Plant Identification and Selection
What the exam tests
Plant Identification and Selection tests botanical naming, hardiness zones, site assessment, and matching plant traits to site conditions. Questions often give a site description and ask which plant is most appropriate.
Core rules
- Botanical names: genus capitalized, species lowercase, cultivar in single quotes, for example Acer rubrum 'October Glory'. Common names vary by region.
- USDA hardiness zones reflect average annual minimum temperature; heat tolerance and soil pH are separate limits.
- Assess light (full sun means six or more hours), soil moisture, drainage, pH, exposure to wind, salt, and reflected heat, mature size, and maintenance tolerance before selecting.
- Right plant, right place: check mature height and spread, root volume, utility conflicts, and invasive potential.
- Nursery stock should meet ANSI Z60.1 for size and quality; reject plants with circling roots, weak crotches, or desiccated root balls.
Worked example
A client wants a low-maintenance shrub in full sun, sandy soil at pH 7.6, zone 5a, with no irrigation. Candidate A is Rhododendron 'PJM', which requires acid soil at pH 4.5-6.0, consistent moisture, and afternoon shade; it will show iron chlorosis at pH 7.6. Candidate B is Potentilla fruticosa, which tolerates alkaline soil, drought once established, full sun, and zones 2-6. Select Potentilla. Reasoning: the limiting factors are pH and moisture, not cold hardiness.
Traps
Do not choose by flower color alone. A plant listed as full sun may still scorch in reflected heat. Cultivars within a species can differ in disease resistance and size. Verify hardiness for the cultivar, not just the species. Avoid species listed as invasive in your state.