Helleborus foetidus
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Helleborus foetidus |
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Helleborus foetidus is a perennial herb widely distributed in western Europe. In the Iberian Peninsula, the species typically grows in the understory of deciduous and mixed forests. Plants consist of one or a few ramets that develop a terminal inflorescence after several seasons of vegetative growth. Each inflorescence generally produces 25-100 flowers over its 1.5-2.5 month flowering period, but these open gradually and only rarely are there >2-5 flowers simultaneously open in each inflorescence.
Flowers are hermaphroditic, self-compatible, extremely long-lived (up to 20 d), and are pollinated by medium- and large-sized bees, mainly bumble bees and anthophorid bees. Although the species is self-compatible and a small proportion of flowers set fruit in the absence of pollinators via spontaneous self-pollination, insect pollination is required for abundant seed production. Despite the extremely low pollinator visitation rates, fruit set of H. foetidus flowers is not pollen limited, which may be explained by the long duration of flowers (click here for details).
The floral nectaries, which are deeply hidden inside the globose corolla, provide abundant nectar to floral visitors (see here). The dense populations of yeasts that quite often build up in the floral nectar degrade it by depleting its sugar content (click here for more details). Yeasts are brought to floral nectar in the tongues of visiting bumble bees, the species' main pollinators (see here).
Flowers and developing fruits are frequently eaten by mice (mainly Apodemus sylvaticus) and generalist lepidopteran larvae (mainly Trigonophora flammea; Noctuidae), which may collectively destroy or seriously damage up to 75-100 % of flowers and/or developing fruits over the flowering and fruit growth period. The green, persistent sepals contribute resources to the development of seeds through photosynthesis (see here). Fruit maturation and seed shedding take place in June-early July. Seeds have a well-developed elaiosome, and are dispersed by ants after falling to the ground (see here). Seeds have an extended dormancy, the vast majority germinating during the second spring after entering the seed bank.