Taxonomic and Adaptive Significance of Hollow Plant Organs

许多种类的植物，在完全不同的谱系中，以有规律地产生中空的茎为特征，具隔节；竹子是经典的例子，马尾草(木贼属)也是如此。在草或竹科的物种中，中空的茎比实心的茎占优势；在古老的马尾科的物种中，现存的所有物种都会产生中空的茎。为了检测中空茎的生物力学特性，康奈尔大学的卡尔·尼克拉斯博士将使用一种被称为多共振频谱(MRFS)的工程技术来研究几种马尾和草。茎的机械刚性或弯曲刚性被认为与光的拦截和繁殖(茎上所生的孢子或种子)有关。争论的焦点是建筑效率(中空杆被认为在新陈代谢上更便宜)和安全性之间的假设权衡(实心杆被认为提供更大的强度)。将分析茎的机械性能，量化和测量来自草和马尾科的一系列物种的刚性方面。在这两个系统上相距较远的植物群中，中空茎构造的共同特征可能很好地提供了趋同进化的例子。

Plants of many species, in quite different lineages, are characterized by the regular production of hollow stems with septate nodes; bamboos are classical examples, as are horsetails (the genus Equisetum). Among species of the grass or bamboo family, hollow stems predominate over solid stems; among species of the ancient horsetail family, all extant species produce hollow stems. In order to examine the biomechanical properties of hollow stems, Dr. Karl Niklas of Cornell University will use an engineering technique known as multiple resonance frequency spectra (MRFS) analysis in the study of several species of horsetails and of grasses. The mechanical rigidity, or flexural rigidity, of stems is thought to be related to light-interception and to reproduction (either spores or seeds borne on that stem). At issue is the hypothesized trade-off between efficiency in construction (hollow stems presumed to be "cheaper" metabolically) and safety from breakage (solid stems presumed to provide greater strength). The mechanical properties of stems will be analyzed, and aspects of rigidity quantified and measured, in an array of species from the grass and horsetail families. Common features of hollow-stem construction in these two phyletically distant groups of plants may well provide examples of convergent evolution.