The vascular cambium is a thin layer of dividing cells. What does it produce?
- Heartwood toward the inside and cork toward the outside
- Phloem toward the inside and xylem toward the outside
- Xylem toward the inside and phloem toward the outside
- Bark toward the inside and pith toward the outside
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C. Xylem toward the inside and phloem toward the outside
The cambium lays down new xylem (wood) on its inner side and new phloem (inner bark) on its outer side, which is how the trunk grows in girth. The reversed order is a common mix-up.
Reference: Arborist certification study guide: Tree Biology (meristems)
Which of these is a sign rather than a symptom?
- Dieback of branch tips
- Wilting of the leaves
- A fungal conk on the trunk
- Yellowing between veins
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C. A fungal conk on the trunk
A sign is physical evidence of the causal agent itself, such as a fruiting body, insect, frass or ooze. Wilting, chlorosis and dieback are symptoms: the plant's response.
Reference: Arborist certification study guide: Diagnosis and Plant Disorders (signs and symptoms)
USDA plant hardiness zones are based on which climate measurement?
- Average annual rainfall and snowfall
- Average annual maximum summer temperature
- Average length of the frost-free season
- Average annual extreme minimum temperature
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D. Average annual extreme minimum temperature
The USDA hardiness zone map is drawn from the average coldest winter temperature each year, so it predicts cold survival only. It says nothing about summer heat, rainfall or soil.
Reference: USDA Plant Hardiness Zone Map; arborist study guide: Tree Selection