Am J Bot. 1997 Dec;84(12):1701.
Sarracenia purpurea L. (northern pitcher plant) is an insectivorous plant with extrafloral nectar that attracts insects to a water-filled pitfall trap. We identified and quantified the amino acids in extrafloral nectar produced by pitchers of S. purpurea. Nectar samples were collected from 32 pitchers using a wick-sampling technique. Samples were analyzed for amino acids with reverse-phase high-performance liquid chromatography with phenylisothiocyanate derivatization. Detectable amounts of amino acids were found in each of the 32 nectar samples tested. Mean number of amino acids in a nectar sample was 9 (SD = 2.2). No amino acid was detected in all 32 samples. Mean amount of amino acids in a nectar sample (i.e., amount per wick) was 351.4 ng (SD = 113.2). Nine amino acids occurred in 20 of the 32 samples (aspartic acid, cysteine, glutamic acid, glycine, histidine, hydroxyproline, methionine, serine, valine) averaging 263.4 ng (SD = 94.9), and accounting for ~75% of the total amino acid content. Nectar production may constitute a significant cost of carnivory since the nectar contains amino acids. However, some insects prefer nectar with amino acids and presence of amino acids may increase visitation and capture of insect prey.
紫瓶子草（Sarracenia purpurea L.）是一种食虫植物，其具有吸引昆虫进入充满水的陷阱的额外花蜜。我们鉴定并量化了紫瓶子草叶分泌的额外花蜜中的氨基酸。使用wick-sampling 技术从 32 个瓶子中收集花蜜样本。通过反相高效液相色谱与苯异硫氰酸酯衍生化法分析样本中的氨基酸。在所测试的 32 个花蜜样本中均检测到了可检测量的氨基酸。每个花蜜样本中平均检测到 9 种氨基酸（标准差=2.2）。32 个样本中均未检测到任何氨基酸。每个花蜜样本中的氨基酸含量（即每wick 的含量）平均为 351.4ng（标准差=113.2）。20 个样本中存在 9 种氨基酸（天冬氨酸、半胱氨酸、谷氨酸、甘氨酸、组氨酸、羟脯氨酸、蛋氨酸、丝氨酸、缬氨酸），平均含量为 263.4ng（标准差=94.9），占总氨基酸含量的~75%。由于花蜜中含有氨基酸，因此花蜜的产生可能构成肉食性的巨大成本。然而，一些昆虫更喜欢含有氨基酸的花蜜，并且氨基酸的存在可能会增加昆虫猎物的访问和捕获。
