Even though floral scent is of major importance for pollinator attraction, it is less investigated than other floral traits. Previous studies suggest the importance of joint exploration of olfactory and visual floral cues to understand plant–pollinator interactions. We investigated flower scents in Collinsia heterophylla, a bee‐pollinated, annual herb a with mixed‐mating system combining self‐ and outcross‐pollination. In Collinsia, floral size and development variation is related to mating system, ranging from large‐flowered mixed‐mating species to small‐flowered self‐pollinated species. However, to our knowledge, flower scent has not been described in any species in the genus. We also studied whether flower‐emitted volatiles were coupled to presence versus absence of a coloured band on the upper lip within a population in C. heterophylla, and if these colour morphs affected pollinator visitation. We performed headspace collections of volatiles in the greenhouse from potted flowering plants, and compared these to controls in the bud stage. Flower‐specific volatiles were highly dominated by terpenoid compounds typical of bee‐pollinated plants, such as β‐myrcene, (Z)‐ and (E)‐ocimene and sesquiterpenes (E)‐α‐bergamotene and β‐sesquiphellandrene. The aliphatic ester methyl hexanoate was also prominent, together with additional esters, whereas methyl cinnamate constituted the only aromatic compound. Floral colour morphs showed no qualitative difference in volatiles, but the coloured morph produced significantly higher quantities for seven of the 26 individual flower compounds. A field experiment performed within a natural population, using behavioural observations and florescent dyes dusted on the flowers, could not detect any differences in pollinator visitation between colour morphs. We conclude that C. heterophylla flowers emit volatile compounds commonly associated with attraction of their most important pollinators. It would be highly interesting to explore the function of floral scent for pollinator attraction and relate floral scent to mating system variation across Collinsia for a better understanding of pollinator influence on floral evolution.

中文翻译：

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混合交配一年生草本Collinsia heterophylla的花香和授粉媒介访问与花色形态的关系

尽管花香对于吸引传粉者至关重要，但与其他花香相比，花香的研究较少。先前的研究表明，联合探索嗅觉和视觉花卉线索对于理解植物与授粉媒介之间相互作用的重要性。我们调查了异花授粉的一年生草本植物Collinsia heterophylla的花香，该花具有混合交配系统，结合了自花授粉和异花授粉。在科林西亚，花的大小和发育变异与交配系统有关，从大花混合交配物种到小花自花授粉物种。然而，据我们所知，该属中的任何物种都没有描述花香。我们还研究了花朵发出的挥发物是否与异叶念珠菌种群中上唇的有色带存在与否相关，以及这些颜色是否影响授粉媒介的探访。我们从盆栽开花植物的温室中进行了顶空挥发物收集，并将其与芽期的对照进行了比较。花特有的挥发物高度受蜜蜂授粉植物典型的萜类化合物的影响，如β-月桂烯，（Z）和（Eocimene和倍半萜（E）-α-佛手柑烯和β-倍半萜烯。脂族酯己酸甲酯与其他酯也很突出，而肉桂酸甲酯是唯一的芳族化合物。花的颜色形态在挥发物上没有定性差异，但是有色的形态对于26种单独的花化合物中的7种产生了明显更高的数量。在自然种群中进行的田间实验，使用行为观察和花朵上撒满的荧光染料，无法检测到颜色变体之间的授粉媒介探访差异。我们得出结论，异叶锦梭鱼花朵散发出挥发性化合物，通常与其最重要的授粉媒介的吸引力有关。探索花香对传粉媒介吸引力的功能，并将花香与整个科林西亚交配系统的变化联系起来，以更好地了解授粉媒介对花的进化的影响，将是非常有趣的。