Fig. 5

The successive developmental stages of Orchis militaris seed germination in asymbiotic culture in vitro for 16 months. A Stage 1: immature seeds with intact testa. B Stage 2: imbibed seed (IS) and seeds with swollen embryo in the width of seed coat, splitting of testa followed by protocorm emergence (PE)—Stage 3. C Stage 3: rhizoids (R) are formed on protocorm. D Stage 4: protocorm enlargement with apical meristem (AM) sinking. E Stage 4: superficial disc grows into a conical meristematic dome. F Stage 4: protocorm possesses 2 centers of meristematic activity. H Population of protocorms at various stages of shoot apex differentiation (SD). G Stage 5: protocorm with extended shoot differentiation (SD). I, J Stage 5: rhizoids formed on the basal part of the protocorm became elongated. K Stage 5: seedling (S) with the first leaf (FL) emergence and the long sheath (SH) primordium initiating in its anterior part. L Stage 5: at the early seedling stage the elongation of the first leaf was observed. M, N Stage 6: seedlings (S) obtained in vitro before transplanting in soil conditions. O Stage 6: advanced seedling stage distinguished by two and more expanded leaves and the developed first secondary roots (FSR). # A, B—scale bar 100 μm; C, D, E, F, H—scale bar 200 μm; G, I, J, K—scale bar 500 μm; L, M, N, O—1 mm