"Narcissus scaberulus" will grow on granite soils where it is moist in the growing season but dry in the summer, while "Narcissus dubius" thrives best in regions with hot and dry summers. The "Pseudonarcissus" group in their natural habitat prefer humid situations such as stream margins, springs, wet pastures, clearings of forests or shrublands with humid soils, and moist hillsides. These habitats tend to be discontinuous in the Mediterranean mountains, producing discrete isolated populations. In Germany, which has relatively little limestone, "Narcissus pseudonarcissus" grows in small groups on open mountain meadows or in mixed forests of fir, beech, oak, alder, ash and birch trees with well-drained soil. "Narcissus" are long-lived perennial geophytes with winter-growing and summer-dormant bulbs that are mainly synanthous (leaves and flowers appearing at the same time). While most species flower in late winter to spring, five species are autumn flowering ("N. broussonetii", "N. cavanillesii", "N. elegans", "N. serotinus", "N. viridiflorus"). By contrast these species are hysteranthous (leaves appear after flowering). Flower longevity varies by species and conditions, ranging from 5–20 days. After flowering leaf and root senescence sets in, and the plant appears to be 'dormant' till the next spring, conserving moisture. However the dormant period is also one of considerable activity within the bulb primordia. It is also a period during which the plant bulb may be susceptible to predators . Like many bulb plants from temperate regions, a period of exposure to cold is necessary before spring growth can begin. This protects the plant from growth during winter when intense cold may damage it. Warmer spring temperatures then initiate growth from the bulb. Early spring growth confers a number of advantages, including relative lack of competition for pollinators, and lack of deciduous shading. The exception to requiring cold temperatures to initiate flowering is "N. tazetta". Plants may spread clonally through the production of daughter bulbs and division producing clumps. Narcissus species hybridise readily, although the fertility of the offspring will depend on the parental relationship. The flowers are insect pollinated, the major pollinators being bees, butterflies, flies, and hawkmoths, while the highly scented night flowering "N. viridiflorus" is pollinated by crepuscular moths.