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The effect of various pretreatments, culture conditions, and storage time on in vitro germination of seeds, as well as the effect of explant origin and plant growth regulators on in vitro propagation of Teucrium capitatum L. (Teucrium polium sp. capitatum Arcang., Lamiaceae) were examined. Seeds, collected from native plants and stored at room temperature for 3, 7, and 12 months, were cultured for germination in vitro in petri dishes with solid half-strength (½) Murashige and Skoog (1962) growth medium (MS) at 5, 10, 15, 20, 25, and 30 °C, and 16 hours light or continuous darkness. Pretreatments, such as cold stratification, scarification with sandpaper, dipping in concentrated sulfuric acid (H₂SO₄ > 95%), or dipping in boiling water were tested. Seeds without any pretreatment germinated at lower than 10%. Dipping in concentrated H₂SO₄ for 15 or 20 minutes was the most effective pretreatment, but still seed germination achieved was low (36%). Seeds preserved their germination capacity for at least 1 year, and germinated satisfactorily at a wide temperature range, from 15 to 25 °C (optimum), while photoperiod did not affect seed germination. Explants excised from in vitro-grown seedlings were established in vitro on MS medium with 1.0 mg·L⁻¹ 6-benzyladenine (BA) at much higher rates (≈90%) compared with those collected from plants grown from cuttings in a greenhouse (25%), while explants collected from adult wild plants failed to do so. Explants from seedlings showed strong variability in their response; those excised from branched seedlings formed shoots at significantly higher percentage (90%) at the establishment stage (cultured on MS medium with 0.5–2.0 mg·L⁻¹ BA) than explants excised from unbranched seedlings (36% to 43%), while during subcultures on MS medium with 1.0 mg·L⁻¹ BA, explants from branched seedlings also showed higher multiplication rates than those from unbranched ones. BA at 0.5–2.0 mg·L⁻¹ induced shoot multiplication during both establishment and multiplication stages (7–8 and 14–15 shoots per explant, respectively), while kinetin and 6-γ-γ-(dimethylallylamino)-purine (2iP) were less effective than BA, and zeatin the least appropriate. Microshoot rooting was enhanced by 1-week culture on (½) MS medium with 1.0–4.0 mg·L⁻¹ indole-3-butyric acid (IBA), followed by transfer to auxin-free, (½) MS medium (93% to 98%, 7–8 roots per microshoot), compared with culture on the same medium continuously for 5 weeks (69% to 80%, 5–6 roots per microshoot) or at lower IBA concentrations. Plantlets were acclimatized to ex vitro conditions at 98% on a peat–perlite (1:1, v/v) mixture.

The aim of this study was to develop an efficient protocol for in vitro propagation of the rare and endangered ×Malosorbus florentina, not only enabling conservation of the species, but also its use as an ornamental. Explants excised from adult plants, shoot tip explants, and explants collected in March and April showed more browning and had higher content of total phenolics than explants excised from juvenile tissue, nodal explants, and those collected during any of the other months of the year. Shoot tip explants from adult plants were more difficult to establish in vitro (14%) compared with explants from micropropagated plantlets or sprouts of burned plants (29% to 36%). Nodal explants excised from seedlings were established at the highest percentage (83%), giving the most shoots per explant (5.2). Generally, in vitro cultures established from adult plants, with the exception of one culture, showed lower multiplication rates compared with cultures from juvenile plants. Nodal explants from the base of sprouts produced a higher percentage (60%) of shoots than explants from upper locations (20% to 31%), but any differences in proliferation rates of established cultures ceased after the third subculture. Microshoots from juvenile cultures were more capable of rooting (51% to 58%) than were those from adult plants (16% to 32%), whereas 83% of the plantlets were acclimatized ex vitro independently of their origin, but plantlets of juvenile origin, although developing the same height as those originating from adult plants, had shorter internodes and thus more compact shape.