n.向日性；屈日性

Sunflowers always turn with the sun because of their heliotropism. 向日葵的向光性使它總是隨著太陽的方向而移動。

Heliotropism A form of phototropism in which flowers move to point toward the sun, tracking it as it moves across the sky. 向日性：趨光性的一種類型，植物的花在一天內(nèi)朝向太陽，并隨著日光照射的方向而轉(zhuǎn)移方位。

Recent explanations for heliotropism of sunflower 葵花向陽原因新解析

negative heliotropism 背日性,負向日性

Flower heliotropism 花向日性