Collins Complete Guide to British Trees: A Photographic Guide to every common species. Paul Sterry

open in spring and summer when more insects are active.

      The fruits of trees and shrubs are much more varied than the cones of the conifers. They range from tiny papery seeds with wings, through nuts and berries, to large succulent fruits in a variety of shapes and colours. Edible fruits are designed to assist dispersal of the seeds by animals and many are delicious to the human palate.

       Hawthorn flowers are an attractive sight in spring and are irresistible to pollinating insects.

       HAZEL – NUTS

       CRAB APPLE – FLESHY FRUIT

       SYCAMORE – WINGED SEEDS

       GUELDER-ROSE – BERRIES

       The fruits of broadleaved trees and shrubs come in a range of shapes and size, including winged seeds, hard-cased nuts, luscious berries and juicy fruits.

WHAT IS A TREE?

      Nobody could have any doubt that a mature Wellingtonia or an ancient, spreading Pedunculate Oak is a tree, but would a prostrate Juniper, or a Creeping Willow, also qualify, or are they merely shrubs? One feature common to both trees and shrubs is that their stems increase in thickness each year by the laying down of internal layers of woody tissue in the form of concentric rings. This secondary thickening builds up year by year to increase the diameter of the stem and gives a permanent record of the age of the tree or shrub.

      Trees are generally considered to have a single main stem of 5m or more in height with a branching crown above this, whereas shrubs may have numerous stems arising at ground level and may not normally reach the height of a tree. Both trees and sizeable shrubs are covered in this book but the distinction is not always clear. Individuals of the same species may become trees or form shrubs, depending on the circumstances in which they are growing, or their management. Hazel, for example, forms a multi-stemmed shrub in response to coppicing, or cutting back to the rootstock; each time this is done, new shoots arise from the rootstock and the Hazel regenerates. If this cutting back does not take place, it can grow as a medium-sized tree on a single stem.

      Trees do not belong to a single family of plants; many plant families are represented, and some, like the Fabaceae and Rosaceae, also include many herbaceous plants and shrubs as well as large trees.

      The plant kingdom is divided into two main classes, the Gymnosperms and the Angiosperms. The most primitive of the two classes is the Gymnosperms, the name meaning ‘naked seeds’; the ovule is borne on a bract and not enclosed in a seedpod or case. This class includes the Maidenhair Tree, a very primitive tree, and all the conifers, or cone-bearing trees.

      The name Angiosperm means ‘hidden seeds’ and refers to the way the seeds are contained inside an ovary, a structure that may later develop into a seedpod or fruit. This large class includes many well-known plant families, some of which are mostly made up of herbaceous plants, and some of which are mostly composed of trees. The Limes (Tiliaceae) and Elms (Ulmaceae), for example, are mostly trees, whilst trees feature in only one of many genera in the Foxglove family (Scrophulariaceae). All of our garden and wild flowers, bulbs, palms and the grasses and cereals are Angiosperms.

       With their massive trunks, there is no mistaking that these Common Beeches are indeed trees.

TREE AND SHRUB FAMILIES IN BRITAIN AND IRELAND

GINKGOACEAE (GINKGO FAMILY)An ancient family, representing the precursors of our modern conifers and broadleaves, that thrived before present tree families had evolved. Only one species has survived; others are known only from fossils dating from at least 200 million years ago.

ARAUCARIACEAE (MONKEY-PUZZLE FAMILY)A family of large evergreen trees, some important timber-producers, found mainly in South America and Australasia. Sexes are separate and trees seen in Britain have been raised from seed.

AXACEAE (YEW FAMILY)A small family of primitive conifers, some being little more than shrubs, restricted to the northern hemisphere. They have poisonous seeds and foliage. Male and female flowers are produced on separate trees and the seeds are surrounded by a fleshy cup called an aril. They can be propagated by seeds and cuttings.

CEPHALOTAXACEAE (PLUM YEW or COW-TAIL PINE FAMILY)Once a widely distributed family, according to fossil remains, but now restricted to the Far East. The leaves are large, flattened needles, the male and female flowers are borne on separate plants and the fruits are plum-like.

PODOCARPACEAE (PODOCARP or YELLOW-WOOD FAMILY)A family of yew-like trees with fruits that are borne on fleshy stalks that are edible. Mainly confined to the tropics and the southern hemisphere, but some occur in Japan and India.

CUPRESSACEAE (CYPRESS FAMILY)A large group of coniferous trees widely spread around the world. Most have very small, scale-like leaves and tiny buds. The cones are small and tough, often rounded and woody, or fleshy in the case of junipers. Most are slow-growing and long-lived, giving strong, scented timber, and were mistakenly called cedars by early explorers.

TAXODIACEAE (REDWOOD FAMILY)An ancient family, once with many more representatives than the 15 species that exist today. Four species are deciduous, the others all evergreen and mostly with hard, spine-tipped leaves. The globular cones are relatively small. The bark in all species is fibrous and a rich red-brown. Some redwoods are the largest living organisms in the world.

PINACEAE (PINE FAMILY)A large family of 200 species, all originating in the northern hemisphere. Their cones are woody and composed of a spiral arrangement of scales, each with two seeds. The leaves are needle-like. The arrangement of the needles, such as being grouped in pairs or threes, or growing on short pegs, is a great help in the identification of these trees. The family includes firs (genus Abies), cedars (genus Cedrus), larches Скачать книгу В начало < 1 2 3 4 5 6 7 8 9 10 > В конец