epidermal preps

Barry Meatyard B.T.Meatyard at warwick.ac.uk
Thu Jan 27 07:12:04 EST 2000


Dear Plant-Edders,
Re: Doug Jensen's enquiry:
>
>    Next semester I plan to have my botany students investigate the
>anatomy of an assigned plant.  As part of that, I'd like them to look at
>the patterns of epidermal cells and stomata.  My references (old plant
>microtechnique books), say that very few plants give good epidermal
>peels, and they suggest boiling leaves to loosen the epidermis.  I'm
>afraid this will make everything that's not highly lignified or succlent
>into cooked spinach, and I doubt I can get a peel from that.
>    I hope that someone on this list has a method that most students can
>learn in a short period of time, requires few (none is better) dangerous
>chemicals, is not too time consuming, and can be used on a wide variety
>of plants.  I'm not worried about making permanent slides.  Also, I
>don't mind fixing things myself, but would prefer it to be a short
>process.
>
>Doug


My two favourites are Kniphofia (red hot poker) (Liliaceae) and Bergenia
(Elephant's Ears) (Saxifragaceae).

These are both extremely easy to get direct epidermal peels off the leaves
- Kniphofia in particular - where you can strip huge areas off and hardly
touch the mesophyll. Bergenia isn't quite so relaxed about shedding its
skin, but usually a field or two of the HP of the microscope is all one
needs for most things. In any case a few mesophyll cells hanging around
gives a good 3-D impression of the anatomy of a leaf under lower powers.
The technique is to 'snap' the leaf back on itself to produce a broken
edge, which usually then shows a colourless bit of membrane which is the
epidermis. Judicial gripping of this with blunt forceps and careful peeling
is usual sufficient to coax more of the epidermis away from the underlying
tissue. In Kniphofia eventually you get a piece which you can get hold of
with you fingers and strip the whole leaf if you need it!

A comparison between them is interesting - Kniphofia has its stomata is
seried rows - as one would expect in a monocot, and all the stomates are
orientated in the same plane. Bergenia has the stomata orientated more
randomly and the distribution is more even i.e not in rows - I hesitate to
use the word random because I doubt the pattern is this. I've used
Kniphofia in the past with quite young pupils in schools to demonstrate
stomatal opening and closing by manipulating the sucrose concentration of
the bathing solution. It is easy to see whether stomata are open or closed.

Happy peeling!

Barry

Dr.Barry Meatyard
Science and Plants for Schools
Environmental Sciences Research and Education Unit
Warwick Institute of Education
University of Warwick
Coventry
CV4 7AL
UK

Email: barry.meatyard at warwick.ac.uk
Tel: 44 (0) 2476 524228
Fax: 44 (0) 2476 523237

SAPS is at http://www-saps.plantsci.cam.ac.uk


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