The Broad - leaved helleborine Tolworth Court Farm

 

                                                                                         Broad -  leaved helleborine Tolworth court farm

 

 If I enter the orchid species Epipactis helleborine into my database I receive three entries:

  • Epsom Common 50 plants 25.7.04
  • Sixty Acre Wood 2 plants 15.8.21 
  • Tolworth Court Farm 156 plants 13.8.21

The broad - leaved helleborine is widespread but not common, with populations made up of widely scattered individuals or small colonies. Owing to its dull greenish flowers and its preference for shady corners, it is an inconspicuous plant. 

It can spread vegetatively, but due to short rhizomes, results in a tight clump of plants. Dispersal over a wider area must be done by seed, therefore and for the plant to set seed it must be pollinated.

According to D. Morgan 2021 (British Wildlife Vol 33 no 2) the BLH primary pollinators are the social wasps, particularly the common wasp Vespula vulgaris as its flowers are largely ignored by the other nectar feeding insects. These are insects that spend most of their time searching for arthropods on which to feed their larvae, while occasionally fueling on nectar; so pollination flights are not uppermost in its itinerary and if the plant colony is some distance from a nest, this is really left to chance.

Of key importance for pollination of isolated colonies of broad - leaved helleborine, is the distance covered by foraging wasps. There is not a great deal of information about this writes Morgan, but studies of the related German wasp shows that 50% of worker foraging was within 165m of the nest.

Further, a concoction of 100 chemicals of BLH nectar, including 6 anti - microbials, 7 attractants/odours and three narcotics (which might explain drunken wasp behaviour) Jakubska 2005. The researchers argued that the ethanol found in the nectar might be to protect the quality of the nectar and prevent fungal damage. Sluggishness and reduced grooming have been noticed on wasps that visit BLH flowers (Ehlers 1997).

 Morgan ends the item by stating: -

'The relationship between wasps and helleborines is just a single example of the vast complexity of interactions and inter-dependencies in nature but it illustrates how much is hidden to us'.

How long this colony will remain on TCF is unknown. During the second in the London Natural History Society walks in 37 degrees of heat, only 12 weakened plants had managed to survive the long hot summer.

 

                                                                       Ancient drove Tolworth Court Farm
 
 
Open fields, Tolworth Court Farm

                                                                         Veteran oak trees

 This year land along the PROW (public right of way) has been fenced, encapsulating the  oak and TPO'd ash trees (Tree Protection Orders). 


                                                                                LNHS Botany section 13.8.22


Tolworth Court Farm has always been managed for grassland species and during our walk we recorded fruiting culms of False Oat-grass Arrhenatherum elatius, Meadow Foxtail Alopecurus pratensis and other grasses wave in the breeze.  There are also traces of Meadow Barley Hordeum secalinum, with just a few fruiting spikelets left on the culms.    
  
At the edge of a belt of trees is a small patch of Fragrant Agrimony Agrimonia procera, with reflexed outer hooks on the fruits.  Agrimony Agrimonia eupatoria, with forwardly-directed outer hooks, is occasional in more open places.  Also local is Red Bartsia Odontites vernus, a hemiparasite of grasses.
 
 At the main seasonally wet spot near the A240, there's False Fox-sedge Carex otrubae, Hard Rush Juncus inflexus, Water Figwort Scrophularia auriculata, Common Fleabane Pulicaria dysenterica and other plants of marshy places – aka paludals. 
 
We watched female Brown Hairstreaks ovipositing on blackthorn. Gatekeepers, Speckled Woods, a single Marbled White and Common Blues were also seen.  See the LNHS newsletter for the write - ups from May and August walks.
 
                                                                                  Brown hairstreak TCF
 
That's what Tolworth Court Farm fields were historically  renowned for, and for the associated biodiversity. Farmland birds are in steep decline and such habitat is increasingly rare in urban areas. The farmland management was made possible with a HLS grant from Defra. At least one of the fields was not mown last year and some fields are reverting to woodland with the regeneration of hundreds of oak trees and lots of blackthorn scrub.  
 
The landscape is changing faster than ever it has in its long history, due to climate change and changes in management. So while the ancient drove is still secluded and inviting, the fields of grassland remain open  and veteran trees support jet ant and bats, what of our colony of BL Helleborines and the wasps?

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