In nature, poinsettias bloom in early March. Research has shown that the flowering process is triggered three months before blooming occurs. In order to make poinsettias bloom in December, florists change the length of the light-dark cycle in September. Given the information and clues above, which of the following is a correct statement about poinsettias?
A) They are short-day plants.
B) They require a light period longer than some set minimum.
C) They require a shorter dark period than is available in September.
D) The dark period can be interrupted without affecting flowering.
E) They will flower even if there are brief periods of far-red illumination during the nighttime.

Question

Quizplus · Accepted Answer

Poinsettias are short-day plants, meaning that they require a specific length of darkness in order to trigger the flowering process. In this case, changing the light-dark cycle in September is necessary to make poinsettias bloom in December, indicating that they require shorter periods of darkness in order to bloom. The other choices are not supported by the information given.

In Nature, Poinsettias Bloom in Early March