Bulb Information
The term "bulb"
is used by most people to refer to plants that have underground, fleshy
storage structures. Only some of the plants commonly called bulbs actually
are bulbs. The definition of a bulb is any plant that stores its complete
life cycle in an underground storage structure.
The primary function of these underground storage structures is to
store nutrient reserves to ensure the plants' survival.
Bulbs or bulb-like plants are usually perennials. They have a period
of growth and flowering. This is followed by a period of dormancy where
they die back to ground level at the end of each growing season. For
spring bulbs, the end of the growing season is in late spring or early
summer. Spring bulbs start to grow again in the fall and flower the
following growing season.
Bulbs can be broken down into five types of storage structures. These
include: true bulbs, corms, tubers, tuberous roots and rhizomes. A sixth
category of fleshy roots has been added here for the purpose of showing
the structure. Daylilies and peonies, which are popular plants with
gardeners, are examples of this type.
True Bulbs
The true bulb has five major parts. It contains the basal plate (bottom
of bulb from which roots grow), fleshy scales (primary storage tissue),
tunic (skin-like covering that protects the fleshy scales), the shoot
(consisting of developing flower and leaf buds), and lateral buds (develop
into bulblets or offsets).
True bulbs are divided into tunicate bulbs and imbricate bulbs. A tunicate
bulb has a paper-like covering or tunic that protects the scales from
drying and from mechanical injury.
Good examples of tunicate bulbs include: tulips, daffodils, hyacinths,
grape hyacinths (muscari), and alliums.
Many plants such as daffodils form new bulbs around the original bulb.
These bulbs, called offsets, develop from buds within the base of the
mother bulb and produce new plants. When these bulbs become overcrowded,
the flowers start to diminish in size. This is an indication that it
is time to dig up and divide the bulbs.
An example of the imbricate bulb is the lily. The imbricate bulb does
not have the tunic (papery covering) to protect the fleshy scales.
Imbricate bulbs must be kept constantly moist before planting so they
are not injured by the scales drying out.
Lilies can be propagated from bulbils that develop in the leaf axils
of the plant. They can also be propagated from bulblets that develop
at the base of fleshy lily scales if maintained in a moist sand medium.
It will take more than one year for the bulbils or bulblets to become
flower size.
Corms
A corm is a swollen stem base that is modified into a mass of storage
tissue. A corm does not have visible storage rings when cut in half.
This distinguishes it from a true bulb.
The corm contains a basal plate (bottom of bulb from which roots develop),
thin tunic and a growing point. Examples of plants that develop from
corms include gladiolus, crocus, and autumn crocus.
When gladiolus corms are dug in the fall, they should be separated
into well developed corms, to be stored for replanting, and poorly developed
corms that the gardener may want to discard. The newly dug corms will
have cormels that are pea size formed around the top of the old corm.
The remains of the old corm will be directly beneath the newly formed
corms. When the corm is cleaned up and the old stem removed, the growing
point of the corm will be evident. The cormels can be saved and replanted
in the back of the garden until they reach flowering size.
Examples of plants that develop from corms include gladiolus, crocus,
and autumn crocus.
Tubers
A tuber differs from the true bulb and the corm by not having a basal
plant from which roots develop and not having a protective tunic covering.
The caladium tuber has buds scattered over the tuber surface from which
shoots and roots develop.
Examples of plants that develop from tubers include caladiums, oxalis
and anemones, and the common vegetable, the potato. (The potato does
flower.)
Tuberous Roots
The tuberous root differs from other root structures by the nutrient
reserves being stored in an actual root instead of an enlarged stem.
The dahlia reproduces from buds at the top end of the root or base
of the stem.
The tuberous root of a dahlia should not be divided before placing
in storage in the fall but should be divided at planting time. The root
should be divided into sections with an eye bearing portion of the stem
left with each section of the root.
The tuberous-rooted begonia reproduces from buds on top of the round,
flat tuber.
Rhizomes
Rhizomes differ from other storage structures by growing horizontally
under the surface of the soil. On some plants, this type of rooting
structure can be very invasive.
The lily-of-the-valley rhizome spreads horizontally underground and
produces pips which develop into new plants. This plant is increased
in the landscape by digging in the fall and removing pips with developed
roots for replanting.
Fleshy Roots
Plants that have fleshy roots store nutrient reserves in the fleshy
roots.
Both peonies and daylilies can be propagated by dividing. The root
clumps of peonies should be divided in the fall leaving at least three
crown buds with each clump.
The daylily can be divided in the fall or spring into plantlets with
a single fan of leaves.
The daylily has a fleshy root system with some varieties having what
might be considered a rhizome type root system. Daylilies are hardy
herbaceous plants with a perennial growth habit. They have clumps of
rich green, smooth foliage that dies back during the winter.
Source: Bulbs and Other Rooting Structures by Ron Cornwell, University
of Illinois Extension Educator, and Floyd Giles, University of Illinois
Extension Specialist.
Bulb History
Daffodil History & Lore
Daffodils were brought to Britain by the Romans who thought that the
sap from daffodils had healing powers. Actually the sap contains crystals
that can irritate the skin.
Greek mythology gives us the term narcissus. There was a young Greek
named Narcissus. A nymph called Echo was in love with him, but Narcissus
broke off the relationship. Heartbroken she hid in a cave and died.
Later Narcissus, who was very handsome and quite taken with himself,
saw his face in a pool, and as he leaned over to see better, fell in
and drowned and became the flower.
Hyacinth History & Lore
According to GreeK mythology hyacinth got its name when a young boy
named Hyacinth was killed when a discus hit him in the head during a
game. A hyacinth sprang from the cut in his head as he lay in the arms
of the god Apollo, who was wailing in grief. Wild hyacinths have letter-like
patterns on their petals which look like the "A" in Greek
which indicates the sound of wailing.
Hyacinths came to Europe from Turkey. A German doctor named Leonhardt
Rauwolf, collected samples of hyacinths when he visited Turkey in 1573.
By the early 1700s hyacinths were very popular with more than 2,000
cultivars available.
Crocus History & Lore
According to legend the Greek Gods Zeus & Hura loved each other
so passionately that the land where they lived burst open with crocuses.
Crocuses were brought to England from France by Jean Robin, a Director
of Gardens in Paris. Crocuses came to the United States on ships by
settlers who planted them around their cabins.
Information provided by the University of Illinois Extension http://www.urbanext.uiuc.edu
