The developing Narcissus pseudonarcissus plant (daffodil) is shown to face towards a preferential direction (east, south, west, or north, in that order) before flowering. Said directionality is accomplished by stem bending, a phototropic response mechanism, which is sensitive to partial blocking of the available sunlight from the local environmental. Polar distribution diagrams show that with partial environmental shading from the north, east, south, or west, the developing daffodil plant always excludes facing in that direction, to absorb maximum available sunlight. Stem buckling experiments, equivalent to stem bending, are presented measuring the Euler buckling exponent n = − 2.1 for daffodil flower stems, in good agreement with theory, r = 0.99. Individual flower stems are capable of generating 2–3 lbf of vertical force, which explains the plants ability to penetrate frozen ground cover. Results from 193 daffodil flower stems are presented, showing that 61.7% face East [95% CI 54–70%], 17.1% face South, 15.0% face West, and only 6.2% face North [95% CI 2–10%], depending strongly on the partial shading effect of the surrounding environment.

中文翻译：

---

发育中的水仙植物的光敏“触发器”特性（水仙向光性）

发育中的伪水仙植物（水仙花）在开花前显示出朝向优先方向（按东、南、西或北的顺序）。所述方向性是通过茎弯曲来实现的，这是一种向光响应机制，它对局部环境中可用阳光的部分阻挡很敏感。极地分布图显示，在北、东、南或西的部分环境阴影下，发育中的水仙花植物总是排除朝那个方向的朝向，以吸收最大的可用阳光。茎屈曲实验，相当于茎弯曲，测量了水仙花茎的欧拉屈曲指数 n = - 2.1，与理论非常吻合，r = 0.99。单个花茎能够产生 2-3 lbf 的垂直力，这解释了植物穿透冰冻地被植物的能力。展示了 193 朵水仙花茎的结果，显示 61.7% 朝东 [95% CI 54–70%]，17.1% 朝南，15.0% 朝西，只有 6.2% 朝北 [95% CI 2–10%] ，强烈依赖于周围环境的局部阴影效果。