We know that forests are important to all life on the planet.  They have often been referred to as the ‘lungs of the earth’, a reference to the fact that they produce vast quantities of oxygen - which is essential for respiration for so many forms of life.  They also take up carbon dioxide and ‘fix’ it into complex organic molecules - from starches, to cellulose and lignin.  Thus, the carbon is locked away for months, years or even millennia.  The equatorial forests of Brazil and Sumatra are species rich, incredibly diverse, but deforestation and the expansion of agriculture are threats to many biodiverse, forested areas across the world. As so many forests and woodlands have been felled, there is now a movement to plant millions and millions of trees (across the world) in an attempt to mitigate climate change and in the UK to increase our percentage tree cover from a pretty low base.  Sadly, twentieth century forestry in the U.K was largely based on monocultures (for timber production). The trees planted were large stands or plantations of conifers - using Scots Pine, Larch and Spruce. These plantations not only lacked biodiversity, but were / are susceptible to wide scale pest infestation and extreme weather events.   Woodlands and forests that have a diverse range of tree species are not only healthier but show greater growth and carbon fixation. They are more resilient.  The diversity of trees ensures the each species accesses slightly different resources from the environment  - from soil minerals, water and light.  Diversity means that trees of the same species are less likely to be clustered together so pest and pathogen outbreaks are less common or less severe.  One area that has undergone an extensive and diverse planting regime is Norbury Park Estate (near Stafford).  Since 2009, over 100 different tree species have been planted, and the woodlands can now produce 1500 tonnes of new wood each year, and harvest 5000 tonnes of carbon dioxide from the air.  Not only can diverse woodlands / forests fix carbon, supply harvestable timber but they also offer areas for rest and relaxation. Whilst it is not possible to plant an 'instant' forest or woodland, it is possible to plant a range of tree and shrub species that will in time grow and mature to form a diverse and species-rich area.  As Charles Darwin said many years ago “more living beings can be supported on the same area the more they diverge in structure, habits, and constitution” [On the Origin of Species by means of Natural Selection, 1859] Managing woodlands for wildlife - see here.   N.B.  Opens a PDF.    

Some flowers are open during the day, ready to receive visitors (pollinators) but close up each night at dusk; for example, crocuses, tulips, poppies.  Other plants move their leaves in response to light and dark. Such movements of flowers and leaves are known as nyctinastic movements. The reasons for these movements are not particularly clear / obvious. A number of suggestions have been advanced : The closing of the petals at night might serve to keep pollen dry.  When wetted, pollen is heavier and less easy for insects to distribute. By closing at night, the nectar and pollen is protected from unwanted visitors.  Some insects are nectar robbers that is they take nectar but do not contribute to pollination. Darwin made the suggestion that the closing might help protect the floral organs from the chill of night time temperature. Leaves may move to help capture rain, closing down at night to allow water to trickle down to the roots (?). Different explanations may apply to different plants but these movements have a common underlying mechanism, namely phytochrome.  Phytochrome is a blue-green light absorbing pigment. It responds to red (in the region of 660 nM) and far red light (>730 nM). Red light is generally abundant during the day, but the balance between red and far red shifts towards the end of the day. This change is detected by phytochrome and it directs the plant’s circadian / daily rhythm.  Phytochrome is involved in many processes during a plant’s life cycle from germination to flowering.  The nyctinastic movements of plant parts is, however, largely controlled by the movement of water into and out of cells - cells can swell or shrink.  Some plants have special structures called pulvini to control the movement of leaves.  Pulvini are found in the bean family (Fabaceae), and plants like the sensitive plant (Mimosa pudica) and the Prayer plant (Maranta sp).  Pulvini are usually located on the leaf stalk (petiole). A pulvinus is a small swelling on the stalk, it has a central core of vascular (water-conducting) tissue surrounded thin-walled cells (parenchyma tissue) with large fluid-filled vacuoles.  The flow of water in and out of the vacuoles of these cells raises or lowers the leaf stalk / leaf. [caption id="attachment_36023" align="aligncenter" width="650"] Pulvinus on sensitive plant[/caption] [caption id="attachment_36032" align="aligncenter" width="650"] Young Mimosa pudica[/caption]  

Plants climb in a number of ways.  Some wrap themselves around other plants, others are ‘sticky’, and some curl.    Some, like honeysuckle, use their stems, whilst others make use of their leaves to wrap around other plants or nearby supports. Twining stems twist around whatever they touch, be it a branch or an artificial structure.  Depending on the species of plant, the stems will wind clockwise or counterclockwise around the support.  Some wrap themselves around the supports so strongly that they risk damage to the supporting plant / structure.  Honeysuckle has thin, green and pliant stems when young but can form very thick, woody, rope-like stems (see featured image) as it matures.  Bindweed or Convolvolus has a thin, green stems which grow surprisingly fast around almost anything that they touch. Read more...

Mediaeval scholars used to refer to the primrose as ‘prima rosa’ or the first rose of the year.  The term ‘first rose’ is a misnomer as the primrose does not belong to the Rose family, but to the Primulaceae - a family that includes some 68 plant genera.  The common primrose is of botanical interest as its flowers occur in two forms - a phenomenon known as heterostyly or dimorphism. The two forms of the flower are known as pin and thrum eyed forms.  In the thrum eyed flower,  the long stamens are visible (see featured image above) and the short stigma lies below them; whereas in the pin eyed flower the stigma projects above the shorter stamens (see image below). Read more...