Question

what do poinsettias require for flower production?
a. a long day
b. a short day
c. none of the above
d. no light at all

Explanation:

Poinsettias are short - day plants. Short - day plants flower when the day length is shorter (and night length is longer) than a certain critical period. Poinsettias require short days (long nights) to initiate flower production. Option a is incorrect as long days are not required for poinsettia flowering. Option d is incorrect as light is necessary for photosynthesis and plant growth, and no light at all would not allow flower production. Option c is incorrect because option b is correct.

Answer:

b. A short day