Messenger - Vol. 2, No. 3, Page 12
Summer 1993
On Research
Native perennials become candidates for cloning

     Sherry Kitto's perennial garden grows in rows of baby food jars in
Worrilow Hall on the Newark campus. Working with unique plants native to
the Northeast, this University of Delaware plant tissue culturist is
developing the procedures necessary to clone the perfect foamflower, or
birdfoot violet.
     The procedures, or "clonal protocols," provide information on the
ideal medium, nutrients and combination of growth regulators (plant
hormones) necessary for a particular plant. Once set, the procedures are
published, making them available to commercial greenhouses and avid amateur
     Tissue culture propagation allows Kitto to take a slice from a bud of
an attractive plant, place one- centimeter-size bits into a medium that
includes growth hormones and produce hundreds of miniature shoots in jars.
Several weeks later, the shoots can then be dipped in a rooting hormone and
transferred to a greenhouse.
     "With tissue culture, you can get 10 times the number of plants you
started with within four weeks," says Kitto. "Once a system is worked out,
you can produce 1 million plants from one shoot in six months. That doesn't
happen in nature."
     After she has worked out the clonal protocols for proliferating
shoots, for generating roots and for acclimating a particular plant, she
must then decide whether these plants perform as well as regular seedlings
in a garden. Kitto does this by placing the plants in nurseries and in
individual gardens and following them over time. "Fortunately, plants
produced from tissue culture are frequently more vigorous than seedlings
found in nature," she says.
     Kitto selects the plants she will propagate based on their aesthetic
quality, whether flower color or a leaf with an attractive shape or shade.
"It has to be a plant that is not available in the nurseries," she says,
"but it must be one that the general public will ultimately want."
     So, she talks to "plant-a-holics or people who will go to extremes to
cultivate certain plants," asking them why certain plants are unique and
how easy they are to grow. "When you talk to these people, you find there
are features they generally like, such as deeply lobed or shiny leaves, a
particular color in the heart of the flower or a new shape."
     Over the last nine years, she has cultivated three native perennials
that she thinks are of interest to this audience: Oakleaf tiarella or
foamflower, a new cultivar developed in her laboratory, which has a nice
leaf shape and takes on an attractive color in the fall; Allegheny
pachysandra, which grows a little higher and larger than the common variety
and also has tinted fall foliage; and spigelia, which grows 18 to 20 inches
high and produces a bright red, tubular flower with a yellowish interior
all summer long.
     "I try to make my system of propagation refined enough that a
commercial tissue culture business or wholesale nursery can readily use
it," she says. "If the tissue culture system I develop is not economically
feasible, I find out right away."
                                   -Cornelia Weil