the practive of cutting into the base of a bulb to stimulate adventitious bulblet formation on the base of scales two types: scooping and scoring used for bulbs that have slow natural increase (hyacinth)

a miniature bulb forms in the axil of a bulb scale provides a method of vegetative propagation

the clusters of buds at the nodes of the potato tuber

the rhizome growth type intermediate between the two forms: leptomorphs and pachymorphs

Geophytes & Other Specialized Structures Flashcards by Sarah Holton

Back Bulbs

the pseudobulbs that do not have foliage
an old pseudobulb from which the leaves have dehisced

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Basal Cuttage

the practive of cutting into the base of a bulb to stimulate adventitious bulblet formation on the base of scales
two types: scooping and scoring
used for bulbs that have slow natural increase (hyacinth)

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Basal Plate

the short thickened stem of a bulb
modified stem

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Bulb

a specialized underground organ
consists of:
- modified stem: basal plate (a shot, fleshy, stem axis)
- a growing point or flower primordium at the apex of the basal plate
- enclosed by thick fleshy scales (the leaf base that contains stored food)
types:

Tunicate/Laminate (papery covering)
1. Type 1 (leaf scales. Tulip)
2. Types 2 (swollen leaf bases. Amaryllis)
3. Type 3 (both leaf scales and swollen leaf bases. Daffodil & Iris)
nontunicate (no papery covering. ex: Lily)

can be propagated by:
- natural offsets - most common
- seed propagation
- aerial bulbils
- stem cuttings (some lilies)
- scaling in non-tunicate bulbs
- leaf cuttings (grape hyacinth, blood lily)
- basal plate cottage - scooping, scoring
- bulb cuttings - chipping, twin-scaling
- micropropagation

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Bulb Chipping

also called bulb cutting, fractional scale-stem cottage
a method of propagation in which a bulb is cut into gragments of 3 or 4 bulb scales attached at the basal plate

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Bulblets

a miniature bulb
forms in the axil of a bulb scale
provides a method of vegetative propagation

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Bulbil

a type of bulblet
produced in the aerial portion of the plant
enclosed within a dry, membranous scale

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Contractile Roots

the thickened, fleshy roots
that pull the bulb to a deeper layer in the soil
by shrinking and expanding
don’t function very well for nutrient uptake (thats what fiberous roots do)
not all bulbs produce contractile roots
- lilies have them

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Corm

a unique geophyte structure
in which the base of the stem axis is:
- swollen,
- has nodes and internodes,
- and is enclosed in a dry membranous tunic
is a solid piece of stem
apex of corm is terminal shoot that will develop into leaves and the flowering shoot
polar
mostly storage tissue composed of parenchyma cells
generally have fibruous roots (for nutrient and water uptake) and contractile roots (to get corms to proper depth)
new corms often form ontop of old corms (which disintergrate) with new cormels forming at base
- sometimes new corms just stack up on old corms, which persist
- sometimes new corms are produced on stolons (produced laterally form the base)
can be propagated by:
- natural cormel offets - most common
- seed propagation
- division of large corms
- micropropagation

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Cormels

a miniature corm produced on a short stolon from the base of the corm
they develop between the old and new corms

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Droppers

a special kind of bulblike structure
occuring in tulips
which grows to a deeper level to produce a new bulb
a stolon that forms a bulb at its tip
another mechanism to move the bulb down to its proper depth

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Eyes

the clusters of buds at the nodes of the potato tuber

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Geophytes

types of plants that survive part of their annual life cycle as a dormant, fleshy, underground structure
2 principle climatic cycles for which geophytes are adapted:

the warm-cold cycle of temperate zones
the wet-dry cycle of tropical and subtropical zones

functions:

aids in survival in adverse conditions as storage of food, nutrients, and water
allow clonal regeneration of species (so often reproduce both sexually and asexually)

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Leptomorph

types of rhizome growth
that exhibits indeterminate growth
slender with long internodes
- not as fleshy (more stolon like)
lateral buds at each node may remain dormant or produce new shoots
can continue to develop new plants at each node
will spread far and wide - does not form clumps

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Mesomorph

the rhizome growth type
intermediate between the two forms: leptomorphs and pachymorphs

