Sandoval-Zapotitla Estela, Terrazas Teresa, Villaseñor José Luís
Jardín Botánico, Instituto de Biología, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Ciudad Universitaria, C.P. 04510, Distrito Federal, México.
Rev Biol Trop. 2010 Jun;58(2):733-55.
Mineral inclusions in plants, of different chemical constitution and forms, have been studied in some plant groups and are currently used as diagnostic tools in taxonomic identifications. With the aim to identify their possible application in taxonomy, mineral inclusions in the leaves of 140 species of Oncidiinae (Orchidaceae) were analyzed and compared. Leave transversal sections were studied with the aid of clear field, phase contrast, and polarized light microscopy. Crystals commonly occured in mesophyll cells, and only in two species those were observed in epidermal cells. Several forms of calcium oxalate crystals and silicdioxide deposits in the form of stegmata were found. The most common crystalline forms were raphides, prisms and druses. Nevertheless, crystals like sands, and concentric and radial plates were also observed in few species. These crystalline forms of concentric and radial plates are reported for the first time in Oncidiinae and Orchidaceae. The stegmata are conical with rough surface, forming tiers along with fibers. Stegmata commonly occur in the vascular bundle sheath and in the abaxial or adaxial fiber bundles. However, few species do not have stegmata in fiber bundles and other species lack both. The taxonomic importance of these mineral inclusions is discussed for the different clades, genera or species within the subtribe Oncidiinae.
植物中具有不同化学组成和形态的矿物质内含物，已在一些植物类群中得到研究，目前被用作分类鉴定的诊断工具。为了确定其在分类学中的可能应用，对140种文心兰亚族（兰科）植物叶片中的矿物质内含物进行了分析和比较。借助明视野、相差和偏光显微镜对叶片横切面进行了研究。晶体常见于叶肉细胞中，仅在两个物种中观察到其存在于表皮细胞中。发现了几种草酸钙晶体形式以及硅质二氧化物以硅质体形式存在。最常见的晶体形式是针晶、棱柱体和晶簇。然而，在少数物种中也观察到了沙状、同心板状和放射状板状晶体。这些同心板状和放射状板状晶体形式在文心兰亚族和兰科中首次被报道。硅质体呈圆锥形，表面粗糙，与纤维一起形成层状。硅质体常见于维管束鞘以及叶背或叶面的纤维束中。然而，少数物种在纤维束中没有硅质体，其他物种则两者都没有。讨论了这些矿物质内含物在文心兰亚族内不同分支、属或物种的分类学重要性。
