Leaf architecture and anatomy of eight species of Tilia (Malvaceae)
2024
Marysol Ramírez-Díaz | Jorge Gutiérrez | Teresa Terrazas
Background and Aims: The genus Tilia (Malvaceae) consists of approximately 23 species with unclear boundaries between some of them, especially for the species and subspecies of North America. Although their leaf variation has been recorded, it has not been studied comparatively with other Tilia species present in Europe or Asia. The purpose of this work was to identify leaf morpho-anatomical characters that contribute to Tilia species differentiation. In this work we describe and compare the leaf architecture and anatomy of eight species and four subspecies belonging to the genus Tilia. Methods: Leaves of eight species and four subspecies were collected or removed from collections. Complete leaves were cleared and stained to describe their architecture, and their anatomy was characterized through transverse and paradermal sections. Key results: Results showed that leaves are variable in shape, margin dentate with first and second order teeth, secondary venation mostly craspedodromous and well-developed areole. Leaves were hypostomatic heterobaric and with three types of midvein. The combination of characters favored the recognition of species. For example, T. platyphyllos is characterized by teeth with narrower bases, T. mongolica is the only species with a deltoid lamina and without domatia, and T. caroliniana subsp. occidentalis is distinguished by the lamina with three teeth per cm and four-armed stellate trichomes with a length of 332 µm. A key is provided for species and subspecies studied. Conclusions: The different combinations of leaf characters are promising for the systematics of the genus Tilia.
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