(DOGWOOD FAMILY)A family of about 100 species of evergreen or deciduous shrubs that grow in temperate regions of the northern hemisphere. Leaves are usually opposite and flowers are small but often surrounded by conspicuous colourful bracts.
| ERICACEAE (HEATHER FAMILY)A large family of 100 genera and about 3,000 species found all around the world. Most are trees or shrubs and may be evergreen or deciduous with alternate leaves. The flowers are variable, but most have 5 petals joined at the base. |
| EBENACEAE (EBONY FAMILY)A large family of trees found mainly in the tropics and including the African tree that yields the black wood known as ebony. The date plums, Diospyros species, producing edible fruits, are mostly hardy in the N European climate. |
| STYRACACEAE (STORAX FAMILY)A family of about 150 species of small trees and shrubs found in E Asia, the S USA, Central and South America, with an isolated species in the Mediterranean. The leaves are simple and alternate, and the flower has a tubular corolla dividing into 5–7 lobes. The fruit is a dryish capsule. |
| OLEACEAE (OLIVE FAMILY)A large family of nearly 1,000 species, including many sweet-scented flowering shrubs such as lilacs (Syringa), and numerous large trees like ash (Fraxinus). All trees and shrubs have opposite leaves and the flowers have either 4 petals or none at all. |
| BIGNONIACEAE (BIGNONIA FAMILY)A family of many trailing and climbing plants, but the Catalpa genus from North America, the West Indies and China contains 11 tree species. |
| SCROPHULARIACEAE (FIGWORT FAMILY)A large family of mainly herbaceous plants such as the familiar foxgloves and speedwells. However, there are about 10 tree species, mainly from China, in the genus Paulownia. |
| CAPRIFOLIACEAE (HONEYSUCKLE FAMILY)A family of shrubs and small trees, many with attractive flowers and colourful berries. Found across a range of habitats. A number of species have been taken into cultivation for food or as ornamental plants. |
| ASTERACEAE (DAISY FAMILY)A large family, most members of which growing in the British Isles are annuals or perennial herbaceous plants. However, a few species do become woody shrubs. Flowers are typically numerous and borne in dense, terminal heads. |
| AGAVACEAE (CENTURYPLANT FAMILY)A family of perennials with either succulent leaves in huge rosettes, or branched and woody stems that terminate in rosette-like tufts of leaves. Flowers are borne in large spikes. Mainly from warm climates or the southern hemisphere. Grown in the British Isles, usually in mild regions, and only one species really qualifies for tree-like status. |
| ARECACEAE (PALM FAMILY)A large family from the tropics, adapted to survive in dry weather and often very windy conditions. The unusual form of growth does not enable them to branch, and the trunks do not become thicker as the trees age. Palms have a single terminal growing point from which new leaves and flowers emerge. Some are hardy enough to survive the European climate, growing in southern areas of Britain. Palms are raised from seed. |
IDENTIFYING TREES
Very little equipment is required to identify trees, but a few simple items are helpful. The first essential is a notebook in which to record observations in the field. The traditional botanists’ rule ‘Take the book to the plant and not the plant to the book’ applies to trees in that snapping off twigs, fruits or flowers should be avoided where possible; this may be prohibited, or may simply be bad manners if the tree in question is growing in a garden or park, for example. Some arboreta and botanical gardens are very firm in prohibiting the removal of living materials and may take action against a person who damages a tree. It is best if detailed notes can be made in the field, and if there are some fallen leaves or fruits beneath the tree, and it is certain that they are from the tree in question and not any other nearby trees, then these can be taken for help in identification.
Photographs are a very useful way of keeping records and will be of great help in identification. A record of the same tree in different seasons of the year would be helpful to show the changes in foliage colour and the appearance of the flowers.
A hand-lens, capable of magnifying up to × 10, is very helpful. Many features of trees, even very large specimens, are easier to see in close-up. Coniferous trees often have lines of tiny pores (stomata) on their needles, and the number and arrangement of these can be crucial to correct identification. The degree of hairiness of the leaves and petioles is often very important; some species have hairs in the form of tiny stars, while others may have fine hairs of a particular colour, both features that can only be reliably seen in close-up. The arrangement of the parts of the flowers often helps in tracing a tree to a particular family and these parts are usually quite small.
A small ruler with a scale marked in millimetres is also very useful as the measurements of needles, leaves, petioles and floral parts can be very important, although it should be stressed that these are often variable. A longer tape-measure is also helpful for measuring the circumference of trees; this information can be used to estimate the age of most trees (see p.).
ESTIMATING THE HEIGHT OF A TREE
Although the height of a tree is not a definitive guide to identification – trees grow after all – it often helps to know this measurement when deciding on a species’ identity. There are a number of simple methods that can be used with reasonable accuracy but the following is the most straightforward.
Hold a straight stick vertically in front of you, at arm’s length, and line it up with the tree. Move backwards or forwards until the stick appears to be the same height as the tree and then rotate the stick through 90 degrees until it is horizontal. Keeping one end of the stick in line with the base of the trunk, ask a friend to stand in line with the other end of the stick, along the trajectory if the tree fell over and lay at right angles to your orientation. Measure the distance between your friend and the base of the tree trunk and this will tell you the height of the tree.
Measuring tree height.
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