Shepherd K A, Macfarlane T D, Colmer T D
School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Ann Bot. 2005 May;95(6):917-33. doi: 10.1093/aob/mci101. Epub 2005 Mar 10.
The subfamily Salicornioideae (Chenopodiaceae) are a taxonomically difficult group largely due to the lack of diagnostic characters available to delineate tribal- and generic-level boundaries; a consequence of their reduced floral and vegetative features. This study examined the variation in fruits and seeds across both tribes of the Salicornioideae to assess if characters support traditional taxonomic sections.
Light microscopy, environmental scanning electron microscopy and anatomical ultra-thin sectioning were employed to examine variation in fruits and seeds. Sixty-eight representatives across 14 of the 15 genera currently recognized within the tribes Halopeplideae and Salicornieae were examined to determine whether characters support current taxonomic groups.
Characters such as seed coat structure, embryo shape, seed orientation, the forms of seed storage proteins and carbohydrates show variation within the Salicornioideae and may be phylogenetically useful. The campylotropous ovule typical of the Chenopodiaceae generally results in a curved embryo; however, many Halosarcia and Sclerostegia species have straight embryos and in Salicornia and Sarcocornia the large peripheral embryo appears bent rather than curved. Seed coat ornamentation of Microcnemum and Arthrocnemum is distinct from other Salicornioideae as the elongated epidermal cells of the exotesta have convex walls. Histochemical stains of anatomical sections of cotyledon cells showed protein bodies were variable in shape, and starch grains were present in some species, namely Salicornia bigelovii, S. europaea and Allenrolfea occidentalis.
While fruits and seeds were found to be variable within the subfamily, no synapomorphic characters support the tribe Halopeplideae as these genera have crustaceous seed coats, curved embryos and abundant perisperm; features characteristic of many of the tribe Salicornieae. The endemic Australian genera are closely related and few seed and fruit characters are diagnostic at the generic level. Nineteen characters identified as being potentially informative will be included in future phylogenetic analyses of the subfamily.
盐角草亚科（藜科）在分类学上是一个难以界定的类群，主要原因是缺乏用于划分族和属级界限的鉴别特征；这是其花和营养特征退化的结果。本研究考察了盐角草亚科两个族的果实和种子变异情况，以评估这些特征是否支持传统分类学的组。
采用光学显微镜、环境扫描电子显微镜和解剖超薄切片技术来研究果实和种子的变异。对盐节木族和盐角族目前认可的15个属中的14个属的68个代表物种进行了研究，以确定这些特征是否支持当前的分类类群。
种子表皮结构、胚形状、种子方向、种子贮藏蛋白和碳水化合物的形式等特征在盐角草亚科内存在变异，可能在系统发育上具有参考价值。藜科典型的弯生胚珠通常会形成弯曲的胚；然而，许多盐蓬属和硬枝盐蓬属物种具有直胚，而在盐角属和肉质盐角属中，大的外周胚看起来是弯曲而非弧形。微枝盐角属和节盐木属的种子表皮纹饰与其他盐角草亚科不同，因为外种皮的伸长表皮细胞具有凸起的细胞壁。子叶细胞解剖切片的组织化学染色显示，蛋白体形状各异，一些物种（即比格洛氏盐角草、欧洲盐角草和西方盐节木）的细胞中存在淀粉粒。
虽然发现该亚科内果实和种子存在变异，但没有共衍征支持盐节木族，因为这些属具有硬壳种子表皮、弯曲胚和丰富外胚乳；这些特征是盐角族许多属的典型特征。澳大利亚特有的属亲缘关系密切，在属级水平上很少有种子和果实特征具有鉴别意义。确定的19个可能具有信息价值的特征将纳入该亚科未来的系统发育分析中。
