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Bee UNFRIENDLY Plants: when flowers turn toxic · Hydroponics Daily

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  Hello and welcome back to Hydroponics Daily, your go-to podcast for everything soilless cultivation.
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  I'm your host, Dr. Russell Sharp, and today's subject is putting the world of
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  pollination on its head, really.
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  We often hear about bee-friendly plants and how you should plant bee-friendly
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  plants in your garden and things like this.
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  Well, today I'm going to talk about bee-unfriendly plants and explain what this means.
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  There are a number of plants out there that are not always best for
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  the health of bees and you might think this
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  is strange this because you know bees and flowers
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  evolved together but sometimes
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  one side takes an unfair advantage so
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  first of all think about bees feeding on the nectar of
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  rhododendron plants they can build up toxins in the
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  honey that they produce and so if you are consuming
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  that honey you can actually get poisoned the concentration in the
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  chemical responsible is called graionotoxin also
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  called acetyloandromedol easy
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  for me to say it could be high enough to be toxic to humans when the honey is
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  ingested and this has led to concerns beekeepers being concerned about the plants
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  around their hives so very different to you know most honey you think local
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  honey and things like this gravinotoxin is also present in Kalmier.
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  So if you're growing Kalmier plants, which is responsible for toxicity to livestock
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  that is given the common name.
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  So this plant, Kalmier, it's got the common name lamb's kill because it kills
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  lambs and this chemical can get into the honey.
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  Other potential sources of poisonous nectar that contain honey is the strawberry tree.
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  That's native to the UK, or sorry, it's native to the British Isles,
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  but it only grows on the west coast of Ireland.
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  So to say it's native to the British Isles is a bit disingenuous,
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  but it grows in lots of places in Europe and other places.
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  It's a coastal plant, the strawberry tree, Arbutus unido.
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  It doesn't produce real strawberries, but it does produce edible crop,
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  but it can produce poisonous nectar.
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  So the problem here is that the strawberry tree, the nectar is toxic to the
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  bees themselves due to the presence of the toxic compound Arbutin.
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  And then you'll see a lot of these chemicals have complicated
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  scientific names like arbutin but actually that's just
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  a chemical named because it's the scientific name for the strawberry tree is
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  arbutus so they just need to give it arbutin to say that's the chemical from
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  that tree so it's quite simple when you realize so both strawberry tree and
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  rhododendron belong to the heather family the ericaceae and we often think of
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  like heather honey as being particularly good you know they
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  oh it's from Heathland and things like this but can actually be bad.
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  So if you're growing these plants might be best to exclude plants.
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  Bees from your glass house or your grow room they are
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  ornamental plants that are grown a lot
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  so you you know there are big growers of these ornamental plants so potentially
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  you might want to exclude bees from the growing environment especially if you've
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  got honey production nearby so that's interesting there's a sugar called galactose
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  that is excluded from tulip flowers and it's toxic to bees.
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  So who knew that tulips were not bee friendly and the mannose sugar in lime
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  trees flowers is thought to be toxic to honeybees.
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  So lime trees, they're not lime as in, you know, key lime pie or margaritas and things like this.
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  It's the lime tree that Tilia that's native to the UK, very common tree species.
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  So why would plants produce something such as nectar for a pollinator and then
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  poison them. It remains unresolved.
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  One hypothesis is that the toxic compounds are produced in such high concentrations
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  in other parts of the plants to prevent herbivory from animals eating it.
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  The plants simply cannot stop a small amount making it into the nectar.
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  A second theory or hypothesis is that the poison prevents the pollinators taking
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  too much nectar and makes them move on to another flower more quickly.
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  This is thought to be why ornamental tobacco plants lace
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  their nectar with nicotine so nicotine will
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  be toxic to bees it's a highly toxic insecticide
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  nicotine and so there is nicotine in the nectar and so the bees will move on
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  once they've consumed too much nicotine probably highly wired and focused bees
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  after they've been to the tobacco nicotiana plants um so that'll be interesting
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  i'm planting some of those next year in my garden,
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  so I'll be interested to look how absolutely wired the bees look.
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  And bees have been observed to avoid flowers producing nicotine-rich nectar,
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  and they show no signs of nicotine addiction as a human would. Oh, there you go.
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  Another hypothesis comes from studies on orchids, and many orchids are thought
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  to intoxicate or drug their pollinators, with the results being the bees slow
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  down, stumble, and take more time in the flowers.
