The common ivy (Hedera helix ssp 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 environmental conditions – being particularly tolerant of shade.
Ivy is the only UK member of the botanical family known as the Araliaceae;a family that is more often associated with tropical regions, especially Indo-Malaysia (for further details see Mabberley’s Plant Book).
Ivy has distinctive leaves, which persist throughout the winter months.They are described as being palmate (shaped a little bit like a spread hand) with 3 to 5 distinct triangular lobes – see photo.Generally, the leaves have a dark, ‘bottle green’ colour when mature, except around the veins where the colour is lighter; young leaves may be a brighter green.The leaves are arranged alternately around the stems.
If the plant is climbing up a support like a tree or a wall, then where the young stem comes in contact with a surface it forms small, aerial roots; these help ‘bind’ the plant to that surface (see photo). However, Ivy is not a parasite in that it does not take food, minerals or water from the tree that it grows on. Apart from these aerial roots, young stems may have a downy surface –this can also be seen on the photo.
When Ivy reaches the top of a tree or wall or is in bright light, then it tends to form flowers (though late in the year). The shoots that bear the flowers have leaves that are completely different shape; these are oval or elliptical in shape.The flowers of Ivy are a rather unostentatious yellow-green colour and form late in the year (between September and November).Each has five petals and five stamens, surrounding a centrally placed stigma.The sepals are rudimentary.The ovary has 5 ovules, each one of which may form a seed.
The berry that forms often contain between 3 and 5 seeds (see photo below). This matures over the winter months, becoming black and represents a source of food for birds (like wood pigeons, thrushes etc) and their young in the Spring.The seeds are often dispersed after their passage through a bird’s gut.
Ivy is said to be responsible for certain forms of dermatitis and skin rash (in susceptible individuals), further details can be found in the Botanical Dermatology Database.Ivy has also been used in a number of ways; see this pdf file about the plants in The College Garden of the Royal College of Physicians.
Detailed botanical information on Common and the related Atlantic Ivy (H. helix ssp hibernica) can be found in the ‘New Flora of the British Isles” by Clive Stace and the Plant Heritage site (National Council for the conservation of plants and Gardens) is also a useful source of information.