Bulbs are modified stems in which the scale leaves are modified for food storage. There are two kinds of bulbs, tunicate and scaly, and they differ in the development of their scale leaves.
Tunicate bulbs, such as daffodils and tulips (see below), have fleshy, very broad scale leaves, more or less surrounding the previous leaf so that the leaves make nearly complete concentric rings around the growing point. Each scale leaf has an axillary bud. The outer scale leaves become dry and membranous and give the bulb good protection against drying and injury. The roots of a tunicate bulb develop at the beginning of its growing season on the outside edge of the basal plate.
fleshy, but are often relatively narrow. The roots are produced in midsummer or later, and persist through to the following year.
Scaly bulbs, such as fritillaries, nomocharis and lilies (see below), do not develop a dry, membranous covering and are very much more susceptible to drying than tunicate bulbs. The leaves are normally scaly and very fleshy, but are often relatively narrow. The roots are produced in midsummer or later, and persist through to the following year.
Natural bulb reproduction
Bulbs propagate naturally by division and for some this is the only way they can be propagated. In the annual growth cycle the apical bud develops and produces a new bulb during the growing season. If an axillary bud develops into an active growing point, then this also develops as a bulb that may take a year or two of further growth before it separates from its original parent (see below) and
I m\n,>1*1,111,1,11 I s,i(j;nil/,lr I. tifiniHim diul their'hybrids eventually starts flowering. In some plants, notably tulips and bulbous irises (see below), the original bulb disintegrates after flowering, leaving a cluster of small bulbs as well as a new flowering bulb. In autumn, pull these apart and plant out at twice their own depth.
Bulblets are offsets that develop on some lilies, such as Lilium longiflorum and L. bulbiferum, just below ground level either above or below the main bulb.
In late summer, gently detach any bulblets and plant the bulb and bulblets straight into the ground at twice their own depth.
Unfortunately, only a few species naturally grow bulblets in any quantity, although some other important species, such as L auratum, L. speciosum and L tigrinum, do produce a small number.
Bulbils are tiny bulbs that grow in the leaf axils of stems, which are above ground, of certain species of lily such as L. tigrinum.
After flowering time, collect the bulbils off the plant as they mature. Set them 1 in apart in a pot filled with John Innes No. 1 compost or similar (see page 12). Cover with grit and place in a cold frame. In autumn of the following year, transplant the bulbils into the ground.
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