Like the monkey puzzle tree, the horsetails (Equisetum spp) are sometimes referred to as ‘living fossils’.  Some of their ‘relatives’ date back to the late Devonian period - about 380 million years ago.  Some were  huge and tree like, reaching a height of some 30 metres, about 98 feet.  These plants formed 'forests' and were abundant in the carboniferous period.  These ancient species persisted for some 100 million years, with some contributing to the formation of coal deposits.  Modern horsetails first appeared during the Jurassic period. Present day forms are much smaller than those of the past..  Equisetum arvense is a species that is widespread across Northern Europe and parts of America. It is a nonflowering plant, multiplying through spores. It can absorb silicon from the soil, which is unusual.  It also has the ability to take up and accumulate heavy metals such as copper, zinc, lead and cadmium.  It grows and spreads by underground rhizomes.  These rhizomes can form an extensive network, penetrating deep into the soil (sometimes to a depth of six feet).  This means the plant can be very difficult to eradicate if it appears in your garden. Techniques for removing the plant can be found on the RHS site : here.  Unchecked, Equisetum can spread extensively and smother / outcompete smaller plants. In Spring, the rhizomes produce pale, fertile shoots, topped with strobili.  Strobili are cone shaped structures that release spores. Once the spores have been released, these shoots wither and die.  Somewhat later, the non-reproductive shoots appear.  These have fine branches that appear in whorls around the ‘segmented’ stems. The whorls form at various ‘nodes’ along the stem.  These branches give the plant is characteristic form.  The name Equisetum comes from the latin Equus for horse, and setae for bristles, as the shoots have a vague resemblance to a horse’s tail.  The word arvense is also derived from the Latin where "arvum", means “ploughed”.  This references the growth of the plant in arable soil and disturbed areas.  Horsetails commonly occur in damp and open woodlands, and may also been found near the edges of streams (which may have been their original habitat). The plant has been used in herbal medicine to make a ‘tea’ or used in baths to treat skin complaints, chilblains and wounds.

Shade and stress. Shade (low light intensity) causes plants to elongate, reach up to the light to ‘outgrow’ the competition.  Such ‘elongated plants’ are said to exhibit etiolation.  However, there is a point when this strategy is counterproductive.  The plant simply cannot outgrow its taller neighbours, it is wasting resources and becoming weaker.  So plants in deep shade do not generally use this strategy.  Deep shade is detected by the phytochrome pigment system and ‘relayed' onto the plant’s circadian clock, the internal ‘daily time piece’.  This internal clock has various components and particular genes, some of which have an additional role in suppressing stem elongation (that would normally occur when shaded). Welsh woodlands and insect pollinators. A recent study across many different sites in Wales has revealed the habitats favoured by pollinators such as bees, overflies and butterflies.  The research found twice as many insects in broad leaved woodlands as compared to grassland areas.  They also found that farmlands without hedgerows had significantly fewer insects.  Both hedgerows and woodlands include trees such as oak and maple, which offer varied niches for pollinators.  They provide food (leaves) for larval stages, pollen and nectar for adults, plus egg laying sites and shelter. In Wales, there are plentiful grassland areas (mainly due to farming) with woodland only contributing 15% of land cover.  However, the Welsh Government aims to plant 180,000 hectares of new woodland by 2050.  New woodland will not only contribute to tackling climate change (through carbon sequestration) but will also do much to promote insect biodiversity. Sludge as fertiliser Sewage sludge is commonly spread across farmland as a form of fertiliser (throughout Europe).  Sewage sludge is the residual, semi-solid material that is the ‘by-product’ of sewage treatment of industrial and / or domestic wastewater. Sometimes, referred to as biosolids. It is a sustainable / renewable source of nutrients and reduces material going to landfill or incineration. The use of sludge has attracted attention as it can contain: Breakdown products of various medical / pharmaceutical that have been excreted / eliminated from us and / or animals, such as hormones, antibiotics, various drugs Heavy metals such as lead, cadmium, arsenic  Industrial chemicals / breakdown products PCB’s, dioxin Now, research at Cardiff University has shown that micro plastics in sludge are a problem; these are plastic particles less than 5 mm in size. It estimates that between 31,000 and 42,000 tonnes of micro-plastics are applied to European soils each year.  They are a threat to wildlife as they are easily ingested and can carry / contain toxic chemicals and may pass along the food chain.  The UK was shown to potentially have the highest level of microplastics in its soils, followed by Spain, Portugal and Germany.  

