Axillary bud and pericycle involved in the thickening process of the rhizophore nodes in Smilax species

Abstract

The species of the genus Smilax, popularly known as sarsaparilla, are widely used in folk medicine due to the antirheumatic properties of its underground structures. Smilax fluminensis and S. syphilitica occur in forested areas and form thickened stems called rhizophores from which adventitious roots grow. To provide information for more accurate identification of the commercialised product and for elucidating the process of stem thickening, a morphology and anatomy study of the underground organs of the two species was conducted. The adventitious roots differ in colour and diameter depending on the stage of development. They are white and have a larger diameter in the early stages of development, but as they grow, the adventitious roots become brown and have a smaller diameter due to the disintegration of the epidermis and virtually the entire cortex. In brown roots, the covering function is then performed by the lignified endodermis and the remaining walls of the cells from the last parenchyma cortical layer. These results are similar to those found in studies of other Smilax and suggest that the anatomy of the roots can be useful for identifying fraud in commercialised materials. The thickening process of the nodal regions of the rhizophores in both species involves the activity of axillary buds and pericyclic layers.Keywords: sarsaparilla, Smilax, underground system, rhizophore, anatomy.Gema axilar e periciclo envolvidos no processo de espessamento nodal do rizóforo em espécies de Smilax ResumoAs espécies de Smilax, conhecidas popularmente como salsaparrilha, são amplamente utilizadas na medicina tradicional devido às propriedades antirreumáticas das estruturas subterrâneas. Smilax fluminensis e S. syphilitica ocorrem em áreas florestais e formam caules espessados denominados rizóforos a partir dos quais são emitidas raízes adventícias. Com o intuito de fornecer informações para a identificação mais precisa do material comercializado e no entendimento do processo de espessamento do caule, foi realizado o estudo morfológico e anatômico dos órgãos subterrâneos das duas espécies. As raízes adventícias apresentam diferenças na coloração e no diâmetro dependendo da fase de desenvolvimento. As raízes nas fases iniciais do desenvolvimento são brancas e possuem diâmetro maior, porém com o desenvolvimento, devido à desintegração da epiderme e de praticamente todo o córtex, as raízes tornam-se marrons e de diâmetro menor. Nas raízes marrons, a função de revestimento passa a ser exercida pela endoderme lignificada e pelas paredes remanescentes das células da penúltima camada cortical. Os resultados são semelhantes aos encontrados nos estudos de outras Smilax e sugerem que a anatomia das raízes pode ser útil na identificação de fraudes em materiais comercializados. O processo de espessamento das regiões nodais dos rizóforos nas duas espécies envolve a atividade das gemas axilares e de camadas pericíclicas.

Ontogenesis and functions of saxophone stem inAcrocomia aculeata(Arecaceae)

“…Another important role of the hypocotyl is related to the emission of large numbers of adventitious roots that give rise to the fasciculated root system and contribute to the fixation of the seedling and its waterabsorbing capacity. The participation of the hypocotyl in the formation of underground systems has also been seen in structures classified as rhizophores, xilopodia and hypocotyledonary tubers, although most of these studies were undertaken with dicots (Martins et al, 2011;Appezzato-da-Gl oria, 2015;Appezzato-da-Gl oria et al, 2015). The elongation and thickening of the plumule internodes give rise to the tuberous region and contribute to most of the saxophone stem growth.…”