TYPES OF STEMS n 1. Crown-highly compressed stem n 2. Tillers-primary lateral stem n 3. Stolons-above ground, secondary lateral stem n 4. Rhizomes-below ground, secondary lateral stem n 5. Culm -stem of grass plant, flowering

Basic Plant Structure

apical meristem

Basic Plant Structure apical meristem Leaf Blade (lamina) Petiole

Basic Plant Structure apical meristem node Leaf Blade (lamina)

Basic Plant Structure apical meristem internode node Leaf Blade (lamina)

Basic Plant Structure apical meristem internode node axillary bud Leaf Blade (lamina)

Basic Plant Structure apical meristem internode node axillary bud primary root secondary, branch root Leaf Blade (lamina)

Basic structure, compressed

The Grass Plant

Tillers n Develop from axillary buds n Usually live less than 1 year n Some produced in spring, important for summer survival n Some produced in fall, usually die late spring, early summer n Enhanced by mowing n Some grasses only produce tillers - Bunch grasses n Tillers represent the future for bunch grasses n Intravaginal shoot development

Stolons n Grow along soil surface, aboveground n Live one or more years n Produced in fall for cool season grasses n In spring for warm season grasses n Extravaginal shoot development, involving rupture of surrounding sheath tissue n Stolons may branch profusely n These grasses are sod-forming

Rhizomes n Grow underneath the soil, an underground version of the stolon n Determinate (KBG) are short and non-branching n Indeterminate (Berm.) are long and multi-branched. n Provides sod strength n Winter survival n Wear tolerance n Major storage organ for long-term survival

The Crown n Most important part of plant n Place where new shoots develop n Highly compressed series of nodes n Where all the leaves are attached n Where all the axillary buds are located n Where tillers, rhizomes, stolons originate n Highly protected!

The Crown Crown

The Phytomer Unit –The smallest complete unit containing all the necessary parts of the turf plant: »Node »Internode (stem piece) »Axillary bud at node »Root Primordia at node –A phytomer can survive on its own - this is the basis for vegetative propagation.

CULM - The Flowering Shoot n Phases: –a. Maturation - plant must be old enough, big enough –b. induction »1. Vernalization - cold treatment - take place in growing point - reversible. Cool season grasses »2. Photoperiod - takes place in leaves n cool season = long day n warm season = short day –c. Initiation - crown changes from vegetative to flowering - elongation occurs –d. Development - seed head formation

CULM n Disadvantages: –b. drains food reserves –c. death of shoot –d. mowing is difficult –e. affects play, Poa annua –a. unsightly

II. LEAVES n The leaves are the major site of food production. They contain the green pigment chlorophyll. Photosynthesis is the process that produces carbohydrates. Leaves originate at the crown, both the apical meristem and axillary buds. n What is a meristem? n Intercalary meristem?

II. LEAVES (continued) n 1. Components –a. blade –b. sheath –c. collar –d. ligule –e. auricle n 2. Vernation n 3. Leaf #/shoot –a. same for given environ, usually 5-10/shoot

Leaf Anatomy Midrib Veins Xylem Phloem Epidermis

Roots “If you can grow roots, the shoots will take care of themselves” n Anchorage n Absorption of water and nutrients n Storage n Primary, or seminal develop from seed, short lived n Adventitious roots develop later and then continuously from the nodes. Nodal roots.

Regions of the Root n Root Cap n Meristem n Region of Elongation n Region of Differentiation - where root hairs develop, and also vascular tissue n Region of Maturation, where suberization occurs. Roots become more rigid. Lateral roots form

Root Systems n Multibranching and fibrous n Turf roots not major storage organs n Source of plant hormones, cytokinins n Usually 4-18 inches deep n Warm-season grasses have larger diameter, deeper roots than cool-season grasses

Root Hairs Stele Root Cap Meristem Elongation Differentiation Maturation

Restrictions to Rooting n High soil temperatures n Acidic soils, aluminum toxicity n Lack of oxygen n Salts n Pesticides n Improper mowing height, frequency n Excessive N, deficient K nutrition n Excessive thatch n Improper irrigation n Flowering

Root Longevity n Death and replacement is continuous n Some roots last 2 years (KBG) n Seasonal root growth: cool-season best in spring and fall, warm-season best in summer. Spring root decline in WS, summer root decline in CS.

Temperature Effects n 4. Cool Season –a. Growth Curve –b. Temperature: »Min - 33 o F »Opt o F »Max - 80 o F n 5. Warm Season –a. Growth Curve –b. Temperature »Min - 40 o F »Opt o F »Max o F

WARM SEASON GRASSES n COMMON n Bahia n Barnyard Grass n Bermuda n Centipede n Dallisgrass n Goosegrass n Japanese Lawngrass (Zoysia) n Large Crabgrass n Smooth Crabgrass n St. Augustine n Yellow Foxtail n SCIENTIFIC n (Paspalum notatum) n (Echinochloa crusgalli) n (Cynodon dactylon) n (Eremochloa ophiuroides) n (Paspalum dilatatum) n (Eleusine indica) n (Zoysia japonica) n (Digitaria sanguinalis) n (Digitaria ischaemum) n (Stenotaphrum secundatum) n (Setaria glauca)

COOL SEASON GRASSES n COMMON n Annual Bluegrass n Kentucky Bluegrass n Rough Bluegrass n Colonial Bentgrass n Creeping Bentgrass n Italian Ryegrass n Orchardgrass n Perennial Ryegrass n Quackgrass n Red Fescue n Tall Fescue n SCIENTIFIC n (Poa annua) n (Poa pratensis) n (Poa trivialis) n (Agrostis tenuis) n (Agrostis palustris) n (Lolium multiflorum) n (Dactylis glomerata) n (Lolium perenne) n (Agropyron repens) n (Festuca rubra var. rubra) n (Festuca arundinacea)

General Growth Curves Jan. Mar May July Sept Nov. Growth Warm Season Cool Season

Regions of Adaptation

Cool Humid Warm Arid Warm Humid Tropical Transition Cool Humid Cool Arid

PHYSIOLOGY n 1. Two processes required for growth: –a. photosynthesis –b. Respiration n Growth = photosynthesis - respiration

PHYSIOLOGY n Photosynthesis –manufactures food –H 2 O + CO 2 + light = sugar + O 2 + water –Sugars used to build new tissue, and to maintain existing tissue through respiration. –Sugars stored in crowns, stolons, rhizomes and roots.

Photosynthesis n Cool season grasses, C3, o n Warm Season grasses, C4, o C4 plants can utilize high light better

C3 vs. C4 Species Light Intensity Photosynthesis C3 species C4 species

Respiration n Produces energy to build tissue, maintain existing tissues n Carbohydrates broken down sugar + O 2 = CO 2 + H 2 O + energy

PHYSIOLOGY n Warm season - respire mainly in dark n Cool season - respire in dark and light. This is called "photorespiration” n Comparison Photorespiration Photosynthetic rate rate rate rate C3 High Low C4 Low High

Environmental Effects n Photosynthesis slightly affected by temperature. n Respiration affected greatly by temperature. As temperature increases, so does respiration. –Accumulate food in cool temperatures –Photosynthesis > respiration Deplete food in high temperatures Deplete food in high temperatures –Respiration > photosynthesis EX: Summer fertilization of cool season grasses EX: Summer fertilization of cool season grasses

PHYSIOLOGY n Accumulate food when growth is slow. » eg. Fall fertilization n Deplete food when growth is fast »eg. spring root die back »eg. Recovery from environment or pest »eg. Seed head production