CDFA Pest Prevention Plant Regulation Practice Exam

What method would best determine if a plant is citrus?

1. Counting leaf separations

2. Using ultraviolet light

3. Observation after crushing the plant

4. Holding the leaf to the light

The correct answer is: Holding the leaf to the light

Holding the leaf to the light is an effective method for determining if a plant is citrus due to the unique characteristics of citrus leaves. When you hold a citrus leaf up to the light, you can observe its translucency, which helps distinguish it from other plants. Citrus leaves often have a specific texture and thickness, and the veins may be prominent when illuminated. This visual cue is particularly useful in identifying the species, as many citrus plants share common leaf traits that are visible when backlit. The other methods, while they may provide some information, are not as reliable for specifically identifying citrus. Counting leaf separations could be useful for some species, but it does not specifically point to citrus. Using ultraviolet light may be interesting, but it isn't a standard practice for plant identification and may not yield clear results. Observing the plant after crushing it could reveal oils or scents typical of citrus, but these sensory cues can also vary among different citrus species and may not provide definitive identification.