Orange or vermillion-fruited rowan tree © Botaurus
Up to 20m tall but usually much smaller. They are slender with an open crown and spreading branches.
Divided into 11–21 leaflets.
They are 3–6cm and oblong. They are toothed in the upper half, with grey or white hairs on the underside.
They are 8–10mm across with 5 white petals, in flat or slightly domed clusters.
Globe or egg-shaped. They are usually vermillion, also orange or yellow. They always have yellow pulp.
Rowans are the pinnate-leaved species of Sorbus - the remaining species are whitebeams and service-trees. They are able to produce hybrids, which are also able to produce clones genetically identical to the parent. The result is numerous so-called ‘microspecies’ that are genetically distinct but resemble each other very closely.
A practical way of identifying these microspecies is to divide them into only two groups, based on their fruits. The first group contains all rowans with yellow, orange or vermillion fruits. The other group contains white, pink and crimson fruited species.
Rowans are among of the most distinctive small trees, especially in flower or fruit. Most species produce bright autumn colours.
The leaves and flowers of the orange or vermillion-fruited rowan tree.© Università di Trieste, Dipartimento di Biologia. Photo: Andrea Moro
Leaves and fruit of the orange-fruited rowan.© Bob Press
Orange or vermillion-fruited rowan leaves, divided into 6 or more pairs of leaflets.© Università di Trieste, Dipartimento di Biologia. Photo: Andrea Moro
Fruits of the orange or vermillion-fruited rowan.© Boris Hrasovec, Faculty of Forestry, Croatia
Orange or vermillion-fruited rowan tree.© Botaurus
These diagrams explain some of the important tree and plant parts.
These diagrams show the different leaf shapes you might come across on your survey. Leaf shapes are important for identifying trees.
The way leaves are arranged on a stem can be important for identifying trees.
These definitions explain some of the trickier words and phrases used in these pages.
Alternate – the arrangement of leaves on a stem - the leaves attach at different but alternating points, rather than opposite points.
Anther – the part of the stamen that contains pollen.
Apex – the top or end; the tip of a leaf for example.
Bract – a leaf-like structure, usually found below the flower or fruit.
Bud scale – usually a type of modified leaf that encloses and protects a bud.
Catkin – slender inflorescences made up of small flowers, usually reduced to the male and female parts. Catkins are typical of wind-pollinated trees.
Coniferous – trees that have cones, and needle or scale-like leaves.
Crown – in a tree, everything above the trunk.
Deciduous – a tree that sheds its leaves all at once in the autumn.
Evergreen – a tree that retains its leaves all year round.
Girth – the circumference of something, like the trunk of a tree.
Gland (of a leaf) – a small organ on a leaf that gives out oils or similar substances.
Inflorescence – the arrangement of all the flowers on a tree. The shape is used to help identify the plant.
Key – a tool used to identify groups and species of living things.
Leaflet – a subdivision of a leaf - it may look like a leaf but is attached to the leaf stalk or midrib, not to the shoot.
Lobe – a rounded or pointed section of a leaf, not divided into a leaflet.
Margin – the edge of a leaf.
Midrib – the central vein of a leaf.
Native – a tree that occurs naturally in an area, as opposed to a non-native tree that has been introduced.
Opposite – the arrangement of leaves on a stem - the leaves attach in pairs at the same point, opposite each other, rather than attaching at alternate points.
Palmate – a leaf shape in which the lobes or leaflets radiate from a single point, like fingers from a hand.
Petals – usually larger and more brightly coloured than sepals.
Pinnate – a leaf shape in which the lobes or leaflets are arranged on both sides of the stalk or midrib like a feather.
Pollarded – when the upper branches of a tree have been cut back to encourage new growth.
Sepals – the outermost parts of a flower which cover and protect the flower when it is in bud. They are usually green.
Side shoots – short, spur-like shoots growing from the main shoots.
Spike – an elongated cluster of flowers; a type of inflorescence.
Stalk – the structure that supports the blade of a leaf.
Stigma – the part at the end of the style. It is covered with a sticky substance that pollen adheres to.
Stipule – a small, leaf-like structure, found where the leaf connects to the stem.
Style – a tube-like structure in the centre of a flower that supports the stigma.
Trunk – the woody stem of a tree, before the branches.
Urban forest – the trees in our towns and cities.
Whorl – 3 or more leaves or needles circling around a stem.