Structural characterization of vegetative organs of the endangered Brazilian native species Hesperozygis ringens (Benth.) Epling

Abstract The aim of this study was to describe the structural characterization of Hesperozygis ringens (Benth.) Epling vegetative organs. For this purpose, leaves, stems and roots of the endangered Lamiaceae were collected from a population located in Santo Antão, Santa Maria municipality, Rio Grande do Sul, Brazil. Results demonstrated that the H. ringens leaf blade presents glandular and non-glandular trichomes as well as two morphs of diallelocytic stomata, which are usually found above the epidermis level. The petiole is concave on ventral face and convex on its dorsal face, containing glandular and non-glandular trichomes as well as stomata in the epidermis. These types of trichomes were also detected in the stem. In addition, the presence of intercellular spaces within the organ is highlighted. Stomata above epidermis level also occurred in the stem. Phenolic idioblasts were found in the cortical region of plant root and deposit of lipophilic substance was observed in phloem cells. Great amount of apparently two different crystals were detected in all organs. Information obtained in this study provides knowledge about the characterizationof H. ringens, which may be used to distinguish characters of taxa and can help understand the species survival in its occurrence sites.

摘要 本研究旨在阐明齿叶蜡花（Hesperozygis ringens (Benth.) Epling）营养器官（vegetative organs）的结构特征。研究人员采集了隶属于唇形科（Lamiaceae）的濒危物种的叶、茎与根，其种群分布于巴西南里奥格兰德州圣玛丽亚市圣安东昂区域。结果表明，H. ringens的叶片表皮存在腺毛（glandular trichomes）与非腺毛（non-glandular trichomes），以及两种形态的双列细胞型气孔（diallelocytic stomata），此类气孔通常突出于表皮层面之上。叶柄腹面凹陷、背面隆起，表皮中分布有腺毛、非腺毛与气孔；茎部同样检出上述两类毛状体。此外，该器官内存在细胞间隙（intercellular spaces），茎部亦存在突出于表皮的气孔。在植物根的皮层区域（cortical region）中发现含酚异细胞（phenolic idioblasts），韧皮部细胞（phloem cells）内观察到亲脂性物质沉积。所有器官中均检测到两种显著不同的晶体。本研究获取的信息可为H. ringens的特征鉴定提供依据，可用于区分不同类群的性状特征，亦有助于理解该物种在其原生分布地的生存机制。