Department of Botany, Institute of Biosciences, University of São Paulo, São Paulo, SP, Brazil.
Ann Bot. 2024 Nov 13;134(5):711-724. doi: 10.1093/aob/mcae109.
In epiphytic bromeliads, the roots were previously considered to be poorly functional organs in the processes of absorption and metabolization of water and nutrients, while the leaves were considered to always act as protagonists in both functions. More recent discoveries have been changing this old view of the root system.
In this review, we address previous ideas regarding the function performed by the roots of epiphytic bromeliads (mere holdfast structures with low physiological activity) and the importance of a reduced or lack of a root system for the emergence of epiphytism. We present indirect and direct evidence that contradicts this older hypothesis. Furthermore, the importance of the root absorptive function mainly for juvenile tankless epiphytic bromeliads and the characteristics of the root absorption process of adult epiphytic tank bromeliads are discussed thoroughly from a physiological perspective. Finally, some factors (species, substrate, environmental conditions) that influence the absorptive capability of the roots of epiphytic tank bromeliads are also be considered, highlighting the importance that the absorptive role of the roots has for the plasticity of bromeliads that live on trees, which is an environment characterized by intermittent availability of water and nutrients.
The roots of tank-forming epiphytic bromeliads play important roles in the absorption and metabolization of nutrients and water. The importance of roots is greatest for juvenile tankless bromeliads since the root is the main absorptive organ. In larger plants with a tank, although the leaves become the protagonists in the resource acquisition process, the roots complement the absorptive function of the leaf trichomes, resulting in improved growth of these bromeliad. The physiological and biochemical properties of the processes of absorption and distribution of resources in the tissues appear to differ between absorption by trichomes and roots.
在附生凤梨科植物中，根系以前被认为在水分和养分的吸收和代谢过程中功能较差，而叶片则被认为在这两个功能中始终扮演主角。最近的发现改变了对根系的旧有看法。
在这篇综述中，我们探讨了以前关于附生凤梨科植物根系（功能仅仅是固定结构，生理活性低）的功能以及根系减少或缺失对附生现象出现的重要性的观点。我们提出了间接和直接的证据来反驳这一旧假说。此外，从生理学的角度，我们还深入讨论了根系吸收功能主要对幼年期无水槽附生凤梨和成年有水槽附生凤梨根系吸收过程的重要性。最后，还考虑了一些影响附生水槽凤梨根系吸收能力的因素（物种、基质、环境条件），突出了根系吸收作用对生活在树上的凤梨科植物可塑性的重要性，因为树木环境的特点是水分和养分间歇性供应。
水槽形成的附生凤梨科植物的根系在吸收和代谢养分和水分方面发挥着重要作用。对于无水槽幼年期凤梨，根系的重要性最大，因为根系是主要的吸收器官。在有水槽的较大植物中，虽然叶片在资源获取过程中成为主角，但根系补充了叶片毛状体的吸收功能，从而提高了这些凤梨科植物的生长。组织中资源吸收和分配过程的吸收和分布的生理生化特性似乎在毛状体和根系吸收之间存在差异。
