Carpology of the species of <i>Ferula</i> subgen. <i>Merwia</i> (Umbelliferae–Apioideae) and some taxonomic implications

The genus Ferula L., with 180–185 species, is one of the largest genera of the Umbelliferae (Apiaceae). It is distributed in the ancient Mediterranean florogenetic area extending from Macaronesia, northeast Africa and the Iberian Peninsula to middle Asia, China and western Himalaya. One hundred and seventy‐five species occur in Asia; the biodiversity centers being in central Asia, Iran and Afghanistan. The presently adopted classification of Ferula by E. P. Korovin is based on leaf, synflorescence, flower and fruit morphology, as well as some ecological considerations. Among fruit anatomical characters only the number of vittae (secretory ducts) was used to divide Ferula into six subgenera, one of which is Merwia . Fruit anatomy and morphology will be useful for a taxonomic revision of Ferula . In the present study, free‐hand and microtome sections of mericarps were studied with light microscopy, and fruit surfaces with SEM. Twenty‐two species, attributed to the subgenus Merwia as well as Ferula ghorana , were studied for the first time. The species differ from one another in the presence/absence of an indumentum, hair morphology and surface structure, position and number of vittae and vascular bundles, degree of development of marginal ribs, the presence or absence in the mesocarp of an outer collenchymatous layer and an inner mechanical layer. The studied species were divided into six carpological groups. The results suggest that the subgenus is not a natural monophyletic taxon. It is suggested that the name Merwia should be reserved for a small section which includes Ferula litwinowiana and the closest desert species, while other species of Merwia may be classified in several oligotypic sections. Ferula decurrens and F. mogoltavica have erroneously been regarded as having an affinity with F. litwinowiana .

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