is driven by a combination of curiosity and need curiosity about how plants work need to apply this knowledge judiciously to feed, clothe, and house a burgeoning human population.

 Morphology (body form)  shoot and root systems inhabit two environments shoot (aerial)  stems, leaves, flowers root (subterranean)  taproot, lateral roots  vascular tissues transport materials between roots and shoots xylem/phloem

A Root –Is an organ that anchors the vascular plant –Absorbs minerals and water –Often stores organic nutrients –Taproots found in dicots and gymnosperms –Lateral roots (Branch roots off of the taproot) –Fibrous root system in monocots (e.g. grass)

(a) Prop roots (b) Storage roots (c) “Strangling” aerial roots (d) Buttress roots(e) Pneumatophores

 A stem is an organ consisting of –Nodes (could be opposite or alternate) –Internodes

Rhizomes (d) Tubers (c) Bulbs Stolons (a) Storage leaves Stem Root Node Rhizome Root

 An axillary bud Is a structure that has the potential to form a lateral shoot, or branch  A terminal bud Is located near the shoot tip and causes elongation of a young shoot Gardening tip: Removing the terminal bud stimulates growth of axillary buds

 The leaf Is the main photosynthetic organ of most vascular plants  Leaves generally consist of Blade Stalk Petiole

 In classifying angiosperms –Taxonomists may use leaf morphology as a criterion Petiole (a) Simple leaf (b) Compound leaf. (c) Doubly compound leaf. Axillary bud Leaflet Petiole Axillary bud Leaflet Petiole

Tendrils Spines Storage leaves Bracts Reproductive leaves. The leaves of some succulents produce adventitious plantlets, which fall off the leaf and take root in the soil.

Three Tissue Systems  dermal tissue epidermis (skin)  single layer of cells that covers entire body  waxy cuticle/root hairs  vascular tissue xylem and phloem  transport and support  ground tissue mostly parenchyma  occupies the space b/n dermal/vascular tissue  photosynthesis, storage, support

 Protects plant from: Physical damage Pathogens H 2 O loss (Cuticle)

 Carries out long-distance transport of materials between roots and shoots  Consists of two tissues xylem phloem

 Includes various cells specialized for functions such as storage, photosynthesis, and support  Pith = ground tissue internal to the vascular tissue  Cortex = ground tissue external to the vascular tissue

 Anatomy (internal structure) division of labor cells differing in structure and function – 5 types parenchyma, collenchyma, sclerenchyma Parenchyma St: “typical” plant cells Fu: perform most metabolic functions Ex: fleshy tissue of most fruit Collenchyma St: unevenly thickened primary walls Fu: provide support but allow growth in young parts of plants Ex: celery Sclerenchyma St: hardened secondary walls Fu: specialized for support; dead Ex: fibers (hemp/flax); slereids (nut shells/seed coats)

 Xylem (water) Xylem dead at functional maturity tracheids- tapered with pits vessel elements- regular tubes  Phloem (food) Phloem alive at functional maturity sieve-tube members arranged end to end with sieve plates WATER-CONDUCTING CELLS OF THE XYLEM Vessel Tracheids Tracheids and vessels Vessel element Pits Tracheids SUGAR-CONDUCTING CELLS OF THE PHLOEM Companion cell Sieve-tube member Sieve-tube members: longitudinal view Sieve plate Nucleus Cytoplasm Companion cell

 Meristems perpetually embryonic tissues located at regions of growth divide to generate additional cells (initials and derivatives) apical meristems (primary growth- length)  located at tips of roots and shoots lateral meristems (secondary growth- girth)

 Primary Growth of Roots apical meristem produces all 3 tissue systems  primary meristems  Protoderm  ground meristem  Procambium  root cap three overlapping zones  cell division  elongation  maturation

Primary Growth in Shoots  apical meristem (1, 7) cell division occurs produces primary meristems  protoderm (4, 8)  procambium (3, 10)  ground meristem (5, 9)  axillary bud meristems located at base of leaf primordia  leaf primordium (2, 6) gives rise to leaves

 Epidermal Tissue upper/lower epidermis guard cells (stomata)  Ground Tissue Mesophyll palisade/spongy parenchyma  Vascular Tissue Veins xylem and phloem

Key to labels Dermal Ground Vascular Guard cells Stomatal pore Epidermal cell 50 µm Surface view of a spiderwort (Tradescantia) leaf (LM) (b) Cuticle Sclerenchyma fibers Stoma Upper epidermis Palisade mesophyll Spongy mesophyll Lower epidermis Cuticle Vein Guard cells Xylem Phloem Guard cells Bundle- sheath cell Cutaway drawing of leaf tissues(a) VeinAir spacesGuard cells 100 µm Transverse section of a lilac (Syringa) leaf (LM) (c) Leaf Anatomy

Lateral Meristems vascular cambium + produces secondary xylem/phloem (vascular tissue) cork cambium + produces tough, thick covering (replaces epidermis) secondary growth + occurs in all gymnosperms; most dicot angiosperms

 The vascular cambium –Is a cylinder of meristematic cells one cell thick –Develops from parenchyma cells  As a tree or woody shrub ages The older layers of secondary xylem, the heartwood, no longer transport water and minerals  The outer layers, known as sapwood Still transport materials through the xylem

 Periderm - protective coat of secondary plant body  cork cambium produces cork cells  cork cells deposit suberin and die  secondary growth commences farther down the shoot  transforms older regions first