Plant of the Week
Garden Mum
Latin: Chrysanthemum morifolium
The Latin binomial system for naming the stuff of nature was developed in the
1730's by Linnaeus, the famous Swedish botanist. While gardeners have decried
Latin names from the beginning, his elegant system has created a logical way of
classifying and then naming new plants.
But after almost 300 years, you would think the need to tinker with the
arrangement would have been resolved. Not so, as the story of the lowly garden
mum, Chrysanthemum morifolium, shows.
Fall blooming garden mums have come a long way since their introduction from
China in the middle of the 18th century. Breeders have transformed a
perfectly respectable plant with grace and beauty into a compact, multi-colored
anthill that has the cookie cutter characteristics they so love.
But, that’s another story. Here, let us look at the mischief the boys in the
back rooms have been doing as they changed the name from Chrysanthemum to
Dendranthema and now back to Chrysanthemum.
The rules for plant naming are written down and relatively straight forward,
but, as with any language, there is always room for interpretation. All genera
are classified around what is called the "type species," usually the first
species in the genus to be recognized.
In 1961, Nikolai Tzvelev, a Russian taxonomist, concluded that the type
species for the genus Chrysanthemum, C. coronarium and the
ancestor of the garden mum, C. indicum, were not closely related enough
to be combined in one genus. So, because C. indicum was not the first
born son, it had to go to live in a new home he called Dendranthema.
This name change was slow to leak out of the old Soviet empire, being
obscured by the climate of the Cold War and the normally glacial rate of change
in taxonomic circles. It was not accepted by taxonomists until the late 1980s
with gardeners finally receiving word of the decision in 1989. The Europeans were the first to accept the new name, but in
the spirit of the new global village in which we now live, Americans pretty much
ignored it.
Latin name changes may seem trivial when compared to the important things in
life like paying the bills and giving the dog a bath, but they do cause
problems. For one thing, all of your plant reference library is instantly out of
date.
The current taxonomic bible used in gardening circles is Griffiths’ Index
to Garden Plants that appeared in 1994. It adopted the new name while my old
stalwart Hortus III, which appeared in 1976, was stuck with the old
terminology.
Hundreds of nursery firms that publish catalogs had to decide what to call
the plant with a new name. As the word got out about the renaming, there was
significant grousing, but people began to slowly adopt the new name.
But an English botanist had a suggestion for solving the problem; change the
type species for the genus Chrysanthemum to C. indicum, thus force
C. cornarium to leave for a new home.
In 1995, this was proposed to the Committee on Spermatophyta, a learned group
of botanists appointed by the International Botanical Congress, whose sole
mission is to adjudicate such weighty issues. In a very democratic process, the
committee voted 9 to 3 in favor of changing the type species to C. indicum,
thus giving our garden mum back its name.
By bowing to popular demand and reason, they also abandoned a fairly basic
rule of nomenclature that made the new book obsolete while my old book regained
its place of prominence on the bookshelf.
Garden mums are available in a variety of colors from nurseries and mass
merchants. They will continue to open blooms for three to four weeks, or until
stopped by a hard frost.
Most people seem to be using mums on the patio as container plants, not
transplanting them into the garden. The portion of a garden mum that survives
over winter is usually an underground rhizome.
Modern production systems grow mums so fast they never have a chance for the
rhizome to form, so if the winter is hard, many mums will freeze out. For this
reason, nurserymen prefer calling them "garden mums," not the once popular
"hardy mum."
By: Gerald Klingaman, retired
Extension Horticulturist
- Ornamentals
Extension News -
September 19, 2003
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