Seed morphology of the European species ofEricaL. sect.ArsaceSalisb. ex Benth. (Ericaceae)

Abstract

Abstract.-The seed morphology of Erica arborea and E. lusitanica, the two European species of section Arsace, was studied. The results reflect very significant differences between the two species, mainly in size and shape of the seeds, testa sculpture and surface cells boundaries. The seeds of E. arborea are larger, with a striated pattern and anastomosed cells, while E. lusitanica has seeds below 0.4 mm, rounder and with a reticulate surface pattern and channelled cell boundaries. The seeds of E. arborea are grouped in two main seed types that correspond to the Macaronesian and the Iberian peninsular populations. Some African, Central and Eastern Mediterranean populations have intermediate values, but closer to the non Macaronesian populations. Seed morphology is also a taxonomic character for the two subspecies of E. lusitanica, with larger, more elongated seeds in subsp. cantabrica than in subsp. lusitanica. These results suggest a higher taxonomic distance between E. arborea and E. lusitanica than what has been considered in classical studies.Key words : Erica arborea -Erica lusitanica -taxonomy -SEM pictures -testa sculpture.Résumé.-On étudie la morphologie des graines d'Erica arborea et d'E. lusitanica, les deux espèces européennes de la section Arsace. Les résultats montrent des différences très significatives entre elles, surtout dans la taille et la forme des graines, la structure de la testa et les espaces intercellulaires. Les graines d'E. arborea sont plus grandes, avec un dessin à raies et des cellules fusionnées, alors qu'E. lusitanica a des graines de 0.4 millimètre, plus arrondies et avec la surface réticulé et les limites des cellules canalisées. Les graines d'E. arborea sont groupées en deux types principaux, celles qui correspondent á la Macaronésie et les populations de la Péninsule Ibérique. Certaines populations africaines et du Centre et de l`Est méditerranéens ont des valeurs intermé-diaires, mais plus proches des populations non macaronésiennes. La morphologie des graines est aussi un caractère taxonomique pour les deux sous-espèces d'E. lusitanica, avec les graines plus grandes dans la subsp. cantabrica et plus petites et arrondies dans la subsp. lusitanica. Ces résultats suggèrent une plus grande distance taxonomique entre E. arborea et E. lusitanica que ce qui a été considéré dans les études classiques.Mots clés : Erica arborea -Erica lusitanica -taxonomie -images MEB -ornementation de la testa.

Description and systematic affinity of flower and seed fossils of Erica sect. Chlorocodon (Ericaceae) from the early Pleistocene of Madeira Island, Portugal

“…The morphology of seeds of extant European and Macaronesian Erica species was studied in the last decades, revealing their taxonomical value (Huckerby & al., 1972; Fagúndez & Izco, 2003, 2009, 2010, 2011; Szkudlarz, 2009; Fagúndez & al., 2010). The Madeiran seed fossils fit within the WPBH seed size and morphology and undoubtedly differ from other species currently growing in Madeira (i.e., E. arborea s.l.…”

“…(= E. arborea + E. canariensis ) and E. maderensis are larger (major axis in both ca. 0.6–0.7 mm), present a distinct testa ornamentation (striated and reticulate, respectively), cell shape (elongated, and isodiametric or slightly elongated, respectively) and cell boundaries (anastomosing, and channelled or anastomosing, respectively) (Fagúndez & Izco, 2009, 2010). Comparing to the insular E .…”

“…Flower identification was achieved by comparing it to herbarium material (Appendix 1) and to the literature (McClintock, 1989, 1994; Nelson, 2009, 2011). SEM images of seed fossils were compared with extant SEM images of Macaronesian and mainland seeds (Fagúndez & Izco, 2003, 2009, 2010; Szkudlarz, 2009). Flower description follows the nomenclature given by Menezes de Sequeira (1997), while seed description follows Szkudlarz (2009) and Fagúndez & Izco (2003).…”