Leaves have three main parts:  The petiole, a stalk-like structure that connects the blade of the leaf to the stem of the plant. Some leaves don’t have petioles,  and are known as sessile leaves. The blade or lamina, usually the largest part of the leaf.  The edge of the leaf or the leaf margin may be described as entire, toothed, or lobed. The oak leaf, for example, is clearly lobed. The blade has many veins, forming a network, carrying water and nutrients, The base, the base is the region of the blade that attaches to the petiole. A leaf is said to be simple if its blade / lamina is undivided, if the ‘teeth’ or lobes do not reach down to the main vein of the leaf.  A compound leaf has several leaflets, which join up with a single leaf stalk or petiole. When identifying tree leaves, it is always important to look for the petiole,   as a single leaflet of a compound leaf can look like a simple leaf.  More details of leaf and tree structure can be found on this link on our website. Now for a challenge.  Can you or your children find a leaf (and name the tree it came from), that Has a serrated / toothed edge Has a lobed margin Has a smooth edge / margin Is a compound, palmate leaf Is a compound, pinnate leaf Is hairy Is not green, but red or a mixture of colours Is more or less circular Is fleshy / succulent Has spines on its edges Is needle shaped Has a thick (waxy?) cuticle or is very shiny Has net venation  is marcescent (might keep you hanging around) Go forage!

The terms ghosts and zombies often feature in films or TV programmes, but across the country the terms can also be applied to many hundreds, possibly thousands of lost and abandoned ponds.  Ponds have featured in the landscape for centuries or millennia.  Pingos -  formed in the depressions left after the last ice age. The middle of the C20th saw not only the destruction of many hedgerows, but the removal of many ponds.  This was particularly true in farming areas like East Anglia.  The strategy was to increase field size and allow access of complex machinery that was becoming available at that time; for example large combine harvesters.  Whilst the loss of the hedgerows and associated wildlife is well documented, the loss of ponds has not attracted so much attention.  Many hundred of ponds were filled in (often using the debris and material from the destruction of the hedgerows), to give a few more metres of arable land, and with machinery replacing horses the need for ‘watering holes’ diminished.  The infilled ponds are sometimes referred to as ghost ponds.  The location of these 'ponds' can sometimes be found  By studying old ordnance survey (or tithe) maps or  They may be visible using aerial photography / drones and picking up a different colour or shade of the crop growing in a field Noticing the accumulation of water after heavy rain in a slight depression, or a mist hovering over a particular part of a field A zombie pond is somewhat different.  It is a pond or very wet, marsh area which is shadowed by a tree canopy.  The pond has filled over many, many years with dead leaves, so that it has a deep layer of decomposing organic material.  The pond margins is generally overgrown, with willow and other vegetation where have begun to ‘invade’.  The pond is half dead / half alive, hence the term 'zombie'.  The area / water becomes anaerobic / anoxic, as the dead leaves rot and use up oxygen. Few life forms call it home - perhaps midge larvae or the occasional beetle. Indeed, such ponds may release not only carbon dioxide but also methane; the latter is a particularly potent greenhouse gas.  Zombie ponds may be found in woodlands, particularly where active management has fallen by the wayside. However, not all is lost, both ghost and zombie ponds can be resurrected.  In the case of ghost ponds, the infilling material / soil is dug out until the original base layer is reached.   This may be recognised by the dark, fine silt layer / sediment, which may contain the remnants of water snail shells.  