Machado S R, Morellato L P C, Sajo M G, Oliveira P S
Departamento de Botânica, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, Brazil.
Plant Biol (Stuttg). 2008 Sep;10(5):660-73. doi: 10.1111/j.1438-8677.2008.00068.x.
Extrafloral nectaries are nectar-secreting structures that are especially common among the woody flora of the Brazilian cerrado, a savanna-like vegetation. In this study, we provide morphological and anatomical descriptions of extrafloral nectaries (EFNs) occurring on vegetative and reproductive organs of several plant species from the cerrado, and discuss their function and ecological relevance. We describe the morphology and anatomy of EFNs of 40 species belonging to 15 woody families using scanning electron microscopy and light microscopy. We categorise EFNs following a structural-topographical classification, and characterise the vascularised and complex nectaries, amorphous nectaries and secretory trichomes. Fabaceae, Bignoniaceae, Malpighiaceae and Vochysiaceae were the plant families with the majority of species having EFNs. Ten species possess more than one morphotype of gland structure. Observations and experimental field studies in the cerrado support the anti-herbivore role of EFN-gathering ants in this habitat. Additional morphological studies of EFNs-bearing plants, including other growth forms (e.g. herbs and lianas), are being undertaken and will hopefully cast further light on the ecological relevance of these glands in the cerrado, especially with respect to their attractiveness to multiple visitors.
花外蜜腺是分泌花蜜的结构，在巴西塞拉多的木本植物群中尤为常见，塞拉多是一种类似稀树草原的植被。在本研究中，我们对塞拉多几种植物营养器官和生殖器官上的花外蜜腺进行了形态学和解剖学描述，并讨论了它们的功能和生态相关性。我们使用扫描电子显微镜和光学显微镜描述了15个木本科40种植物花外蜜腺的形态和解剖结构。我们根据结构-地形分类对花外蜜腺进行分类，并对维管束化的复杂蜜腺、无定形蜜腺和分泌毛状体进行了特征描述。豆科、紫葳科、金虎尾科和萼囊花科是拥有花外蜜腺物种最多的植物科。有10个物种拥有不止一种腺体结构形态型。在塞拉多进行的观察和实地实验研究支持了采集花外蜜腺的蚂蚁在该栖息地中具有的抗食草动物作用。目前正在对具有花外蜜腺的植物进行更多的形态学研究，包括其他生长形式（如草本植物和藤本植物），有望进一步阐明这些腺体在塞拉多的生态相关性，特别是它们对多种访客的吸引力。
