The diagnosticity assessment of the morphological characteristics among taxa of Teucrium sect. Polium growing in Iran

Twelve species of the genus Teucrium L. growing in Iran have been positioned within 6 sections. Known by 5 taxa, the most taxonomically controversial group is the sect. Polium Screb. T. stocksianum Boiss. by having 4 varieties together with T. polium L. constitute the sect. Polium in Iran. Characteristics of the inflorescences, corolla, calyx, leaves and indumentum provide the most applicable evidence for classifying taxa of the genus. The examined plant materials were provided through extensive botanical field studies. Where available representatives of at least 3 populations of each taxon were investigated. T. polium was studied by 10 different geographical populations. In accordance with the related literature 32 quantitative or qualitative (vegetative/floral) traits were selected and measured. Several substantial traits including branched trichomes, linearspatulate bracts, tubular-obconical calyx with obtuse teeth, whitish corolla and branched inflorescence could evidently set T. polium apart from T. stocksianum. The var. stocksianum is thoroughly covered by a dense indumentum of adpressed, crisped and vermiform hairs. By having the same indumentum type, the var. gabrielae (Bornm.) Jamzad is well specified by entire, flat-margined and lanceolate leaves. Bracts and calyces of var. incanum (Aitch. & Hemsl.) Hedge & Lamond wear a unique hair coverage consisted of long, erect-curved simple and capitate glandular hairs. Bracts are sometimes ciliated. Stems of the var. patulum Hedge & Lamond is densely coated with semierect, rough hairs especially on the upper parts. Bracts more or less sparsely and calyx almost densely are covered by short semierect hairs along with capitate glands. The bracts are also occasionally ciliated. Overall, different aspects of the trichome coverage provided the most diagnostic characteristics useful at both specific and infraspecific ranks within the section. Secondly, the shape of bracts is handy for identifying half of the studied taxa. Afterwards, general perspective, corolla color and properties of leaves, calyx and inflorescence remain still as useful taxonomic tools. In the case of quantitative properties, in total there is no reliable and steady trait at list within T. stocksianum complex. However, quantitative characteristics can still be counted on as subsidiary data along with qualitative ones. It is worth to note the corolla color appear somewhat as a continuous characteristic within T. stocksianum complex and such an unreliable property is not to be considered as a diagnostic property

کلیدواژه ها:

Taxonomy ، morphological characteristics ، Teucrium ، Lamiaceae