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Mother Bulb

the flower-producing bulb
made up of the basal plate, fleshy scales, and the flowering axis
prior to flowering, a new daughter bulb(s) is developing within the mother bulb
a cluster of bulbs still attached at the basal plate

Nontunicate Bulb

also called scaly bulbs
type of bulb
does NOT have the papery covering
has seperate ‘scales’ attached at the basal plate
are easily damaged and prone to drying
Lily

Offsets

a latent shoot
develops from the base of the main stem in certain plants
- such as an offset bulblet that is produced from a larger mother bulb
bulbs naturally multiply by producing offset bulbs
daughter bulbs still attached to the main bulb

Pachymorph

a type of rhizome growth
that exhibits determinate type of growth
are larger
little more storage
slow growing
each season’s growth terminates with a flowering bud
can see last season’s terminal shoot - scar
vegetative growth continues at the lateral bud
forms clumps

Pseudobulbs

an enlarged, special storage structure produced by many orchid species
consisting of an enlarged, fleshy section of the stem made up of several nodes
assist plants to survive during dry periods
can be either:
- back bulb - it is leafless
- green bulb - has leaves
- they only differ by age
can be propagated by:
- seed division
- division - common
- back or green bulb cuttings
- micropropagation

Rhizome

a horizontally growing stem of specific plant species at, or near, the surface of the ground
modified shoot tissue
- growing at or near the surface
- fuctions as sotrage tissues (where as stolons done)
mostly in monocots
is two types:
- pachymorphs
- leptomorphs
can be propagated by:
- seed propagation
- division of rhizome sections - common
- micropropagation - few

Scales

also called bulb scales or leaf scales
the expanded fleshy leaf base of a bulb that contains stored food
modified leaf
for nutrient, water sotrage

Scaling

.a propagation procedure in which individual scales are removed from the mother bulb and placed under appropriate conditions to cause the formation of adventitious bulblets
usually 3 to 5 bulblets will develop from each scale
on lily species
is done soon after flowering in midsummer, although it might be done in late fall or even midwinter

Scooping

a type of basal cuttage
carried out by cutting away the basal plant with a special scoop-like device
need to destroy the apical meristem
adventitious bulblets develop from the base of the exposed bulb scales

Scoring

* a type of basal cuttage * carried out by cutting at right angles across the base of the bulb * cuts need to be deep enough to destroy the apical meristem * growing points in the axils of the bulb scales grow into bulblets

Tuber

* a swollen modified stem with: * nodes and internodes * functions as: * storage structure * an organ of vegetative propagation * underground * can be propagated by: * division of the tuber - needs to include bud * seed propagation * aerial tubercles * stem cuttings * micropropagation

Tubercle

* the small aerial tubers produced in leaf axils of certain plant species * usually produced in short days * appear on plants in late summer * are easily removed from the plant * can be dried and stored overwinter for spring planting

Tuberous Root

* an enlarged fleshy root (modified root) * as a storage organ * are polar (shoots at one end and roots at the other) * example: sweet potato, carrots * tuberous roots are modified root tissue, while tubers are modified stem * can be propagated by: * seed propagation - common * division of crown w/ tuberous roots attached - common * stem cuttings - common for sweet potato * micropropagation

Tuberous Stem

* the swollen stem structure * produced by enlargement of the hypocotyl * ex: cyclamen, tuberous begonia * have a vertical orientation * one or more vegetative buds produced on the upper end of the crown (at the surface) * can be perennial * can be propagated by: * seed propagation - common * division

Tunicate Bulb

* also called Laminate * type of bulb * outer layer of bulb scale are dry and papery * provides protection from drying & mechanical injury (doesnt bruise as easy) * inner fleshy scales are continious, concentric * gives bulb solid feel * 3 types: 1. Type 1 * leaf scales * scales arise from the basal plate * foilage leaves arise from flowering stem * Tulip 2. Type 2 * leaves with swollen bases * arise from basal plate and inflorescence * Amaryllis 3. Type 3 * both leaf scales and swollen leaf bases * Daffodil & Iris

Twin Scaling

* a variation of bulb cutting * using a segment of two scales with a portion of the basal plate * important in propagation of Narcissus

Vernalization

* the biological process in which flower primordia are induced by exposure to a period of chilling