In this chapter, vegetative morphological characteristics of Teucrium species have been described based on morphological and micromorphological studies. Morphological differentiation of Teucrium sections is also discussed. Most of the Teucrium species are perennial and also a small group of the genus is annual. The members of the genus Teucrium are shrubs, subshrubs, woody at base, rarely whole herbaceous. Several Teucrium species feature stolons or rhizomes and can spread vegetatively. Stem and leaf characters have been put forward in detail according to morphological investigations. The differentiation of leaf morphology is also described. Leaves of Teucrium species are opposite, petiolate, sessile or subsessile, simple, with entire or toothed margin, lobed or pinnatifid. The micromorphological characteristics of the Teucrium species are shown separately. Trichome micromorphology can be used as a discriminating character in the separation of species and subspecies. The trichome types are generally similar on adaxial and abaxial sides of the leaves, but lower sides are mostly denser. Subsessile peltate glandular trichomes are the most seen ones according to the literature and are occurred in almost all the species.