The value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean members of the genusPinus

Abstract

This study reports the value of leaf cuticle characteristics in the identification and classification of Iberian Mediterranean species of the genus Pinus (P. nigra subsp. salzmannii, P. pinaster, P. pinea and P. halepensis), with the aim of using these characters to identify isolated cuticles and stomata in palynology slides. Preparations were made of the cuticles of pine needles belonging to one natural Iberian population of each of the above species. A number of epidermal morphological characteristics were then recorded with the aim of distinguishing these species from one another. The structure of the stomatal complex (the shape and arrangement of the subsidiary cells) was different in each species. The aperture of the epistomatal chamber was significantly smaller in P. pinea than in the other species examined, and the variables recorded for the thickening of the guard cells provided relationships that clearly distinguished all four taxa. The width and length of the stomata and the upper woody lamellae, the central distance between the external limits of the medial lamellae borders and the length of the stem were the most useful variables in this respect. The present results contribute to the ongoing discussion regarding the taxonomic classification of the members of Pinus, and provide valuable clues for the identification of Iberian Mediterranean pine species from small pine needle fragments or isolated stomata. After validation of the present results for multiple populations, these results could also be used to help identify fossil leaf macroremains and the scattered/ isolated stomata commonly observed in palaeopalynological samples.

A taxonomic tool for identifying needle remains of south-western EuropeanPinusspecies of the Late Quaternary

“…This work provides a means of identifying pine needle fragments at the species level for the six Pinus spp. in south‐western Europe and confirms the results of previous studies that dealt with more limited material (García Álvarez et al ., , b). Qualitative epidermal features (shape, relative size and arrangement of the cells of the stomatal rows) allow P. halepensis , P. pinea , P. pinaster , P. sylvestris and the group P. gr.…”

“…Sixteen variables (Fig. ) reported in earlier studies (Trautmann, ; Hansen, ; Sweeney, ; García Álvarez et al ., , b) were measured for ten stomata per needle, following the same procedure described for variable p .…”

“…Stružková () and García Álvarez et al . (2009a, b) were among the first to provide an identification tool for European Pinus spp. based on needle epidermal features.…”

“…All these taxa belong to Pinus subgenus Pinus and have two needles per dwarf‐shoot that are striped with rows of stomata on the adaxial and abaxial surfaces (Mirov, ; Farjon, ; Ruiz de la Torre, ). Taxonomic studies based on needle epidermis features suggest that some of these species can be identified by Florin ring characteristics, the thickness of the epidermal cells or the shape and arrangement of the subsidiary cells of the stomatal complex (Yoshie & Sakai, ; Boratyńska & Bobowicz, ; Stružková, ; Boratyńska & Boratyński, ; García Álvarez et al ., , b). However, these investigations analysed different taxa separately or in small groups (Stružková, ), a single population per species (Yoshie & Sakai, ; García Álvarez et al ., , b) or cross‐section features that could be poorly preserved in fossil material (Boratyńska & Bobowicz, ).…”

Late Pleistocene–Holocene palaeoenvironmental evolution of the Añamaza River valley (Iberian Range, NE Spain): Multidisciplinary approach on the study of carbonate fluvial systems

“…Differentiation of three pollen types within Quercus pollen is based on specific morphological keys from Planchais (1962), Colombo et al (1983) and van Benthem et al (1984). Pinus stomata types were identified using identification keys of Trautmann (1953), Hansen (1995), Sweeney (2004) and García Álvarez et al (2009aGarcía Álvarez et al ( , 2009b.…”