Am J Bot. 1998 May;85(5):736.
Nectaries on fronds of Polypodium spp. have been studied previously only in cultivated specimens. We conducted field observations in middle-elevation forests in Mexico and found five ant species associated with nectaries of Polypodium plebeium and P. lepidotrichum. To investigate whether nectaries promote protection against herbivores, we performed ant-exclusion experiments with nectary-bearing ferns (P. plebeium) and other ferns without nectaries (Polypodium plesiosorum, P. furfuraceum, and Phlebodium pseudoaureum). When ants were excluded from the developing fronds of Polypodium plebeium, damage from foliage-feeding sawfly and lepidopteran caterpillars was significantly greater than in control fronds. Ferns without nectaries did not show a difference in damage between ant-excluded and control fronds. Our results demonstrate that fern nectaries can support ant defense of the plant body as do the extrafloral nectaries of many angiosperms.
此前，仅对栽培标本中的 Polypodium 属植物叶片上的蜜腺进行过研究。我们在墨西哥中海拔森林中进行了实地观察，发现有 5 种蚂蚁与 Polypodium plebeium 和 P. lepidotrichum 的蜜腺有关。为了研究蜜腺是否有助于抵御食草动物，我们对具有蜜腺的蕨类植物（P. plebeium）和其他没有蜜腺的蕨类植物（Polypodium plesiosorum、P. furfuraceum 和 Phlebodium pseudoaureum）进行了蚂蚁排除实验。当蚂蚁被排除在 Polypodium plebeium 的发育叶片之外时，食叶性叶蜂和鳞翅目毛毛虫造成的损害明显大于对照叶片。没有蜜腺的蕨类植物在被蚂蚁排除和对照叶片之间没有表现出损害差异。我们的结果表明，蕨类植物的蜜腺可以像许多被子植物的额外蜜腺一样，为蚂蚁保护植物提供支持。
