Understanding Bulb Flowers
 Bulbs are among the most interesting, most beautiful
and easiest to grow of all flower varieties.
Tulip bulbs were once so prized in Holland that it led to one
of the best known financial bubbles in history, and even
today, tulips are a leading export from that part of the
world.
Even though bulbs are not quite so highly prized
today as they were in 17th century Holland, they are still
loved for their scents, their colors and their shapes, and
gardeners love the fact that most bulbs are hardy and easy to
grow.
Many of the most popular varieties of flowers are
actually grown from bulbs,
including tulips, crocuses, daffodils, irises, lilies,
daylilies, dahlias and snowdrops.
One thing
all bulb based plants have in
common is that they grow from structures located under the
ground. These underground structures provide the nutrients and
energy the plants need to grow.
Even though bulb based
plants are collectively known as "bulbs', there are actually
five distinct types of bulb plants — the true
bulb, the corm, the tuber, the rhizome and the tuberous
root. This article will provide examples of each
type.
The True Bulb
The true bulb
is in reality an underground stem base containing an embryonic
plant. The embryonic plant contained within the steam base
already contains the leaves, stems and flower buds, all ready
to burst forth once optimal growing conditions
are provided. This setup allows the plant to lie dormant
during adverse conditions, and thus to survive droughts and other
environmental challenges.
The embryonic plant contained
within the stem base is surrounded by scales (modified leaves
that overlap in a manner reminiscent of reptile or fish
scales). At the bottom of the bulb is a basal plate; this
basal plate holds the scales together and produces the roots
of the plant.
Examples of true bulbs are such
popular flower varieties as daffodils, tulips and
lilies. True bulb varieties of plants are susceptible
to dryness and must be handled carefully. When properly cared
for, however, individual bulbs can live for many years without
being planted.
The Corm
A corm,
like a true bulb, also contains a stem base, but the tissue of
the base is solid, and it lacks the scales seen in true bulbs.
The roots grow from a basal
plate which is located at the bottom of the corm, and the
growth point is located at the top of the corm.
Popular
types of corms include gladiolas and crocus. Each corm
lasts for a single season, and as the corm shrinks
away after blooming, a new corm
forms on top of it. In addition, small increases, called
cormels, are produced around the base of the corm's basal
plate.
The Tuber
Like corm and true
bulbs, a tuber is actually an underground stem base. Unlike
corms and a true bulbs, however, the tuber does not contain a
basal plate. Instead, the roots of the tuber grow from both
the base and from the sides. A tuber will have
multiple growth points spread out over its top
surface.
The Rhizome
The
rhizome is actually a thickened stem that grows either partly
or completely underneath the ground. The largest growth point
on a rhizome is located at one end, and additional growth
points are located along the sides. The most well
known rhizome is the bearded
iris.
Tuberous
Roots
Unlike other types of bulbs, which are
actually specially adapted stems, the tuberous
root is not a true root. Instead, fibrous roots designed to
absorb nutrients and water grow from the sides and the tip of
the tuberous root. Most tuberous roots grow in a cluster, and
swollen tuberous parts radiate out from a centralized point.
The growth points of a tuberous root are found on the bases of
the old stems and not on the roots themselves. Dahlias
and daylilies are the best known examples of tuberous
roots.
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