What's
Happening Underground?
— Teacher
Background —
(Back
to Activity)
What is happening to the tulip bulb during the time it is underground? As you read about the different stages in the tulip bulb life-cycle, consider the ways the tulip has adapted for survival.
Fall
- Winter
Each
fall, we plant spring-flowering bulbs that are in their dormant (resting)
stage. When the underground temperature drops below about 50 degrees
F, the dormant bulb "awakens " and begins to form roots. You can see this if you dig a bulb during this period.
The cold temperatures also trigger changes in cells so it will be energized to send up leaves and flower
buds in the spring. A period
of 6 -9 weeks of temperatures below 50 degrees is necessary for
the plant to grow and bloom. (In warmer climates, people artificially simulate
winter by keeping bulbs in the refrigerator or another cool place for
6 - 9 weeks. Cold treatments can also "force" bulbs to
bloom indoors. (See Hurrying
Spring.)
Spring:
Spring's warmth and rains trigger the tulip bulb to begin to grow rapidly, pushing
up the shoots, leaves, and flower buds. Finally, the bud bursts into bloom.
Late
Spring - Summer:
Late spring and summer are an important time in the life of a tulip plant. The beautiful flower is gone but the leaves continue to grow and
make food for the plant to store. New bulblets form next to the original bulb
and start to grow.
In late summer, the leaves die back, the roots dry up, and the food is stored in the dormant (resting) bulb and bulblets. In the fall, the cycle begins again.
Making
New Bulbs: A bulb propagates itself asexually by growing small bulblets attached to the original bulb. It can take a year or more before bulblets are big enough to produce blooms. Because these grow right from the parent plant, they produce the exact same flower type and color.
Bulbs also produce seed, but they can take up to six years to produce a flower this way — and the new plant isn't likely to look like the parent. Plant breeders often cross-pollinate two types of bulbs to produce seeds of a brand new variety.
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