When is a bulb not a bulb? Quite often. The term bulb, in every day vernacular, includes corms, tubers, tuberous roots, rhizomes and stolons. I think I have them all. Except for tuberous roots which the name suggests is a root, all of them are modified stems. What makes a modified stem? A stem is made up of three parts. First the stem or branch, then the node and at each node is usually one or more leaves and buds. The bud is the required part because without it there can be no new growth. These modified stems are compressed or very short. Take a look at an onion. It comes with a basal plate which practically has no internodes. From this basal plate all the usual parts of the stem are there. The leaves or onion rings ( yum ) are attached to the basal plate one on top of the other. There are also in many cases buds at the base of each leaf. This is a tunicate bulb. Tunicate bulbs like onions, tulips, daffodils and garlic have a cover (brown like on tulips white like on garlic) with tightly attached storage leaves. There are also bulbs with a slightly different makeup like lily bulbs. These bulbs are scaly not tunicate and have no outer covering. The scales of these bulbs are large and leaflike. Bulbs allow the plant to survive an extended period of adverse conditions, usually drought. They survive by going dormant, often during the summer, or other extended times every year. This dormancy is a requirement for their survival. While dormant, the bulb rests and goes through a process and prepares to start growth all over again. In the case of many of the spring flowering bulbs that we plant in the fall, almost all of them must also go through an extended cold period to initiate growth. This new growth can be as simple as only producing roots in the fall. They will eventually, after three months of cold, poke their heads through the soil and flower in the spring even coming up through the snow. I'm looking forward to spring. That is why snowdrops are one of my favourite bulbs.
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