Anatomy of the pericarp and seed-coat of Lithraea molleoides (Vell.) Engl. (Anacardiaceae) with taxonomic notes

Abstract

The aim of the present work was to record anatomical data for the fruit and seed of Lithraea molleoides (Vell.) Engl, and compare the results with those for L. brasiliensis and the genera Schinus and Rhus. The L. molleoides fruit was a drupe with a friable and lignified exocarp. The mesocarp was parenchymatous with large secretory canals associated with vascular bundles. The endocarp consisted of four layers: an outer layer of polyhedral cells with prismatic crystals of calcium oxalate, and three inner layers of sclereids in a palisade arrangement. The ovule was anatropous, unitegmic, and crassinucelate. In the chalazal region, a cup-like zone of tanniniferous parenchymal cells formed the hypostase. The developing seed had a circinotropous-like shape, that originated through curvature of the long, coarse funicle that surrounded the tegument and embryo sac. The ripe seed was endotestal with bar-like thickenings or pittings in the cell walls.<br>O fruto de Lithraea molleoides (Vell.) Engl. é uma drupa globosa, branca-acinzentada, lisa, com exocarpo friável e lignificado quando maduro. O mesocarpo é parenquimático com grandes canais secretores associados aos feixes vasculares. O endocarpo é composto de quatro camadas: na camada mais externa as células são poliédricas, com cristais prismáticos de oxalato de cálcio, e nas três camadas internas as células são esclereides em paliçada. O envoltório da semente é membranáceo, liso, amarelo-pálido com uma mancha marrom escura. O óvulo é anátropo, unitegumentado, crassinucelado, inserido em posição basal-lateral. O funículo é crasso e cresce em direção à micrópila formando o obturador funicular. Na região calazal uma zona com células parenquimáticas de conteúdo tanífero formam a hipóstase. A semente em desenvolvimento apresenta uma forma circinótropa, originada a partir da curvatura do funículo crasso e longo que circunda o tegumento e o saco embrionário. A semente madura é endotestal com as paredes das células da endotesta espessadas e lignificadas em forma de barras ou pontuações

Initial development of the endocarp in Lithraea brasiliensis Marchand (Anacardiaceae): with taxonomic notes

“…1D, 2A-E). Because of its development and resulting structure, the endocarp in Lithraea brasiliensis belongs to the Anacardium type, typical in the clade A2 of the Anacardioideae subfamily, which includes Astronium, Cotinus, Euroschinus, Rhodosphaera, Schinus, Schinopsis and Toxicodendron (Wannan 2006), all of which are taxa with Anacardium type endocarp (Wannan and Quinn 1990, CarmelloGuerreiro and Paoli 2002, 2005 and, therefore, very similar to that described in this study.…”

“…2D-E), not being observed during the initial differentiation stages (Figs. 1D, 2A-C), which has also previously been observed in other species (von Teichman and Robbertse 1986, Carmello-Guerreiro and Paoli 2002, 2005.…”

“…Within this context, studies on the origin and development of the mesocarp and endocarp were important for establishing their homologies (von Teichman and Robbertse 1986, von Teichman 1987, von Teichman and van Wyk 1991, Carmello-Guerreiro and Paoli 2002, 2005. Considering the taxonomic importance of the anatomical traits of the pericarp, studies on its development help establish intergeneric relationships and also support the subfamilies Spondioideae and Anacardioideae (Wannan 2006).…”

“…MARIATH Genera such as Rhus, Schinus and Lithraea, among others belonging to the Anacardioideae subfamily, present common pericarp characteristics, such as exocarp sensu lato, parenchymatous mesocarp with secretory cavities or ducts and endocarp sensu stricto with few cell layers, which are usually sclerified (Wannan and Quinn 1990, Wannan 2006, Pell et al 2011. However, there is variability among genera in terms of the number of endocarp layers and occurrence of the crystalliferous layer (Wannan and Quinn 1990, Carmello-Guerreiro and Paoli 2002, 2005, Wannan 2006. Rhus possesses 35 species (Pell et al 2011), although endocarp structural details have only been described for only three of these (von Teichman 1989, Wannan andQuinn 1990).…”

“…Rhus possesses 35 species (Pell et al 2011), although endocarp structural details have only been described for only three of these (von Teichman 1989, Wannan andQuinn 1990). Similarly, Schinus possesses 27 species (Barkley 1957) but endocarp descriptions have been reported for only two (Wannan andQuinn 1990, Carmello-Guerreiro andPaoli 2002), while Lithraea possesses four species (Barkley 1962) and endocarp descriptions have been reported for two of these species, L. brasiliensis and L. molleoides (Pienaar andvon Teichman 1998, Carmello-Guerreiro andPaoli 2005). This reveals that although descriptions of pericarp structure and development are considered to possess 'pronounced diagnostic significance,' there is little knowledge available for a large number of Anacardiaceae species (von Teichman 1989).…”