Most published plant labs are considered "cookbook" but most can be
"un-cooked" and converted to inquiry-based.
Un-cooking the Lab: A Guide to Constructing Inquiry-based Labs in
One way to keep student experiments fresh is to use different plants,
such as houseplants, chia, weeds, garden flowers and native
wildflowers, instead of the usual suspects such as corn, bean, tomato,
sunflower, fast plant, Arabidopsis, etc. If students use a nonstandard
species, they can obtain original data on nutrient deficiency symptoms,
stomatal density, leaf starch, hormone responses, light requirements
for seed germination, salinity tolerance, gravitropism, phototropism,
etc. Houseplants and garden flowers from seed grow rapidly under fast
plant fluorescent light banks or growbuckets that run 24 hours per day.
Some inquiry-based student labs could involve the following questions:
1. A plant breeder has an albino corn cultivar he wants to use in
breeding. However, it dies well before flowering because it lacks
chlorophyll. Find a simple way to grow albino corn seedlings to
2. Your mother wants to know if cheap home remedies such as Sprite, a
penny or sugar can be used instead of commercial cut flower
preservatives such as Floralife.
3. A houseplant grower noticed that adventitious plantlet formation on
devil's backbone (Kalanchoe daigremontianum) leaves does not occur
during the summer. The grower uses adventitious plantlets for
propagation. Find a simple way to promote plantlet formation.
4. A student used Miracle-Gro fertilizer to make a hydroponic nutrient
solution for their science fair project. The plants in hydroponics
died. Why? Make a hydroponic solution from Miracle-Gro or another
readily available houseplant fertilizer suitable for plant growth using
chemicals from a garden center or drugstore.
5. A grower used sphagnum peat moss to root cuttings but they rooted
poorly. Why? Determine if sphagnum peat moss can be modified to make it
a satisfactory medium for rooting cuttings.
6. An artist wants to attach a room of furniture to a ceiling or wall
and include potted houseplants that will appear to grow normally in the
inverted positions. How can the artist counteract gravitropism for his
7. How does an excess of boron affect plant growth?
8. How much force does seed imbibition produce?
9. How does polarity affect adventitious root formation in willow stem
10. How do plants respond to iron deficiency? (When deprived of an iron
chelate in solution culture, piggyback plant (Tolmiea menziesii)
remains iron deficient even if the roots are coated with iron oxide. In
the same situation, many other species lower the pH and are able to
make the iron in the iron oxide available)
11. Does apical dominance control sprouting in potato tubers?
12. Does salinity tolerance vary among plant species?
13. Does the carbon dioxide compensation point differ between C-3 and
14. How do chemical growth retardants affect plant growth?
15. Do commercial plant leaf shines affect houseplant growth?
16. How does ammonium/nitrate ratio affect rootzone pH and plant
American Biology Teacher and Journal of Biological Education are
probably the two main journals with ideas for inquiry-based plant labs,
athough ABT has had fewer plant articles the last few years.
The AskEric database can be used to locate many plant teaching
I have a collection of several dozen plant physiology lab manuals from
the late 1800s onward. They contain cookbook labs but many could be
adapted to inquiry-based labs. There have not been too plant physiology
lab manuals published lately. The American Society of Plant Physiology
lists several on its webpage "Teaching a Plant Physiology Laboratory
Course for the First Time?" by Carol Reiss:
Fast plants and C-fern have some interesting ideas for student labs.
Here's a few other web sources of inquiry-based plant labs:
Experiments and Projects with Duckweed
Stomata: Microscopic Openings That Let Plants "Breathe"
Example of an Inquiry-Based Laboratory Exercise on Duckweeds
Investigating the induction of the CAM photosynthetic pathway in
Mesembryanthemum crystallinum , an inquiry-based laboratory
Teachers sometimes design some labs around particular pieces of
equipment they have available or their research interests.
When I was in grad school, an inquiry-based student project asked what
was the cause of early spring leaf injury on a landscape shrub.
Students were provided with thermocouples, a floodlight and an aquarium
tank. It was up to students to design and set up the experiment to
detemine if the leaf injury was due to high light or high temperature.
Another student project required in an introductory horticulture course
was for students to care for a plant in their home and write a report
on how they cared for it and how it grew. It required them to collect
data, observe and describe.
There is a lot of potential for having college students do research on
the best plant teaching techniques. William Ganong did this in the
early 1900s as discussed in a 23 Feb 2005 post.
You mentioned that the labs would be "essay-based." Some students might
want to tackle more practical projects such as putting together a
guided tour of campus trees, shrubs and plants. It would involve
identifiying plants and could include basic botanical info, ethnobotany
and natural history. That kind of project could result in a useful
brochure or website.
Another worthwhile activity is to devote one lab period to a campus
field trip to observe botanical concepts discussed in the course such
as negative phototropism of English ivy stem tips, juvenility and
maturity in English ivy, stem grafting in English ivy, heaving of
sidewalks by tree roots, grafted trees, growth of moss in sidewalk
cracks illustrating their desiccation tolerance and their "pioneer
plant" ability, etc. There are also many worthwhile botanical,
ethnobotanical and natural history for campus trees. Campuses often
have many interesting plants such as ginkgo (living fossil, dioecious,
fleshy seed coats, dichotomous leaf venation, herbal remedy, only
living species in its phylum) and dawn redwood (living fossil,
deciduous conifer, only discovered in the 1940s).
David R. Hershey