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Base or
primary leaf color is defined as the color that occupies at
least 60% of the surface area of the plant. Secondary colors,
usually involved with variegation, are those colors that occupy
40% or less of the surface area.
Variegation occurs on a plant
when chlorophyll is either in a very low level or is missing
entirely in a part of the plant tissue. When this occurs, the
tissue will reflect either the yellow underlying color or the
complete absence of pigment resulting in white color.
This color difference may appear
in three locations on the leaf including leaf margins
(Marginal), middle leaf (Medial) and variable pattern (Streaked
or Splash).
Depending on the relative amounts
or lack of chlorophyll or carotene (yellow) or other pigments,
the color of the variegations according to The American Hosta Society would include:
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Greenish White
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Creamy White
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Pure White
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Green Speckling
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White Speckling
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Streaked with colors
1-5
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Mottled with colors
1-5
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Perhaps the most common type of
variegation in hostas occurs along the outside edge or margin of
the leaf. There are hundreds and hundreds of hostas with
either
a white or yellow margin. The width of the margin may range from
a very thin, almost undefined line to a very wide, dominating
margin that covers up to 40% of the leaf surface.
As mentioned in the previous discussion of the
layers of a hosta leaf, changes in the pigment cells i.e. plastids,
in the L1 layer will often result in a change in color of the leaf
margin.
When it comes to marginally variegated hostas,
it appears that most people generally prefer those with wide, yellow
margins to those with narrow, white edges.
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Sometimes that layer of cells
that runs down the center of the leaf is the one that loses its
chlorophyll. Center variegation can vary in width from a sliver
to a wide strip dominating the leaf blade and covering up to 40%
of the surface. As mentioned in a previous section, there may be
so much white that it
covers
60% and becomes the base color.
In this situation, there is usually a change in
the plastids of the L2 layer of the leaf.
Medially variegated hostas seem to be more
popular with gardeners than those with marginal variegation.
Unfortunately, some hostas with medial variegation are challenges to
keep healthy and showy in the home garden. Those with very wide,
white variegation are missing a lot of the green chlorophyll
molecules. This results in leaves that have thin, tissue-like
substance which is loved by slugs and easily scorched by too much
sunlight in hot, dry summers. Also, lacking chlorophyll means the
plant does not have the ability to grow as vigorously as its all
green counterpart.
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Streaked and splashed are the
most often used terms to describe this color pattern but you
might also hear stippled, flecked, marbled and misted used at
times. This is the least common but, perhaps, the most
intriguing form of hosta variegation.
Streaking occurs when random cells in the leaf
lose their chlorophyll. The plastid cells that contain the color
pigments have the ability to move between layers in the leaf which
results in this random pattern of variegation. This is the least
stable form of variegation and in many cases, the plastids will
migrate toward the margins or into the center where they stabilize.
The plant is then, of course, considered to be marginally or
medially variegated. Or, plants may totally revert back to the
original base color resulting in a green, blue-green or yellow
plant. Several streaked cultivars such as H. 'Spilt Milk' or H. 'Sea
Prize' will stabilize and stay streaked indefinitely.
When streaked forms of certain plants show up,
they often sell for very high prices. Why? Because they are very
valuable for use in hybridizing new hostas. More on that later.
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