Departamento de Botânica, Universidade de São Paulo, Instituto de Biociências, Rua do Matão, 277, São Paulo-SP, 05508-090, Brazil.
Universidade Federal do ABC, Centro de Ciências Naturais e Humanas (CCNH), Rua Arcturus, 03, São Bernardo do Campo-SP, 09606-070, Brazil.
Am J Bot. 2020 Dec;107(12):1622-1634. doi: 10.1002/ajb2.1577. Epub 2020 Dec 3.
Lianas are intriguing forest components in the tropics worldwide. They are characterized by thin and flexible stems, which have been related to a unique stem anatomy. Here, we hypothesized that the anatomical diversity of lianas, varying in shapes, proportions, and dimensions of tissues and cell types, would result in different stem bending stiffnesses across species. To test this hypothesis, we chose four abundant liana species of central Amazonia belonging to the monophyletic tribe Bignonieae (Bignoniaceae) and compared their basal stems for their anatomical architectures and bending properties.
Measurements of anatomical architecture and bending stiffness (structural Young's modulus) included light microscopy observations and three-point bending tests, which were performed on basal stems of eight individuals from four Bignonieae species. All analyses, including comparisons among species and relationships between stem stiffness and anatomical architecture, were performed using linear models.
Although the anatomical architecture of each species consists of different qualitative and quantitative combinations of both tissues and cell types in basal stems, all species analyzed showed similarly lower bending stiffnesses. This similarity was shown to be directly related to high bark contribution to the second moment of area, vessel area and ray width.
Similar values of stem bending stiffness were encountered in four liana species analyzed despite their variable anatomical architectures. This pattern provides new evidence of how different quantitative combinations of tissue and cell types in the basal stems of lianas can generate similarly low levels of stiffness in a group of closely related species.
藤本植物是全球热带森林中引人入胜的组成部分。它们的特点是茎干细而柔韧，这与独特的茎解剖结构有关。在这里，我们假设藤本植物的解剖结构多样性，表现在形状、组织和细胞类型的比例和尺寸上，会导致不同物种的茎弯曲刚度不同。为了验证这一假设，我们选择了中亚马逊地区的四个丰富的藤本植物物种，它们属于单系的大血藤族（紫葳科），并比较了它们的基部茎干的解剖结构和弯曲特性。
解剖结构和弯曲刚度（结构杨氏模量）的测量包括对四个大血藤族物种的 8 个个体的基部茎干进行光镜观察和三点弯曲试验。所有的分析，包括种间比较和茎刚度与解剖结构的关系，都是用线性模型进行的。
尽管每个物种的解剖结构在基部茎干中都由不同的定性和定量的组织和细胞类型组合而成，但所有分析的物种都表现出相似的较低弯曲刚度。这种相似性被证明与高树皮对第二矩、导管面积和射线宽度的贡献直接相关。
尽管分析的四个藤本植物物种的解剖结构不同，但它们的茎弯曲刚度值相似。这一模式为不同定量组合的组织和细胞类型在藤本植物基部茎干中如何产生相似的低刚度水平提供了新的证据，这在一组密切相关的物种中是如此。
