LEC 09 FIELD BOTANY – Lecture 09 Dr. Donald P. Althoff Grasses Part I

Seed-bearing Flowers gymnosperms DICOTS MAGNOLIOPHYTA

Kingdom Division Class ORDERS - FAMILIES - Plantae Magnoliophyta (Anthrophyta) Liliopsida- moncots Cyperales 12 CyperaceaeJuncaceae 3 Juncales grassessedgesrushes

Grasses ______ diverse Grasses: 600 genera between ______________ speciesgeneraspecies Sedges: 70 genera ~4,000 speciesgeneraspecies Rushes: 8 genera ~400 speciesgeneraspecies

Grasslands of the world EQUATOR Tropic of Cancer Tropic of Capricorn

Historically, prairie covered 400,000 mi 2 of North America

____ C 3 plants—all of carbon fixation and photosynthesis happens in _______________ just on the surface of the leaf. C 3 plants include most temperate plants (except many grasses)—more than _____ of all earth’s plants.

____ C 4 plants—carbon fixation and photosynthesis split between the _____________________________________. Warm season grasses  _________ plant group in the short, mixed, and tallgrass prairies

Stomata, CO 2, & Fixation C 3 plants--uses the enzyme rubisco to fix carbon dioxide to RuBP…after fixation is PGAL, a _________________ C 4 plants--do not directly use Calvin cycle and produce immediately a _________________ ____ plants--uses PEP carboxsylase to fix CO 2 at night (example: cacti)

CAM Plants ____________________________ Fixation of CO 2 at night, stored in the form of malate in large vacuoles in the mesophyll cells is available the next day…. Stomata remained ______ during the day!!!

H2O H2O O2O2 CO 2 Calvin cycle

 3 carbon molecule Calvin cycle

 4 carbon molecule before Calvin cycle

 4 carbon molecule before Calvin cycle that is “banked” at night  Calvin cycle completed during the day Night Day

stoma ______ ______ cells Leaf Structure for ___ and ___ plants

Leaf Structure C 3 bundle sheath cells lack chloroplasts C 4 bundle sheath cells __________________ CAM _____________ in mesophyll cells

Enzyme utilized C 3 rubisco C 4 pepco CAM pepco

Optimum Temperature C 3 15 – 25 C__________ C 4 30 – 40 C__________ CAM 35 C__________

oCoC oFoF C 3 Cool season C 4 Warm season CAM o C o F o C o F 35 o C * Approximate optimum (dark shades) and range (light shades) when C 3, C 4, and CAM plants start to grow/conduct photosynthesis efficiently

Growing season What do we mean “cool” vs. “warm” season? Peak period of plant productivity…and flowering cool warm J F M A M J J A S O N D F F F FFF F F F F

Productivity rate (tons/hectare/year) C /- 0.3 C /- 17 CAM low & variable

C 3 Plants - examples Peas Spinach Broccoli Kentucky bluegrass Tall fescue

C 4 Plants - examples Corn Soybeans Tomatoes Indiangrass Buffalo grass Big bluestem Blue grama

Adaptation to the Environment These 3 different “ways” (i.e., C 3, C 4, and CAM)to accomplish photosynthesis illustrate how organisms _________________ to their environment. Each has its advantages and disadvantages C 4 – likely _______ in high light intensity, high temperature, and limited rainfall environments. C 3 –likely _______ in lower light intensity, moderate temperature, and more abundant rainfall environments CAM – likely _______ in extremely arid environments (ferns and cone-bearing plants exhibit this process in addition to many flowering plants like some orchids and lily species)

Characteristics to note for GRASSES Inflorescences Spike vs. spikelets Ligule “design” (see _____________ set) Floret composition (palea, lemma, awns) Seed heads (panicle vs. spike) Fruits (are grains …compared to rushes and sedges )

_______________ = arrangement of flowers on the stem

Spike vs. ________

Seed heads: _______ vs. _______

SPIKELET FLORET seed palea lemma awn

FLORET SPIKELET awn lemma palea