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  And if they're doing that then they're going to dislodge more pollen by their
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  erratic movements and this could explain why other plants also disrupt correct
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  flight and movement in bees.
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  Consequently if you want to ensure a healthy bee population for pollinating
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  your garden or your grow room you might want to consider not planting those particular species.
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  Other plant species that are bee unfriendly are doubles.
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  So if you don't know what double is it's where the,
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  parts of the the petals in the
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  flower have been doubled up due to a mutation and the
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  way flowers are arranged it's all genetically encoded and so
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  they have different wills different circles so
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  the inner bits should be the female parts the the the
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  state not the stamen the stigma then
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  the anthers the male parts then the petals then the
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  sepals on the outside and things like that but in doubles
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  they've got multiple sets of petals instead of
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  the reproductive bits and if the
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  nectaries have been removed due to that mutation then the bees can't get in
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  and just having a double set of petals often means that the pollinators can't
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  access the nectaries so a lot of ecologists try and persuade people not to grow
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  doubles so i'm growing hollyhocks next year in my.
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  Alongside the tobacco plants and I
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  will be growing doubles and standard hollyhocks and my
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  theory is that there's already enough by just simply
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  planting a plant you're encouraging biodiversity so it
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  doesn't know you don't always have to be obsessed with the bees and
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  there'll be loads of other bee-friendly plants in
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  my garden as well so doubles are always
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  considered to be beyond friendly and there are lots
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  of different mutations and lots of different ornamental flowers that
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  are considered doubles and so they will be considered unfriendly
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  to pollinators other plants that are
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  unfriendly to pollinators are wind pollinated plants so your
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  conifers your grasses things like this they're not going to be friendly
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  to bees because they they've not evolved to
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  be pollinated by bees and they don't provide any reward for
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  the bees i suppose you could say like a lawn provides a
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  place for bumblebees to nest things like this but yeah
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  so think about the crop you're growing is
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  it bee friendly is it bee unfriendly is it wind pollinated does
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  it is it doubles is it a mutant flower does it
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  produce a highly active biochemical that could
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  potentially drug or poison the bee or taint its honey things like that we are
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  obsessed a bit in the uk with honeybees and presenting honeybees but they are
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  actually an alien species brought in by the romans there are lots of other native
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  bee species that we should really concentrate on protecting rather than honeybees and yeah so.
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  We can over-emphasize the importance of bees at times, but they're an important
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  part of the ecosystem. We can say that for certain.
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  So bee-unfriendly species. If
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  you know any others that you think are bee-unfriendly, then let me know.
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  Interestingly, carnivorous plants are not on that list because carnivorous plants
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  are adapted not to catch pollinators.
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  They keep their flowers above their traps on a long spike.
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  You often see with a carnivorous plant like a venous fly trap or a picture
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  plant flowers it flowers are held on
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  a spike much higher than above the the trap
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  to avoid pollinators getting trapped so they catch things like fungus gnats
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  down by the soil surface and so you wouldn't
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  actually consider carnivorous plants to be be unfriendly although
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  if a bee did go inside the trap it would get caught but
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  you wouldn't probably go in there because it's not hunting for
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  the sorts of things that the carnivorous
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  plants tricking the the things like blue bottles and
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  flyers and fungus gnats into to get you know
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  they're after meat and lay egg they're maggots and
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  on on rotting meat and
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  things like this so bees they're not concerned with rotting meat and things
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  like that so yeah that's interesting other things that
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  might be pollinator unfriendly or be unfriendly magnolias
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  any of those sorts of um plants
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  that are quite ancient flowering plants so
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  tulip tree magnolias they've evolved to
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  be pollinated by beetles where the beetle eats the
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  flower rather than gets nectar and pollen so if you were growing just loads
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  of magnolias in your garden or in you growing a tulip tree nursery and things
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  like this then they they would oh what's the sugar apple sugar apple if you've
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  got loads of sugar apples in your hydroponic setup.
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  Then they wouldn't be encouraged by bees.
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  That would be beetles, I think, are the main pollinators of sugar apples.
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  But if you know different, let me know.
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  Okay, that's been Hydroplank's Daily for today. An interesting clickbaity title, bee unfriendly plants.
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  Thank you very much for listening. Until tomorrow, goodbye.