CLA CLA Plant Materials & Horticulture 2

Question 1

What is the primary purpose of specifying native plants in a US landscape design?

Accepted Answer

Reduce irrigation need and support local wildlife

Answer

Native plants are adapted to local climate and soil, requiring less supplemental water and providing habitat for native insects and wildlife.

Question 2

A landscape architect specifies Phragmites australis for a wetland restoration. Why might this be a problem?

Accepted Answer

It is an invasive species that outcompetes native wetland plants

Answer

Common reed (Phragmites australis) is an aggressive invasive in US wetlands that forms dense monocultures and reduces biodiversity.

Question 3

Which fertilizer designation indicates the percentage of nitrogen, phosphorus (P₂O₅), and potassium (K₂O) respectively?

Accepted Answer

N-P-K

Answer

The standard fertilizer grade reads N-P-K (nitrogen–phosphorus–potassium), always in that order on the bag label.

Question 4

What is the recommended planting depth for most trees to avoid crown rot?

Accepted Answer

Root flare at or slightly above grade

Answer

Trees should be planted so the root flare is at or just above finished grade to prevent stem and root rot from excess soil moisture.

Question 5

Which of the following grass species is a cool-season turf commonly seeded in the upper Midwest and Northeast US?

Accepted Answer

Kentucky bluegrass

Answer

Kentucky bluegrass (Poa pratensis) is a cool-season turfgrass that thrives in the northern US with cold winters and mild summers.

(CLA) Certified Landscape Architect Practice Test