Definition of Plant

David Hershey dh321 at
Sat Oct 9 00:37:19 EST 1999

I think it's something worth discussing. Most botany textbooks don't
have the term plant in their glossaries. Stern's "Introductory Plant
Biology" does and defines plants simply as members of the Kingdom
Plantae. There is certainly a lot of holdover from the old two kingdom
system where plant was basically defined as nonanimal.  

I think there are advantages to having a clear definition for plant.
Botany is heavy on terminology, and much of it is confused despite
lengthy glossaries in most botany/biology texts, floras, and field
guides not to mention several dictionaries of botany. A lot of the
definitions are imprecise, and different books often have significantly
different definitions for the same term. Even young children should be
able to tell apart a bacterium, a mushroom, and a tree, so to call all
of them plants is potentially confusing especially given how difficult
it is to replace student misconceptions about science with correct
knowledge.  It would be very useful if there was a copyright-free,
official online botanical glossary so that there could be less confusion
in terminology. 

The five kingdom system has wide acceptance in textbooks and although
there are competing schemes, such as the three domain system, the five
kingdom system has a lot of advantages for educational use. Five
Kingdoms is often taught in high school biology and even as early as the
6th grade:  

David Hershey
dh321 at

Russell_Goddard wrote:
> On Thu, 7 Oct 1999, David Hershey wrote:
> > the Plant Kingdom
> > consists of just bryophytes and vascular plants, so I was surprised that
> > the American Society of Plant Physiologists'.. states...
> > that "Plants exhibit diversity in size and shape ranging from single
> > cells to gigantic trees."
> >
> > Is there still disagreement over what organisms are included in the
> > Plant Kingdom?
> >
> My answer?  I don't think there is that much disagreement with what
> organisms are included in the Plant Kingdom, but there is disagreement on
> what organisms might be included under the TERM, "plant."  I tell my
> students that the word plant is a term and not a taxonomic classification.
> This makes it much easier for them to digest the evololutionary origins of
> terrestrial plants.  As a term, many definitions of the word "plant" are
> in use by biologists (and others).  You really have two questions above.
> "What organisms should be included in Kingdom Plantae?"  ...and "what is a
> plant?"  The word "plant" is not necessarily synonymous with organisms in
> Kingdom Plantae.  I spend my first lecture/discussion in botany class on
> this topic, "What is a plant."  There is no clear answer.  I use a broad
> definition that includes all photosynthetic (chlorophyll a containing)
> organisms in three Kingdoms.  I then spend time talking about the
> cyanobacteria in general and prochlorophytes specifically for making
> connections to the eukaryotic algae.  I like to show the diversity of
> form and function in several Phyla of algae and their similarities to
> terrestrial plants, then spend more time on the Chlorophyta as containing
> possible progenitors to what we now include in Kingdom Plantae.  So for
> me, they are all "plants" but obviously this is debatable.  As botanists,
> do we need to define this term more specifically among ourselves?
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> Valdosta State University       Main Office:  (912) 333-5759
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