木槿5个种下类群木材的比较解剖学

Wood comparative anatomy of five intraspecies of Hibiscus syriacus

关键词:  木槿  木材  比较解剖学  物种生物学

Key words:  Hibiscus syriaces  wood  comparative anatomy  biosystematics

摘要:

根据木材结构观察,运用方差分析和数量分类方法,对木槿五个种下类群的种下分类和系统进化进行讨论。结果表明,木槿五个种下类群共同的特征是:半环孔材或环孔材。导管在横切面呈椭圆形,端壁水平或倾斜,单穿孔,导管分布频率相对较少,以复管孔为主,导管分子较短,直径较大。纤维均由大量的韧型纤维和极少量的纤维管胞组成。木射线为异型Ⅱa或异型Ⅱa和Ⅱb,中等射线密度或在紫花单瓣木槿为高密度(每1 mm为12个),单列射线和多列射线均为低射线和细射线。聚类分析和PCD排序结果表明,木槿五个种下类群可分为2个亚种:牡丹木槿和紫花单瓣木槿,前者包括3个变型:雅致木槿、白花重瓣木槿和牡丹木槿,后者包括2个变型:紫花单瓣木槿和紫花重瓣木槿。从木材演化趋势看,紫花单瓣木槿是一个原始类群,该类群在早期分化出牡丹木槿,在晚期分化紫花重瓣木槿,而牡丹木槿又先后分化出雅致木槿和白花重瓣木槿。

Abstract:

On the basis of observations of wood structure,some analytical methods,such as one-way ANOVA and numerical taxonomy,had been applied to solve taxonomic and evolutionary problems in 5 intraspecies of Hibiscus syriacus. The observation showed that 5 intraspecies of Hibiscus syriacus shared wood anatomic characters as follows:the wood was ring or semi ring porous,with obvious growth ring; vessels were ellipse on transverse section,with single perforations in aclinic or oblique end walls,and porous was mostly multiple porous,the frequency of vessels were relatively less. Vessel members were relatively short and wide. Fibres consisted a mass of libriform fibres and a few of tracheid-fibres. Ray was heterogeneous Ⅱa or Ⅱa and Ⅱb type,its frequency was middling or high in Hibiscus syriacus f.syriacus(12 mm^-1). Both of the uniseriate ray and the multiseriate ray were low and thin rays.The result from cluster analysis and principle component analysis(PCA)ordination for wood anatomical characteristics showed that the 5 intraspecies of Hibiscus syriacus should be divided into two subspecies:Hibiscus syriacus subsp.paeoniflorus and H.syriacus subsp.syriacus,and the former might include three forma:H.syriacus f.paeoniflorus,H.syriacus f.albus-plenus and H.syriacus f.elegantissimus,while the latter included two forma:H.syriacus f.syriacus and H.syriacus f.violaceum. According to the evolutionary trend of wood anatomical characteristics,H.syriacus f.syriacus might be the most primitive taxon,from which H.syriacus f.paeoniflorus and H.syriacus f.syriacus originated,respectively in earlier and later development stage,and from H.syriacus f.paeoniflorus, H.syriacus f.elegantissimus and H.syriacus f.albus-plenus successively differentiated.