Ideally, the excavation should mirror the original outline of the pond.  This may be determined in part by digging two trenches at right angles to each other. Details of the restoration procedure may be found here.   Freshly excavated ghost ponds should be left to fill with rainwater through the winter months, and left for plants and animal to colonise naturally.  Amazingly, several pond restoration projects have demonstrated that the original silt layer of the pond is a valuable seedbed of many aquatic and emergent plant species, even though the seeds may have lain there dormant for decades , possibly centuries.  The refreshed pond should also have a surrounding margin of land to separate it from any adjacent farmland activities - to prevent nutrient run off / pesticide application etc.  Further details of the restoration of lost ponds can be found at:- https://norfolkponds.org/ https://www.ucl.ac.uk/geography/news/2023/nov/bringing-ghost-ponds-back-life https://www.essexwt.org.uk/recovering-lost-ponds In the case of zombie ponds, there is a similar approach to restoration but it begins with the cutting back and / or removal of trees from around the pond to let light in.  Then the layers of rotting leaves / organic materials are scooped out, so that the original sediments of the pond are exposed.  The depth of the decomposing material may be quite significant.  However, with light pouring in and the rotting material removing the pond can soon develop a diverse community of plants (from the seedbed and pond 'visitors' e.g water-crowfoot, stoneworts, and animals).  The restoration / renewal of ponds in fields, meadows or woodlands makes a significant contribution to the biodiversity of an area. There is an excellent video about the restoration of ghost and zombie ponds on YouTube, featuring Professor Carl Sayer (UCL). Professor Sayer grew up in Norfolk, where many of these ‘hidden’ / lost ponds are to be found.  Visit the Razor Science Show “Bringing 'ghost' and 'zombie' ponds back from the dead”. [https://youtu.be/SYkbDdaUMBY?si=gd2jbfxk4iXLSFL5]  

Climate change is introducing disease to new areas as it favours the spread of disease vectors, such as mosquitoes.  Usutu is a virus disease that originated in South Africa, it is spread by mosquitos and affects birds, particularly blackbirds and owls.  Whilst birds are the primary hosts to the virus, it can infect ‘incidental hosts’ such as bats and humans, through insect bites. The virus has been found in a number of mosquito species in Africa and Europe.  In the U.K,  and Europe the main vector is Culex pipiens - the common house mosquito or northern house mosquito.  The virus has probably spread through the movement of migratory birds between Africa and Europe, and is now present in many European countries. The virus was first detected in the London area in summer 2020 and was associated with a decline in Blackbird numbers. Blackbird numbers have declined by approximately 40% since 2018. The virus was then detected in Cambridgeshire in 2023.  It seems that most Usutu infections in humans do not cause disease and so the risk to human health is considered ‘low’.  There is no evidence to date that the consuming poultry poses a risk to our health.  However, the detection of Usutu in the UK marks the first time that a mosquito-borne virus capable of passing  from animal hosts to humans has emerged in this country.  Its speed and spread are being monitored as it may model how other mosquito borne disease arrive here. A virus that may be a particular cause for concern is the West Nile virus.  This virus spreads in a similar way to Usutu and needs similar climatic conditions.  West Nile virus, also transmitted through mosquito bite, can cause fever, vomiting and diarrhoea.  At present, there is no vaccine available.  West Nile virus was detected in the Netherlands in 2020, and there is concern that the changing climate could facilitate its spread in Europe.

