Stinking hellebore is bumblebee heaven

 Stinking hellebore is an unappealing name for a very bee-friendly plant. It has been the epicentre of bumblebee activity in our garden ever since they first emerged from winter hibernation. The green flowers of Helleborus foetidus are a prolific source of nectar over a prolonged flowering period.

There used to be just one plant in the garden but three years ago I collected all the seed it produced and chucked them on ground where I'd removed a holly hedge in the corner of the garden. There are now about a dozen plants flowering, bearing hundreds of flowers. They don't really stink, they're just a bit pungent on a hot afternoon, but that's a small price to pay for providing such a good food resource for queen bumblebees.

The purple-edged, bell-shaped flowers are unusual because those structures that look like petals are, botanically, sepals that protected the bud during its formative stages. The real petals, inside, are arranged around central whorls of stigmas and pollen-loaded stamens, and are rolled into tubes that are prim-full of nectar.

The flower retains its bell-shape until its pollinated but it's just open enough to allow a large bumblebee to hang underneath and force its way in. Even then, the bee needs to have a long tongue to reach all the nectar. Helleborus foetidus makes its visitors work for their reward. 

If you plant Helleborus foetidus once and let it go to seed it will seed itself around the garden, thanks to the white extension called an elaiosome on the outside of the shiny black seeds.This is very attractive to ants, which carry them away, eat the elaiosome and disperse the seeds, which require a winter of freezing temperatures before they'll germinate. 

Himalayan balsam nectar

 Himalayan balsam is notoriously invasive and the chances of ever eliminating it on a large scale seem negligible. Even when plants are pulled up there is always a large seed bank in the soil, and flooding carries the seeds far and wide along river valleys. But it does have at least one virtue: it's a very rich source of nectar late in the year, when few native nectar-rich plants are available. Bees and wasps find it irresistible.  

The flowers have a distinctive pollination mechanism, with anthers positioned in the roof of the flower, so they deposit pollen very efficiently on the upper thorax of visiting insects, like the honeybee above and the wasp below.

Persistent insect visitors are immediately identifiable by the dense coating of pollen that they carry from flower to flower - a very efficient pollination mechanism which goes a long way towards explaining the high levels of seed production.

Some balsam nectar-addicted visitors, like the wasp above, become so heavily coated in pollen that they develop a ghost-like appearance. 

Sweat bees

I need to thank Grant Burleigh on iSpot for identifying these as sweat bees Lasioglossum sp.

They are only small - about 1cm. long - but they seem powerfully attracted to marjoram flowers. There are dozens of them on the plants in our herb patch.

When they weren't feeding they congregated on a dead shoot of the plant. There are about a dozen here and I suspect that most of them are males, with a single female in there somewhere.