Flower morphology and sex ratios
The structure of 30 perfect and 30 pistillate flowers was studied. Flowers were collected at different stages of flowering to identify the features of their development. The morphological description of flowers is given according to Ronse de Craene (2010). The sizes of flower parts were measured using a Biomed MS-1 stereoscopic microscope with an eyepiece micrometre at magnifications of 20 and 40, depending on the size of the measured organ. Measurements were made of the main parts of the flower, characterizing the calyx, corolla, androecium and gynoecium.
The method of microscopy in acetocarmine was used to determine the quality of the pollen. All four anthers of perfect flowers were used to prepare pollen preparations. The preparation was studied under a Biomed-5 microscope at a magnification of 16 × 10. Pollen grains were counted in 30 fields of view. In each flower, 300–500 pollen grains were studied. The pollen of 30 perfect flowers of 10 different plants was studied. The determination of the size of pollen grains was carried out on the same preparations, the measurement was carried out using an eyepiece micrometre at a magnification of 16 × 40. The pollen fertility (in %) of perfect flowers was studied.
Pollen grains were counted according to the generally accepted method (Cruden 1977). In 10 flowers, the number of pollen grains in one of the randomly selected anther thecae was determined. All pollen grains of the theca were counted. A preparation for light microscopy was prepared from all its contents. We used a Biomed-5 microscope with an eyepiece micrometre with a grid to count pollen grains. Since the entire Lamiaceae family is characterized by a single fertile ovule in each ovary locule and four thecae in the anther, the pollen/ovule ratio was estimated for each flower by doubling the number of pollen grains in the theca.