A plant growing in the wrong place is sometimes described as a weed, but it can be more than just an inconvenience.  Plants in the wrong place can have a devastating effect on ecosystems, dramatically reducing biodiversity.  The same is true for certain animals - those that have 'traveled' from their natural habitats to 'foreign areas’ where they have no natural predators to keep their numbers in check.  Foreign or alien species are sometimes introduced to an area in the belief that they will solve local problems with pests or over-population of a native species.   A classic example of this is the cane toad.  Native to  parts of central and South America, the cane toad is preyed upon by a variety of animals such as caimans, snakes, eels and some fish species.  It was introduced into sugar plantations in various parts of the world to control beetles that were damaging sugar cane crops. Since this was a successful strategy in Puerto Rico, the toad was introduced elsewhere, notably Australia.  Just over a hundred toads were released in Queensland in 1935, with more released in 1937.  Unfortunately the toad did not effectively control the grey-backed cane beetles (the intended target), and they found other things to eat.  Their numbers grew exponentially and they spread into other areas, such as the Northern Territory and New South Wales.  These poisonous toads have significantly reduced biodiversity particularly affecting native amphibians and reptiles. Sometimes foreign species are introduced as ornamental plants or 'exotics'. During the Victorian period many plant species were brought to the UK for country estates.  Rhododendrons that were collected across Asia and the Himalayas became popular in parks and gardens.  However, Rhododendron ponticum, a species native to the southwestern Iberian Peninsula (parts of Portugal and Spain) and the southern Black Sea Basin (parts of Bulgaria & Turkey)  has been less well received.   It was introduced in the eighteenth century by Conrad Loddiges.  Loddiges grew seed and sold on young plants as an ornamental flowering shrubs for gardens, parks and estates. On country estates and heathland areas, it was planted as cover for game birds as its dense growth offered shelter and protection. It has since spread aggressively and is now considered to be an invasive species. An invasive species is a non-native species that spreads and damages its new environment. R. ponticum poses a threat to key woodland ecosystems, such as Atlantic Oak Woodland.  When this shrub ‘invades’, it comes to dominate the area.  It creates deep shade so the woodland floor becomes a dark and ‘barren’ place. Many ground flora species are lost so that only shade tolerant mosses and liverworts remain.  These plants form a ‘dense mat’ of vegetation that is a barrier to seed germination.  Additionally, there is evidence that as R. ponticum grows, it produces chemicals which inhibit the growth of other species.  This phenomenon is known as allelopathy.  Even when the Rhododendron is removed, it is difficult to reestablish the original flora.  Clearing an area of this plant is difficult and expensive. One effective method involves drilling the stems and injecting herbicide directly into the plant, a targeted approach that uses a lot less herbicide than spraying.  Mabberley’s Plant-book notes that the cost of eradicating the plant from Snowdonia was £30M and that was in 1988. Another Victorian introduction was the grey squirrel. Native to North America, grey squirrels were first released in the UK in the latter part of the 19th century.   One person associated with their spread was the 11th Duke of Bedford  (Herbrand Russell).   He was involved in various animal conservation projects, but he released and 'gifted' many grey squirrels from the estate at Woburn.  The populations of grey squirrels in Regent's Park, London are thought to have come from there. Humans may still be helping the spread of the grey squirrel, albeit unintentionally.  One squirrel was captured on the Isle of Skye (in 2010), it had traveled from Glasgow, as revealed by its genetic profile.  It had probably made the journey as stowaway under a car bonnet. It is important that we are aware of how 'easy' it is for these animals to travel with us.  Their introduction has been disastrous for the native red squirrel populations, due to competition and the spread of the squirrel pox virus.  It is vital that grey squirrels do not colonise areas where the red squirrel still survives. . More recent introductions have arrived due to increased global trade.  Parasites and pests can ‘hitch a ride’ with people, materials or goods as they move across the world.   Climate change is also altering the range and distribution of many plant and animal species.  There is an alert for the Asian or Yellow Legged hornet (Vespa velutina nigrithorax), an invasive, non-native species from Asia.  This hornet preys upon honeybees and other beneficial insects such as hover flies and bumblebees. It hovers outside bee hives, waiting to catch and then kill returning honeybees. The effect on bee colonies can be devastating. The Asian Hornet arrived in France in 2004 (through an import of Chinese pottery) and has spread rapidly. Now it is found in Italy, Spain, Portugal, Switzerland, Belgium and Germany.  Preventing its establishment in the UK is critical.  Any sighting needs to be reported, this can be done through the Asian Hornet Watch. This link downloads a PDF, which gives more information about the Asian Hornet, and contains images comparing the  appearance of the asian hornet, the european hornet, the wasp and honey bee. Other invasive species that are a cause for concern include : Himalayan Balsam Harlequin ladybirds, Signal Crayfish, Eight-toothed bark beetle Citrus long horned beetle Giant Hogweed Thanks to Anton for images.