Morozowska Maria, Woźnicka Agata, Nowińska Renata
Department of Botany, Faculty of Agronomy, Horticulture and Bioengineering, Poznań University of Life Sciences, Poznań, Poland.
Legnica, Poland.
PeerJ. 2021 Oct 28;9:e12170. doi: 10.7717/peerj.12170. eCollection 2021.
The genus is known for its complicated taxonomy and extreme polymorphism. Currently, dogwoods are classified into four morphological groups reflected in four phylogenetic clades: blue- or white-fruited dogwoods (BW), cornelian cherries (CC), big-bracted dogwoods (BB), and dwarf dogwoods (DW). The present study is a continuation of a series of papers that started with the examination of the endocarp morphological diversity among BW species. The endocarps of 22 species were studied according to their morphology, internal structure, and sculpture; the aim was to evaluate the taxonomic importance of the examined characters and check whether endocarp differentiation supports the published phylogenies, according to which the relationships within the genus are indicated as (BW(CC(DW-BB))). Among the quantitative characters, the endocarp's length, thickness, and width, its length/width ratio, and the number of vascular bundles on its surface were considered taxonomically important. Regarding the qualitative characters, the taxonomic significance of the stone shape, the endocarp apex and base outline, the position of vascular bundles on the endocarp surface, and the presence of the apical cavity and distinct furrow on the endocarp side walls was proved. Additionally, the uniform qualitative characters having a 100% share of a given character state were identified. Cornelian cherries and dwarf dogwoods were characterised by the presence of four uniform characters. In the big-bracted group, two uniform characters were found. Blue- or white-fruited species were the most heterogeneous, with no uniform characters. Regarding the endocarp's internal structure, the presence of secretory cavities in the endocarp wall and in the septa, the presence of crystals in the outer endocarp, the number of cell layers in the transition sclereid zone, and the primary and secondary sculptures were found to be taxonomically significant. Additionally, the comparative analyses of dogwood endocarps found the following parameters to be useful: the germination valve thickness, the ratio of endocarp wall thickness to endocarp diameter, and the septum's width and structure. Due to the great differentiation of the examined characters, it was difficult to verify the research hypothesis unambiguously. The calculated similarity coefficients of the endocarps' qualitative and quantitative characters revealed the highest morphological similarity of endocarps between DW and BB groups, supporting the phylogenetic relationships based on molecular evidence. The number of vascular bundles on the endocarp surface was the character that supported this similarity the most. The similarity coefficients calculated separately for qualitative characters showed the closest similarity between groups CC-DW. However, these results do not directly reflect any of the published phylogenies.
该属以其复杂的分类学和极端的多态性而闻名。目前，山茱萸被分为四个形态学组，这四个组在四个系统发育分支中得到体现：蓝果或白果山茱萸（BW）、欧亚山茱萸（CC）、大苞片山茱萸（BB）和矮山茱萸（DW）。本研究是一系列论文的延续，这些论文始于对BW组物种内果皮形态多样性的研究。对22种山茱萸的内果皮进行了形态、内部结构和纹饰方面的研究；目的是评估所研究特征的分类学重要性，并检验内果皮分化是否支持已发表的系统发育树，根据该系统发育树，该属内的关系表示为（BW(CC(DW - BB))）。在定量特征中，内果皮的长度、厚度和宽度、其长宽比以及表面维管束的数量被认为具有分类学重要性。关于定性特征，证明了果核形状、内果皮顶端和基部轮廓、维管束在内果皮表面的位置以及内果皮侧壁上顶端腔和明显沟槽的存在具有分类学意义。此外，还确定了具有100%给定特征状态份额的统一定性特征。欧亚山茱萸和矮山茱萸的特征是存在四个统一特征。在大苞片组中，发现了两个统一特征。蓝果或白果物种是最具异质性的，没有统一特征。关于内果皮的内部结构，发现内果皮壁和隔膜中分泌腔的存在、外果皮中晶体的存在、过渡石细胞区的细胞层数以及初生和次生纹饰具有分类学意义。此外，对山茱萸内果皮的比较分析发现以下参数是有用的：萌发孔厚度、内果皮壁厚度与内果皮直径的比值以及隔膜的宽度和结构。由于所研究特征的巨大差异，很难明确验证研究假设。计算得到的内果皮定性和定量特征的相似系数显示，DW组和BB组内果皮的形态相似性最高，这支持了基于分子证据的系统发育关系。内果皮表面维管束的数量是最能支持这种相似性的特征。分别为定性特征计算的相似系数显示CC - DW组之间的相似性最接近。然而，这些结果并没有直接反映任何已发表的系统发育树。
