Anatomy, palynology and nutlet micromorphology of Turkish endemic Teucrium sandrasicum (Lamiaceae)

Abstract

In this study, the anatomical features of the leaf and stem, besides the pollen and nutlet characteristics of Teucrium sandrasicum are investigated. T. sandrasicum, belonging to sect. Teucrium, is an endemic perennial herb growing on serpentine around Mugla province. The anatomical studies on T. sandrasicum revealed that the stem shares the general characteristics of the Labiatae family. The leaves clearly exhibit xeromorphy due to features such as the distribution of stomata on the lower surface (hipostomatic), the occurrence of guard cells below the epidermis (xeromorphic type), inrolled margins, thick cuticle layer, thick outer epidermal cell wall, a high density of trichomes and thick palisade layer of the mesophyll. The anatomical studies showed that the upper epidermal cells of the leaf include many spherocrystals. The pollen grains are prolate, medium in size, 3-colpate with verrucate ornamentation. The nutlets are ellipsoid with a reticulate-verrucate surface. The results have proven thatT. sandrasicum is different from the other species of the sect. Teucrium because of the branched trichomes on the stem and the lack of eglandular trichomes on the nutlets.

Stem and leaf anatomy of three taxa in Lamiaceae

“…In cross-section, the stem is quadrangular, collenchyma tissue covers a large area at the corner and one-two layers betweeen the corners. These features are previously reported in some other investigated members by several authors (Metcalfe and Chalk 1972, Bosabalitis and Kokkini 1997, Gönüz and Özörgücü 1999, Dinç et al 2008. On the other hand, the cortex size and collenchyma thickenes in the corners, trachea size and pith cell size O. vulgare ssp.…”

“…It is reported that high density of trichomes and thick palisade tissue of mesophyll could be interpreted as xerophytic characters. These features were reported in T. sandrasicum (Dinç et al 2008), T. montanum and T. polium (Dinç et al 2011). The upper epidermal cells are distinctly larger than the lower ones in T. hircanum, while it is almost equal to the lower one in O. rotundifolium.…”

Anatomical and nutlet differentiation between Teucrium montanum and T. polium from Turkey

“…Metcalfe & Chalk (1950) pointed out that the stems of the family Lamiaceae species are rectangular and the collenchymatic tissue covers broad area at the corners, and a developed scleranchymatic tissue surrounds the vascular tissue. The anatomical studies on some of the genus Teucrium species showed that they had the same anatomical characteristics as well (Dinç et al 2008a(Dinç et al ,b, 2009. In contradistinction to previously…”

“…The more restricted occurrence of the spherocrystals enhances its diagnostic value (Metcalfe & Chalk 1983). Spherocrystals are present in leaf epidermal cells of some species from section Teucrium and section Scordium (Dinç et al 2008a(Dinç et al ,b, 2009). The presently studied species from section Polium lack spherocrystals.…”

“…and T. orientale L. var. orientale from section Teucrium (Dinç et al 2008a(Dinç et al ,b, 2009. The leaves are hypostomatic in the both species from section Polium (Mill.)…”