Certified Professional Horticulturist (CPH) Practice Exam

Which type of grass must be planted by vegetative means because its seed does not produce plants that are true to type?

1. Tall Fescue

2. Kentucky Bluegrass

3. Zoysia

4. Perennial ryegrass

The correct answer is: Zoysia

Zoysia grass must be planted by vegetative means because its seed does not consistently produce plants that are true to type. This characteristic is important when considering the propagation of grass species. Zoysia's seed can be genetically variable, leading to inconsistent traits in the offspring, which is why vegetative propagation methods, such as sod, plugs, or sprigs, are preferred. This ensures that the new plants maintain the desirable characteristics of the parent plant, such as growth habit, disease resistance, and texture. In contrast, the other grass types listed can be reliably grown from seed, producing plants that exhibit the expected traits of the species when grown from seed. This ability to propagate successfully from seed makes them suitable for various landscapes and maintenance practices. Understanding these propagation methods is crucial for horticulturists in making informed decisions about lawn establishment and maintenance.