Warren S. D., Aguilera L. E., Baggett L. S., Directional orientation of reproductive tissue of Eulychnia breviflora (Cactaceae) in the hyperarid Atacama Desert, Revista Chilena de Historia Natural, 2016, 89:10, doi: 10.1186/s40693-016-0060-z
A study of the position of 180 buds and flowers on 40 Eulychnia breviflora plants along a coastal transect. It assesses directions relative to the whole plant and the individual stem. The authors hypothetically link the predominance of the northern side to assimilate availability in illuminated tissues and a possible thermal reward for pollinators. The paper measured neither sugar transport nor the effectiveness of such a reward.