The Anatomy Of The Lily
All lily plants survive over several to many years, annually sending up a new stem from their underground storage organ, the bulb. The flowers may be poised at various angles on their stalks, with one or several on each stalk. The parts of the flower come in sets of three or six, a pattern common to the family Liliaceae.
Below you can find details about the various parts of the lily plant and their functions. A typical lily plant consists of: bulb, roots, stem, leaves, and flower (inflorescence).
The lily bulb
The lily bulb is composed of firm, fleshy scales that store food for the following season's growth. The bulb consists of a short stern, or axis, to which the scales are attached. The axis, also called the basal plate, is the most important part of the bulb because it produces the roots, scales, and buds for new growth. The scales are modified leaves, much thickened and shortened; they provide nourishment for the developing plant until it has sufficient leaf area and root system to take up this task. The color of the scales is one feature by which a lily species may be identified; this color may change on exposure to light.
Lily bulbs are of two general types, concentric and rhizomatous. In the concentric type the axis retains the same shape and position each year. The bulb remains nearly concentric, with its scales arranged around a short vertical stern. The daughter bulb develops within the mother bulb and close to its axis. In some cases two or more daughter bulbs may develop around the axis and may even become separated, although they remain close together. Most European and Asiatic lilies have concentric bulbs. In species such as Lilium lankongense, L. nepalense, and L. wilsonii, the stem travels underground for some distance before emerging, bearing bulblets away from the mother bulb. This habit has been termed stoloniferous.
The rhizomatous type of bulb is best developed in the eastern American species Lilium canadense, L. michiganense, and L. superbum. The daughter bulb forms at the end of a horizontal, scaleless branch, which pushes out from the mother bulb. This daughter bulb flowers the following year and in turn produces its daughter bulb. Such lilies are usually found in wet meadow or marsh habitats where the soil is rarely disturbed; here their habit of growth allows them to seek fresh soil each year, eventually forming large colonies.
A modification of the rhizomatous type of bulb is exemplified in the western American species Lilium pardalinum and L. parryi. The stout perennial rhizome or rootstock is covered with scales. This rhizome may be as much as 2.5 centimeters (1 inch) in diameter and several years old in its oldest part. This growth habit is advantageous in the frequently disturbed soils of stream banks where these lilies usually grow, because if part of the rhizome is carried away by erosion, the remainder can still produce a plant.
The roots of lilies serve two purposes: they absorb nutrients and moisture from the soil, and they anchor the plant. The basal roots, extending from the base of the bulb, serve as anchors; they also pull the bulb deeper into the soil. The stem roots just above the bulb are feeding roots, very important to the life of the plant. Bulbs must always be planted at a depth sufficient for the development of adequate stem roots.
The stem and leaves
A mature lily's flowering stem may be as short as a few inches in Lilium nanum or other high alpine species, or as tall as 250 centimeters (8 feet), as in L. leucanthum var. centifolium or L. superbum. Some stems rise straight from the bulb, as in L. martagon and L. regale; others travel horizontally underground before emerging, as in L.lankongense and L. nepalense. The color of lily stems varies from light green to dark purple; this feature may vary even within a single population of a given species.
The leaves range from the narrow, grass like foliage of Lilium pumilum to the broad, lanceolate leaves of L. auratum var. platyphyllum. Some species, such as L. taliense, produce a naked, asparagus-like stem that rises 30 centimeters (12 inches) or more before the leaves expand.
Lilium martagon, L. hansonii, and their hybrids, as well as several North American lilies, bear their leaves in regular whorls around the stem, with gaps between the leaves. Occasionally some of the leaves are in whorls and others scattered along the stem. In most other lilies, such as the trumpet and Oriental species and hybrids, the leaves are arranged alternately. This is also the case in L. candidum and L. x testaceum, but their leaves diminish in size from the base upward.
The function of the leaves is to manufacture food, which is stored in the bulb for the following season's growth. The maintenance of this food-making part of the plant at its full efficiency for as long as possible is thus a major concern in growing lilies.
Several species and hybrids bear small purple bulbils in the axils of their leaves. If the flower buds are removed from the stem early in its development, more and larger bulbils will be produced, because this is an alternate reproductive strategy, useful when seeds are not present. The species Lilium lancifolium (synonym L. tigrinum) is well known for its bulbil production. The bulbils can produce new plants identical to the parent when they enter the soil.
The underground part of the stem may produce bulblets in certain species and hybrids. The stem roots, produced between bulb and soil surface, are feeding roots, and are very important to growth.
The term inflorescence refers to the entire part of the plant where the flowers are borne, or the flower head. The lily inflorescence may be a raceme, an umbel, or a single terminal flower. A raceme is a series of flower stalks along the stem, each bearing one or more flowers terminally. In an umbel, all the flower stalks originate from one point on the stem. Lily flower stalks, or pedicels, may be either branched or un-branched.
The flowers of lilies are quite diverse in form and color, and this diversity contributes enormously to the charm and beauty of the genus. The basic forms are turk's-cap, trumpet, and bowl shaped.
Turk's-cap flowers are pendent and have reflexed petals that curve backward toward the stalk. Some use the term martagon form for this type of flower, because the European Lilium martagon (turk's-cap lily) is a typical example.
Trumpet flowers have a variety of shapes, typically with a rather narrow conical throat that flares out toward the tips of the petals, which may reflex slightly. The well-known Lilium longiflorum (Easter lily) and L. regale (regal lily) are trumpet shaped.
Bowl-shaped flowers are more open than trumpet flowers, and the tips of the petals may reflex slightly, but not as much as turk's-cap. Lilium auratum (gold band lily) is a good example.
The carriage of the flower is another feature used to differentiate lilies. Flowers may be upright or up-facing, outfacing, or pendent.
Within the flower are six stamens, the male reproductive parts of the flower. These are composed of slender filaments, or stalks, with the anthers or pollen-bearing organs at their tips. Lily pollen varies greatly in color from species to species and among hybrids, ranging from soft yellow to dark brown. The center of the flower contains the pistil or female reproductive organs. It is composed of the ovary at the base (where the seeds form), a long style, and a three-lobed stigma at the tip (where the pollen settles).
At the base of each tepal there is a narrow groove, the nectary furrow. Nectar is secreted here to attract pollinating insects and birds. Some species and hybrids, however, lack nectaries.
The color of the lily flower is the feature most readily noticed by the casual observer. The color range includes various yellow and red pigments, but not blue.
The seed capsule
The form of the lily seed capsule differs among species and hybrids, ranging from the relatively short capsule of Lilium candidum (Madonna lily) to the long, slender capsule of L. formosanum. All lily capsules are divided into three two-part sections with papery dividing walls, inside which the numerous flat seeds are stacked like corns in a wrapper.
All lily seeds are flat. Some, such as those of Lilium auratum, have large "wings"-the papery margin that aids in wind dispersal of the seeds. Others, such as those of L. polyphyllum, have very little wing tissue. In a fertile seed the embryo (future plant) appears as a line through the endosperm, the darker mass in the center of the lily seed.