At this time of year, certain plants play an important  part in Christmas celebrations.  One is the Christmas Tree itself - which became established in Victorian times after Prince Albert introduced one in the Royal Household.  A Christmas tree is invariably a conifer but any of the following species may be used : Norway Spruce Picea abies Silver Fir Abies alba  Nordmann Fir Abies normanniana Scots Pine Pinus sylvestris and in North America Douglas Fir Pseudotuga menziesii  and Balsam Fir Abies balsamea. There is also the artificial Christmas tree. These originated in Germany in the late 1800s, and were typically made from dyed goose feathers attached to a central pole / wire frame.  Later in the 1930s, the Addis company used the machinery for making their toilet brushes to create ”trees’ .  Animal bristles, dyed green, were used to form the needles of the ‘trees’.  Nowadays, most of the artificial Christmas trees come from China. Apart from the Christmas tree, there is also Holly, Ivy and Mistletoe. All are evergreen plants.  Bringing greenery is an age old tradition associated with the coming of, or ‘rebirth’ of Spring.  The holly tree is either male or female, and also not a conifer. The leaves have spines and a thick, protective and waxy cuticle. Its leaves (as a garland around the door) were thought provide protection for the home, warding off evil spirits.  It was also used in the ancient Celtic Festival of Beltane to welcome in summer. It is certainly the case that in the past, the distribution of holly was far more widespread. The Needwood Forest in Staffordshire was a significant and ancient midlands forest but after the Enclosure Act of 1803, large numbers of its trees were felled.  In his ‘Plant Book’, Professor David Mabberley notes that some 150,000 holly trees were taken from this forest to provide bobbins for the cotton mills of Lancashire.  Bagot’s Wood is said to be the largest existing piece of this ancient woodland). Holly was also an important species in hunting estates and deer parks. Sometimes it was planted around saplings of other more valuable trees to deter browsing by deer. The  leaves of Holly are palatable to livestock, despite their spines.  It is the only evergreen tree (found in deciduous forest or woodland) that does not contain chemicals that are toxic to sheep or cattle. For many centuries, it was common practice to provide holly as fodder for livestock, during the winter months when other foodstuff such as hay or grains were in short supply.  Without the provision of the holly, livestock might have to be slaughtered.  The practice of using holly as fodder was more common in areas like Cumbria, the Welsh Borders and the Pennines*. Again in the past, Holly was also for hedging as it was virtually impenetrable, though the downside of using holly was its relatively slow growth. The berries of holly are attractive food to some birds, especially redwings and fieldfares. Holly and Ivy are often used to make festive wreaths and garlands. Common ivy (Hedera helix) may be found growing in woodlands, hedgerows or on walls. Sometimes it is a climber; sometimes it forms a layer at ground level.  It is a woody, evergreen perennial that is distributed throughout much of the British Isles, and many parts of Europe. It can grow in a variety of soil types, and when mature is resistant to many harsh conditions, being particularly tolerant of shade. Last of the Christmas plants is the mistletoe. Mistletoe is well known for the custom of “kissing underneath the mistletoe”. It is an unusual plant in that it is a hemiparasite that grows on trees such as apple, lime, poplar and hawthorn.  It forms large balls that are suspended  from the branches and and more obvious in the winter months (see featured image), when the host has lost its leaves.  Whilst it can make sugars and other complex organic compounds, it relies on its host plant for water and mineral salts.  It does this by forming ‘clamp-like’ connections (known as haustoria) with the water conduction tissue (xylem tissue) of the host plant.Mistletoe is an important species on woodlands. Some species are directly dependent upon it, or example the mistletoe marble moth and the 'kiss me slow weevil', and the berries provide food for number of different birds.    When mistletoe is removed from woodlands,  the number of woodland birds tends to decline as does biodiversity.  

