Master Gardeners Botany for the Gardener Developed by Steve Dubik sdubik@umd.edu Steve.dubik@montgomerycollege.edu 1
Plant cell Basic building block of life. 2
Plant cell - key points Cell membrane Cytoplasm & vacuole Turgor pressure Plasmolysis = Wilting Permanent wilting point 3
Cell walls - Cellulose & lignin 4
Carbon dioxide + Water + Light Energy Simple Sugar + Oxygen 5
Electromagnetic Spectrum 6
Blue light Red light Light Absorption of a Green Leaf 7
Pigments other than Chlorophyll Anthocyanins (reds & purples) Carotenoids (yellows & oranges) 8
Photosynthesis 6CO 2 + 6H 2 O + Light Energy C 6 H 12 O 6 + 6O 2 Produces food Energy is stored Occurs in cells that contain chloroplasts Oxygen is released Water and carbon dioxide is used Occurs under light energy 9
Respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Heat Uses food for plant energy Energy is released Occurs in all living cells Oxygen and food is used Carbon dioxide is produced Occurs in the dark as well as light Both processes are temperature dependent 10
Benefits of moderate stress Moderately stressed trees are often most resistant to pests. 11
Benefits of moderate stress Moderate nutrient and moisture stress does not impact photosynthesis but does limit growth, making carbohydrates available to support other processes such as defense chemicals. 12
Cross-section of a Leaf Cuticle Cutin Low CO 2 Transpiration High CO 2 13
Water transport 14
Vascular System Xylem and Phloem Key Distinctions Xylem translocates water and minerals upwards 15
Vascular System Xylem and Phloem Key Distinctions Phloem translocates food materials primarily downward 16
Cross Section of a Herbaceous Stem Epidermis Cortex Pith Primary phloem Primary xylem 17
Vascular Bundles Phloem tissue Xylem tissue 18
Cross-section of a Woody Branch Sapwood 19
Cross-section of a Woody Branch Springwood Summerwood Annual Growth Rings 20
Structure of a Woody Stem 21
Growth in a Woody Stem through Successive Seasons Blue - xylem tissue Gold - vascular cambium Pink - phloem tissue 22
Parts of twig Stem of a woody dicotyledon: Prunus sp. 23
Bud Scales Bud scales on Oak (Quercus sp.) 24
Leaf Scars Vascular Bundle Scars 25
Stem Structure Review Vascular bundle trace = Vascular bundle scar Lateral bud = Axillary bud Terminal bud scale scar 26
Root systems 27
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Quick Facts Most tree roots are located in the top 6 to 24 inches of the soil. Most tree roots occupy an area two to four times the diameter of the tree crown. Roots grow beyond the drip line. Few roots grow deep in the soil they do not mirror the crown. Few roots grow deeper than 3 to 7 feet. Roots obtain water, oxygen and minerals from soil. They do not grow toward anything or in any particular direction. - they grow where the water is. 30
Root Distribution 31
Quick Facts Almost half the sugars in the leaves are used and lost through root growth. Root can grow any time of the year. One of the biggest killers of urban trees is soil compaction. Soil compaction restricts water and oxygen uptake by roots, and is associated with roads, parking lots, foot traffic, construction machinery, poor soil preparation, and a host of other factors. Overwatering causes the soil pore (air) spaces to fill with water and restrict oxygen uptake. 32
Monocots & Dicots (Eudicots) 33
Dicots a.k.a. - Eudicots Cotyledons 2 Leaves mostly net veined Vascular bundles borne in a ring Floral parts borne 4 s or 5 s Monocots Cotyledon 1 Leaves mostly parallel veined Vascular bundles scattered Floral parts borne 3 s Vascular cambium lacking 34
Questions Developed by Steve Dubik sdubik@umd.edu / 301-590-2838 steve.dubik@montgomerycollege.edu 240-567-7803 35