A b s t r a c t This study, conducted in 2008 and 2012 -2013, evaluated the flowering pattern (seasonal and diurnal), the abundance of flowering, nectar, and pollen yield, and insect visitor activity for Corydalis solida (L.) Clairv. and C. cava Schweig. et Koerte. The populations occur in the ground layer of a deciduous forest (Fagetalia ordo, Querco-Fagetea class) in a natural gorge within the current area of the UMCS Botanical Garden in Lublin, Poland (51° 16' N, 22° 30' E). The phenology of Corydalis species showed distinct year-to-year plasticity (e.g., blooming period in March -April or in April -May; duration 18 -42 days). The most intensive flower opening was noted in the early morning hours (85 -90% of daily openings occurred between 6.00 and 10.00 h, GMT +2 h). The average sugar yield was similar at 4.6 kg/ha (C. cava) and 5.2 kg/ha (C. solida), but the average pollen production differed and reached 2.1 kg/ha (C. cava) and 4.1 kg/ha (C. solida). The flower-visitor interaction in Corydalis species involved both biological (early pattern of diurnal flowering, protandry, pollen presentation at the moment of anthesis) and morphological (nectar hidden in deep spur) features. Apis mellifera foragers predominated on both Corydalis species (mean of total visitors, 68.0% to C. solida; 62.5% to C. cava) and foraged mainly for pollen (82% of foragers), while bumblebee queens (mean of total visitors, 32.0% to C. solida; 37.5% to C. cava) collected mainly nectar (68.0% of foragers).

A b s t r a c tThe observations were conducted in long-term sequence studies in the years 2006, 2009, 2013, Syringa oblata var. dilatata and S. meyeri 'Palibin' bloomed from the mid May till mid June. The species are characteristic of early morning diurnal pattern of blooming, with approx. of 60% of daily instalment of flowers opened before 9.00 (GMT + 2h). Both species studied had the corolla tube 2-fold deeper during the pollen shedding phase compared to bud stage (mean = 14.9 mm ± 3.2 SD vs. 7.8 mm ± 2.8). No species effect was found for the size of anthers, for the mass of pollen produced in anthers and for the pollen viability. A constant number of 2 stamens in the flowers of Syringa species entailed the pollen yield was derivative mainly to the number of developed flowers. Therefore significant differences were noted for the pollen yield between individual shrubs (mean 0.9 kg for S. meyeri 'Palibin', and 8.1 kg/ha for S. oblata var. dilatata ).The Syringa oblata var. dilatata and S. meyeri 'Palibin' due to their attractive flowering period, and the abundance of blooming are suitable for different ornamental designs in urban areas. Unfortunately, despite the entomophilous flower traits, the insect visitors appeared sporadically.

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A b s t r a c t The flowering phenology and pollen production of three ornamental Centaurea species were investigated in the years 2009 and 2012-2013. The study objects, Centaurea montana L. = Cyanus montanus (L.) Hill, Centaurea mollis Waldst & Kit, and Centaurea dealbata Willd. were cultivated within an area of the UMCS Botanical Garden in Lublin, Poland (51° 14' N, 22° 34' E). Under the environmental conditions of SE Poland, the Centaurea species flowered continuously from mid-May to the first week of June. The mass of pollen in anthers was found to be species-related: 3.70 mg (C. montana), 4.02 mg (C. mollis), and 6.01 mg (C. dealbata) per 100 anthers. The total pollen yield was related to the mass of pollen produced in flowers and the abundance of blooming. Pollen grains were medium-sized, spheroid (C. dealbata) or prolato-spheroid (C. mollis and C. montana) in shape, and characterized by high viability (over 80% on average). The pollen provided by the plants of ornamental Centaurea species amounted to 6.0 -7.9 g per m 2 on average. The honeybee was the most frequent visitor of C. dealbata, accounting for 55.2% of the total pollinators, and bumblebee species predominated on the flowers of both C. montana (77.7%) and C. mollis (85.6%). Solitary bees and dipterans were also observed on the flowers of all species studied, but C. mollis was avoided by lepidopterans. Ornamental Centaurea species provide pollen reserves that could support communities of invertebrate pollinators, although the period of effective supply fluctuates annually due to changeable periods of blooming.

Nectar secretion was noted both in the male and female floral phases of the protandrous flowers of <em>Campanula patula</em> (Campanulaceae). Female-biased sugar accumulation was evidenced and plasticity in the duration of sexual phases observed. Flowers in the male phase produced twofold less nectar with lower sugar concentrations compared to female-phase flowers. The sugar mass content averaged 0.6 mg ±0.45 <em>SD</em> per flower in the male phase and 1.4 ±0.5 <em>SD</em> per flower in the female phase. The pollen mass averaged 0.16 mg ±0.10 <em>SD</em> per flower. An understanding of the evolution of functional relationships between floral sexes requires consideration of the compensation of the reproductive costs, including the plastic response to interdependent factors, i.e., photosynthesis and growth, the effect of pollinators, pollen robbers, and external environmental forces.