Orchids are unusual, indeed exotic plants. After they have produced their flowers and they have been pollinated, the flower wilts and the ovary begins to swell to form a seed pod.  The time it takes for a seedpod to mature varies from species to  species, it may take eighteen months for a type of slipper orchid [Paphiopedilum].  When the capsule is mature, it splits open and its numerous, minute seeds are dispersed by the wind.  A single seed pod may contain millions of the dust-like seeds; a single seed may compared to a ‘speck of dust’.   Unlike the seeds of ‘normal’ plants, the seeds have no food reserve within them and in order to grow, they have to establish a symbiotic relationship with a specific mycorrhizal fungus.  This symbiosis is essential for the seed to germinate and grow.  The fungus enters the seed and provides the necessary nutrients for its development into a seedling. Propagating orchids from seeds is a complex process. sometimes done under sterile laboratory conditions using special culture media. In the wild, although an orchid may produce millions of seeds, only a minute fraction will successfully establish a symbiotic relationship with the correct fungal partner to grow and survive. Recent research with the orchid Cremasta variabilis has revealed some interesting facts about the germination of the seeds.  The orchid is found on the Korean Peninsula and is an insect pollinated, terrestrial orchid.  As with other orchids, its seeds are minute and are known to depend on a certain fungus to grow and develop.  In the past, most studies have focused on the fungi present in mature orchids but the team from Kobe University studied very young seedlings.  They noted that seedlings were often to be found near decaying logs, and this led them to test whether deadwood fungi are involved in early orchid development.   They buried seeds of four species of orchid in various forest locations, but they only observed germination  and seedlings near to decaying logs.  The seedlings were found to be exclusively associated with wood decaying fungi.  It may be that the orchids use other fungi to maintain the symbiosis as the deadwood dries out or is exhausted of nutrients. Some species of orchids have abandoned photosynthesis completely, and feed via fungi through their lives - a phenomenon known as mycoheterotrophy.  As woody (and rotting) debris represents a major carbon source in forests, it is a resource waiting to be exploited.  

Scientists from the Meteorological Office use radar data to track approaching storms and changing weather patterns.   The radar works by sending out pulses of microwaves, these bounce off rain drops and other particles in the air.  The time that it takes for this signal to return, plus its intensity gives information about the approaching weather. Early radar [during the Second World War] also picked the movement of ‘angels’. These ‘angels’ were later recognised as the movement of birds, bats and insects.  Scientists then had to develop techniques to remove this ‘biological scatter / material’, so that they could accurately predict storms etc. By removing this ‘biological component’ of the signal, a lot of biological information about the movement of birds, bats and insects was being ‘discarded’.   Now, scientists from the University of Leeds have ‘repurposed’ the radar data (from many radar stations, which scan the skies many times each day & night) but this time they remove the data relating to the weather.  This leaves information about the insects moving at a height of some 500 / 700 metres above the ground.  The results showed that some 11.2 trillion insects are moving during the day, and that this reduces to some five trillion at night.   Some of these insects are actively flying, but some are being carried by the wind  / thermals.  Furthermore, there were more insects above areas such as woodlands, grasslands and even urban areas.  However, the numbers were lower over intensively farmed areas, where plant biodiversity was reduced as compared to woodland or natural grassland.  The numbers were also lower where artificial lighting was high.   Other work by the CEH, Newcastle University and Butterfly Conservation, has involved surveys of grassland and hedgerows in southern England (Thames Valley) some of which were lit by streetlamp, others were unlit. The areas that were exposed to night time lights had roughly half the number of caterpillars as compared to the unlit areas.   In another study, LED lighting was set up in fields, and caterpillars' numbers in these illuminated fields were reduced.  The lighting may :- [caption id="attachment_40185" align="alignleft" width="300"] Cinnabar moth caterpillar.[/caption]   Deter nocturnal moths from egg laying. Make the night flying moths ‘easier targets’ for predators (such as bats). Affect the feeding habits of moth caterpillars. Whilst it would seem that night time light affects insects and the feeding behaviour of caterpillars,  quite how and why is yet to be determined.