Most bulbs are subterranean. Some, However are borne above the ground.

A abulb is a modified stem in which the central axis is vertical and much shortened, perhaps to ⅓ inch. The inter nodes and nodes are not easily distinguishable. the central axis has a terminal growing point and axillary buds. This would be expected since it is a modified, vertically compressed stem.A bulbs is comparable in structure to an ordinary bud which has the embryonic parts to produce a stem and also to cabbage head in which the central axis, nodes, int erodes, terminal growing point, leaves, and axillary buds are clearly evident. The fleshy modified leaves are closely oppressed. In some bulbs the modified leaves are continuous around the axis, forming a series of layers. In cross section these layers appear as concentric ring, as may observed in the onion. Bulbs of this type are known as layered or tunicate. In the other bulbs the scales are not continuous but are rather narrow and fleshy, they many be removed singly form the outer edges of the bulb. they are known as scaly bulbs, and lilies are the most important members of this groupx

Growth Cycle:
When bulbs are plated, the following growth processes are likely to occur, adventive roots develop from the4 base of the central axis, growth of the central stem at its terminal produces more leaves in the interior of the bulb, the bases of these leaves become additional layers or scales, under favorable conditions, a flower stalk is produced by the terminal growth and elongtion of the central axis, may grow and produce other new bulbs, with all the characteristics of the mohter bulb. These provide a means whereby bulbs may be incresed in numbers. The narcissus group of bulbs which includes daffodils and jonquils, comprises a group of very useful and popular flowers. The normal cycle of reproduction of the narcissus requires a period of 3 years.

The mother bulbs, as they reach maximum size, develop buds in the axis of the layers. These buds, still attched to the central stem, continue to develop, forming daughter bulds, or slasbs, which may be separated easily form the mother bulbs at the end of the growing season. These, separated and replanted each year for 3 years, become successfully larger until flower stalks are produced and the cycle of development is Complete.

In certain kin of layered bulbs the mother bulb is depleted each season of growth, and bulbs for further propagation are derived entirely from those that from from axillary buds. The tulip is an example of the bulb of this type. The formation of a large number of adventive bulblets can be stimulated in hyacinth bulbs by cutting in the basal portion of the mother bulbs to remove the entire basal planet, or cutting across the base deep enough to extend though the growing point.
The lily is the most important of the several different methods by which it can be successfully propagated.A large bulb will have from 75 to 100 scales. The when detached from the mother bulb and planted under suitable condition of temperature and moisture, will develop small bulblets on the inner, or concave, sides. They arise from adventious buds. The are separated from the scales in due time and when grown under suitable conditions, will be from 3 to 4 years. Stems of some species will produce a large number of new bulblets. They are pulled from the old bulbs and heeled in shortly after the flowers have opened. In a period of 35 to 40 days. small bullets will have formed on the base of the stem. Their origin is largely from adventitious buds. These may be removed and plnted singly, or the entires stem withe the bulbets intact may be planted horizontally to provide increased growth of the small bulbs. Vuttings of hte stems may also be made, withe three or four leaves intact, or individual leaf cuttings may also be made, with hell s or mallets of the stem. In either case, bulblets are formed from axillary buds. They are separated and grown until they reach flowering size as indicate above.

Aerial bulbils are formed by several species of lilies. They occur in the axils of the upper leaves and may be removed soon after the flowering period. The bulbis may be set in beds and allowed to grow for 2 years, which time some of them will be producing flowers.

Division of the bulb occurs under nature conditions as a result of growth of asillary buds, and small increses may be obtained by digging the bulbs at intervals of 4 to 5 years for division. In commercial propagation, one of the other methods described will give more satisfactory results.

Seed are produced by almost all the lilies, and this method has the advantage of producing immense numbers of new plants, It also a means of producing new variete4s. The growing of lilies from seed is a delicate undertaking. Seed of some species germinated poorly.

A structure very similar to bulbs is the corm, or solid bulb,
A corm is a modified stem in which the central axis has become short and compact. The entire structure, when dormant, consists of the fleshy central axis. It differs from the true bulbs in that the dormant corm is solid, without layers or scales. In cross or vertical section, the nods and very short inter nodes of a corm ar e clearly evident. Apical buds and some axillary buds are present. At maturity, dried-leaf bases, arising from the various nodes, constitute the thin outer covering.


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