Lily bulbs vary greatly in shape and structure. The typical bulb is ovate or pyramidal in shape, with small regular scales. There are many variations from this. Some are more or less rounded, others, notably that of L. Polyphyllum, are very long and narrow. Some have large flat scales, whilst in others the scales are small and rounded. Some bulbs, such as those of L. Superbum, L. Canadense, and many others, are borne upon a perennial rhizome, the bulbs themselves being annual.
The bulbs of L. Humboldti and L. Washingtonianum are curiously unlike those of any other lilies, being flat and oblique. Some bulbs possess a large number of minute scales, others have but a few large scales.
The bulbs of L. Roseum and L. Hookeri are invested with a dense membranous sheath like the bulbs of the tulip. No other lily bulb possesses this sheath. These are some of the varieties of lily bulbs; an accurate description of most will be found in connection with the accounts of the various species.
The stem of the lily is usually straight and unbranched. Very rarely the stem is branched. It varies in diameter and toughness in the various species. In some species it is covered with down.
The leaves are subject to even greater variety than is the bulb. They may be few or many, arranged in whorls or scattered, and of various colours and shapes.
L. Chalcedonicum has many hundred leaves, whilst L. Auratum rarely has more than thirty. In some lilies, such as L. Washingtonianum, L. Humboldti, L. Martagon, etc., the leaves are arranged in whorls, but in most kinds the leaves are irregularly scattered.
In colour the leaves of the lilies present much variety. Usually the leaves are deep glossy green. In L. Longiflorum Foliis Albo-Marginatis the leaves are pale green bordered with white. In one variety of L. Candidum they are edged with yellow.
Lily leaves are usually linear or lanceolate; but they vary in shape from the thin pine-needle-like leaf of L. Pyrenaicum, to the broad heart-shape leaf of L. Cordifolium.
Usually but one kind of leaf is present, but in L. Giganteum at least three distinct forms of leaves are developed. And in Lilium Candidum the autumn or base leaves are totally distinct from the linear leaves borne on the stem.
The leaves of L. Bulbiferum and L. Tigrinum bear bulblets in their axils. Other lilies occasionally bear bulblets in the axils of their leaves, especially if the plant fails to flower. A bulb is only a modified bud, so that it is not surprising it should occasionally develop above ground. L. Umbellatum and L. Longiflorum are the commonest lilies to bear these aerial bulblets, except of course L. Tigrinum and L. Bulbiferum, in both of which lilies they are always present.