The vibrancy and gaudiness of sunflowers is one of the delights of summer.  The common name "sunflower" generally refers to Helianthus annuus, whose round flower heads look like the sun.  Sunflowers are cultivated as food crops for humans, cattle, and poultry, and also for the garden. They typically grow during the summer and into early autumn, with the peak growth season being mid-summer. A field of sunflowers is a welcome relief from the acres of oilseed rape. The flower of a sunflower is not a flower but hundreds of small flowers (florets) massed together the better to attract pollinators.  The structure so formed is known as a capitulum.  The inner florets are arranged in spirals that conform to fibonacci sequences.  The pattern of these florets has been described mathematically by Helmut Vogel and it allows for the most efficient ‘packing’ of the florets in the ‘flower’ head. Before the flowers open,  the plants tilt during to face the sun, gaining more light for photosynthesis. This movement is known as heliotropism  and continues for a while when the flower head opens. This may help to attract pollinators.  Frequent visitors to sunflowers are bumblebees.  Sadly, like honey bees, bumblebees face a number of problems which include parasites.  However, recent research in the United States suggests sunflowers can help certain species of bumblebee.  If sunflower pollen is included in the diet of the common eastern bumblebee then it helps reduce infection by a parasitic protozoan Crithidia bombi.  This is a parasite that lives in the gut of bumblebees. When they pass out of the gut in cysts, they can be ‘picked up’ by the next passing bumblebee (or another insect, as the parasite is not too fussy). Once established in a bee, the parasite can affect the ovaries.  If a  queen is infected then the reproductive success of the colony is affected. Giacomini et al. have found that good nutrition is vital for bumblebee health and that sunflower pollen can be a huge benefit when it is included in the diet. They noted that the majority of the bees that consumed sunflower pollen had no detectable infection a week later. The pollen* significantly reduced infection by the parasite. So sunflowers are a visual feast for us, and an edible one for bumblebees and bees.  They also provide us with seeds.  The seeds are rich in monounsaturated and polyunsaturated fats, notably linoleic acid. The seeds also contain phytosterols which may contribute toward lowering the level of blood cholesterol.  The seeds may be pressed releasing sunflower oil, and the remaining ‘cake’ can be used as a protein rich animal feed.  The Ukraine and Russia are the top producers of sunflower seed. A somewhat different use of sunflowers is phytoremediation; using plants to remove toxic organic or inorganic compounds from soil.  After the disaster at the Chernobyl nuclear reactors in 1986, an exclusion zone with a radius of 30 km centred on the nuclear power plant was created. This was later expanded to include other heavily irradiated areas.  Even now, no one lives in the exclusion zone, but scientists and others may ask for permits to allow them to enter for short periods.  Fields of sunflowers were planted to ‘harvest‘ the radioactive metals (notably caesium-137 and strontium-90) from the soil. The sunflowers accumulated these elements in their tissues.  When the sunflowers had completed their growth, they were harvested and burnt, leaving only the radioactive ash behind. This material could then be vitrified (incorporated into glass) and stored underground in a shielded container. In Brazil, a study looked at the ability of different sunflower cultivars to remove nickel, copper and lead from contaminated soil.  Though phytoremediation with sunflowers proved to be an efficient and low-cost method for the treatment of contaminated soils, the cultivars varied in their ability to take up particular metals. “Cleaning up’ with sunflowers was tried after a tsunami hit the Fukushima Daiichi nuclear power station in Japan.  However, it was not very successful.   As different cultivars vary in their capacity to hyperaccumulate, so it is important to match the cultivar to the situation. Planting sunflowers in this case did little to improve the situation. This could be in part due to the sunflowers but also be associated with the soil type and the time that the caesium has had to bind to the soil particles. Understanding the mechanisms and detail of hyper accumulation is critical if sunflowers are to be used for phytoremediation in the future. Pollen is rich in secondary plant metabolites e.g. flavonoids, terpenoids, alkaloids, amines, and chlorogenic acids [caption id="attachment_35695" align="aligncenter" width="650"] field of sunflowers[/caption]  

Nitrogen pollution, in the form of nitrates, ammonia and various oxides of nitrogen, is a threat to ecosystems, ecosystem services and biodiversity.   Monitoring and measuring such pollutants in rain and air borne particles is expensive and, ideally, needs frequent samples. It has been estimated that some 400,000 tonnes of airborne pollution are deposited over Britain each year.  Research by Dr H Harmens et al at the Centre for Ecology and Hydrology (Bangor) has indicated that there may be a simpler and cheaper way of gauging nitrogen pollution  - through the assessment of the state of local moss populations. Read more...

Plants take up essential nutrients (nitrates, phosphates, potassium, magnesium etc) through their roots, but some also take up other, more unusual substances – such as silicon, nickel, cadmium, copper, cobalt. Grasses, in particular, are known to take up silicon and then deposit it in their leaves.  The silicon that they absorb is converted into tiny granules called phytoliths, which are often located under the waxy cuticle.   Read more...