Seed morphology and anatomy of the Mediterranean pentamerous species of Erica (Ericaceae)

Authors: JAIME FAGUNDEZ, JESUS IZCO

Abstract: The species of the "Pentapera group" are distinguished from the rest of the European and Mediterranean Erica L. species by having 5 corolla lobes and sepals instead of 4, and 10 stamens instead of 8. The genus Pentapera Klotzsch was proposed for these taxa but recent studies regards it as part of Erica. Two species are recognised: Erica sicula Guss. and E. bocquetii (Peşmen) P.F.Stevens, and 3 subspecies have been described within E. sicula. This taxonomic treatment is still under discussion and relationships with other species have been poorly discussed. Seed morphology of the 2 species and the 3 subspecies was studied by means of scanning electron microscope techniques. Characters concerning size and shape of seeds, and primary and secondary ornamentation were observed and measured. Anatomy of the seed coat was analysed in 2 populations of E. sicula subsp. libanotica (C.Barbey) P.F.Stevens using a light microscope, and seed coat thickness and cell junctions were measured. Seeds range from 0.45 to 0.8 mm; shape is ellipsoid, oblong, or obovoid with a lateral wing; primary ornamentation is striate while secondary ornamentation shows smooth outer anticlinal walls and indented or smooth outer periclinal walls. Clear differences were found for the studied taxa. The seeds of E. bocquetii have the lowest values for size and lack an indented surface; this is shared with E. sicula subsp. libanotica. E. sicula subsp. sicula has an indented surface and E. sicula subsp. cyrenaica Brullo & Furnari has smaller, rounder seeds. Compared to the rest of the northern Erica species, seed coat sections reveal similarities with E. arborea L. and E. australis L, and seed morphology relate this group with E. ciliaris L. but most of all with E. arborea

Keywords: Erica, Pentapera, Ericaceae, seed morphology, seed anatomy, taxonomy, SEM

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