Certified Professional Horticulturist (CPH) Practice Exam

Which types of plants are more likely to be injured by intracellular ice formation?

1. Deciduous trees

2. Herbaceous plants

3. Hardy shrubs

4. Container grown plants

The correct answer is: Herbaceous plants

Herbaceous plants are more susceptible to injury from intracellular ice formation due to their structure and composition. These plants are typically characterized by soft, non-woody stems, which contain a high water content and lack the protective adaptations found in woody plants. When temperatures drop, the water inside the cells can freeze, leading to ice crystal formation that can puncture and damage the cell membranes. This process compromises the plant's ability to function and can lead to cell death. In contrast, deciduous trees have adaptations such as the ability to lose leaves and reduce their water content during the winter, which helps mitigate the risk of ice formation within their tissues. Hardy shrubs often have more robust structures and may possess mechanisms like antifreeze proteins or deeper root systems that provide better protection against freezing temperatures. Container grown plants can also face challenges from root exposure to freezing conditions, but their susceptibility to ice formation within cells reflects the specific characteristics of herbaceous plants, making them the most likely to experience injury from this phenomenon.