Flowers are produced in several different ways and this has an important impact on pruning. Some species produce flowers on the current season’s growth, such as many buddleia or garden roses. In these hard pruning in the spring encourages a period of vigorous growth, leading to larger clusters of flowers. Other plants only produce them on growth made in the previous year. Many shrub and species roses produce them in this way, if they are cut back severely in the spring, there will be no crop of flowers that year.

Fruits are only made if the flowers were successful and will not be found on male-only plants. The purpose of the fruit is to grow and distribute the seeds. Some, like rowan berries, are carried in large showy clusters to attract birds to feed on them and inadvertently carry the seeds away with them. Many plants which have fleshy fruits have seeds which benefit from passing through the gut, as this helps germination. It also ensures that each seed is planted with its own capsule of nutrients; many bramble plants start life beneath the favored perches of songbirds. Others, such as sycamore or dandelion, have the seeds modified so that the wind carries them to new territory. A few are designed to stick to passing animals and to drop off later.

For good fruit effect, the plants need to flower well, including having plants of both sexes present for some species, and have sufficient food and nutrients available to develop the fruits. Potassium fertilizer will assist in the ripening of fruits. Early flowering plants, such as some fruit trees, benefit from shelter so that flowers (and thus fruits) are not lost due to frost or bad weather.

Seeds

The seed is the blueprint for the next generation. It has to be able to support the new plant until it can carry out its own photosynthesis. It also needs to be able to germinate at the right time. Many plants will germinate immediately the conditions are suitable but most have some form of dor­mancy to prevent them germinating at the wrong time. This is of special relevance in the context of weed seeds.

Stems and Branches

The purpose of the stem is twofold. It acts as the conduction tissue, between the roots and the aerial parts, for the transport of water and nutrients to the foliage and for the return passage of sugars and proteins to the roots. It also has the function of keeping the aerial parts up in the air. Young trees determine the amount of wood to make for structural needs by the way in which the stem bends in the wind; incorrect and over-staking can stop this feed­back and lead to too little stem growth.

Roots

The functions of roots are to anchor the plant in the soil and to extract nutrients and water. Roots do the former by being in contact with a large volume of soil.

Roots can only grow in soil conditions which suit them; few species will root in waterlogged or compacted soil; neither can roots grow through dry soil, although they will not die if part of the soil around them becomes very dry.

In some plants, a bacterium associated with the roots is able to ‘fix’ nitrogen from the air to make it into a form usable as a nutrient. Clover and many other legumes, as well as alders are able to do this. The bacterium receives sugars from the plant, in return for nitrogen in a form in which the plant can use it.