preserving flowers

Margaret A. Kuchenreuther kuchenma at CAA.MRS.UMN.EDU
Tue Jul 9 13:36:58 EST 1996

>> Dear plant-edders,
>>   I have just been asked how to preserve leaves ith their colors, and it
>> occurred to me it would also be very useful to me to preserve summer
>> flowers with their shapes and colors to use for teaching off-season.  I
>> know about the method where the flowers are put in a bed of sand and all
>> the air spaces filled with sand.  These are then baked to dry them.  But,
>> how long and at what temperature?  Do these then keep in ambient
>> conditions, or must they be sealed so they cannot absorb moisture on damp
>> days?  Will this method work just as well with leaves?
>>   Thanks for any help.
>> Janice
>> ***********************************
>>  Janice M. Glime, Professor
>>  Department of Biological Sciences
>>  Michigan Technological University
>>  Houghton, MI 49931-1295
>>  jmglime at
>>  906-487-2546
>>  FAX 906-487-3167
>> ***********************************

Dear Janice and others,

Here in the frozen North our fall term doesn't start until the third week in 
September, usually after we've had our first hard frost. This leaves little but 
grasses and a few hardy composites for my students to look at as fresh material 
in my plant systematics course, so I routinely, and quite successfully, use 
frozen flowers. I have found that the following steps give me good results:

1)  Collect flowers in the morning when they are freshest and the day is still 
cool.  Collect flowers only, not vegetative plant parts.  (If individual flowers
are tiny, e.g. *Galium*, I collect whole inlforescences.)

2)  Place flowers into a sandwich-sized ziplock bag along with a folded paper 
towel to absorb any moisture (prevents frost accumulation around the flowers 
which sticks them together so). I put about 1.5 times as many flowers into one 
bag as I have students in a section so students who have trouble with their 
first flower can have another.  Therefore, multiple bags of a given species for 
multiple sections.  I also include a paper label in the bag noting the plant 
family and species.

3)  For large and relatively fragile flowers, like wild roses, I put fewer 
flowers in a bag and position the flowers so that that are flattened open.

4)  Keep the bags in a cooler as you collect.  Transfer the bags to boxes 
(labelled by family, subclass,etc.) in a freezer for storage.  

5)  At classtime I transfer the species we'll be using as "unknowns" to the 
freezer compartment of a refrigerator in the classroom.  I remove the labels and
replace them with numbers.  Students come to the freezer to get the flowers as 
they are ready for them.

6)  Because taxonomic keys require information about inflorescence type and 
vegetative characters I have made sets of herbarium sheets of whole plants to 
accompany the frozen flowers I use.  These are labelled with all of the 
pertinent information except family, genus and species.  I have enough so that 
each pair of students can have a sheet to work from as they key out the frozen 

Each summer I preserve about 50 species using this method, and while I wish I 
didn't have to rely so heavily on pressed and frozen specimens, because they are
not as exciting or aesthetically pleasing as living plants, my students find the
materials I give them quite easy to work with.  The only flowers for which I do 
not use this technique are extremely fragile ones like those from some deciduous
trees (e.g. male flowers of *Acer*).

Margaret A. Kuchenreuther
Assistant Professor of Biology
Division of Science and Mathematics
University of Minnesota - Morris
Morris, MN  56267

Phone: (320) 589-6335 or -6300 (message)
FAX:  (320) 589-6371
email:  kuchenma at 

More information about the Plant-ed mailing list