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RE: Missing Raphides

  • Subject: RE: Missing Raphides
  • From: Ted.Held@hstna.com
  • Date: Mon, 23 Jul 2001 13:11:44 -0500 (CDT)

I would guess that he would have had to dry his sample before running any
electron microscope picture. I just thought that seeing raphides under any
type of microscope would be a simple matter. Now, my sample came from a
stem. Maybe they only exist in leaf tissue? From the descriptions, it would
seem like they must surely have hard skins or casings if not mineralized
shells. If the outer parts are soft and perishable, would they not be
useless at causing lacerations and penetrations? And the size should be big
enough to see with a simple hand lens. I would expect them to be rather
numerous and easy to get from a radical stem cutting.

Maybe raphides are not characteristic of all dumbcanes. Maybe not all
dumbcanes are hazardous to gardeners or small children?

I had hoped that raphides would have hard, perhaps complex surface
structures, akin to diatoms. An electron microscope picture might be quite
beautiful. Maybe different species would have different types of raphides
and that raphide morphology might be useful for species determinations.
Just some thoughts. I am only an amateur here.

Is there an easy way to get copies of back articles in Aroideana as Julius
Boos helpfully suggested?

I will do a microtome slice of my specimen as Matyas suggested and report
back. I thought that the raphides should have been released with the sap,
however. But maybe you have to masticate the flesh to encounter them.


aroid-l@mobot.org on 07/23/2001 09:39:20 AM

Please respond to aroid-l@mobot.org

To:   Multiple recipients of list AROID-L <aroid-l@mobot.org>
Subject:  RE: Missing Raphides


The photos of the Dieffenbachia raphides were taken as a favor by a medical
scientist friend at the University of Calgary using (if I remember
correctly) a scanning electron microscope and fresh (not dried) leaf
from a houseplant in his office. It's a long time ago now and I doubt very
much if he would remember but I could try to find out more if you like.
exactly would you like me to ask him?

Deni Bown

-----Original Message-----
From: aroid-l@mobot.org [mailto:aroid-l@mobot.org]On Behalf Of Julius
Sent: 22 July 2001 23:35
To: Multiple recipients of list AROID-L
Subject: Re: Missing Raphides

-----Original Message-----
From: Ted.Held@hstna.com <Ted.Held@hstna.com>
To: Multiple recipients of list AROID-L <aroid-l@mobot.org>
Date: Sunday, July 22, 2001 11:01 AM
Subject: Re: Missing Raphides

>>Maybe I should re-cast this query. Has anybody on this list ever seen a
raphide? If so, how? Perhaps they are mythological.


Dear Ted,

I can understand your frustration---maybe the Dieffenbachia that you used
was a hybrid with less 'potency'---you may want to check out the following
two articles in back issues of Aroideana, both show photos of these

a) "The remarkable shooting Idioblasts" by Father Eugene Middendorf, Bio.
Sciences Dept., Quincy College, Quincy,  Ill. 62301 in Aroideana Vol.6, No.
1.    I believe that Deni Bown`s illus. were done based on the photos in
this article, which also gives directions on how to obtain and view this
mech. microscopically.

b) "A possible defence mechanism in Scindapsis latifolius (Araceae:
Monsteroideae)" in Aroideana Vol. 16--- I could not find my copy of Vol.
so can not give any further details on this article, but remember that it
had a photo of the raphides as they were 'shot' out of the plant while it
was being prepared as a herb. specimen sheet.

Good luck.


Julius Boos

aroid-l@mobot.org on 07/06/2001 12:48:55 AM

Please respond to aroid-l@mobot.org

To:   Multiple recipients of list AROID-L <aroid-l@mobot.org>
Subject:  Missing Raphides

I read Deni Bown's chapter "Acids and Crystals" with rapt attention
[Aroids, 2nd Edition, Deni Bown, Timber Press, 2000]. I saw the
illustration of dumbcane raphides on page 279 and resolved to photograph
them with a scanning electron microscope. I had a handy dumbcane (looks
like the variety of D. seguine labelled "Candida" in Plate 40 from that
book) and I cut a stem and caught some of the sap from the wound. When the
sap was dry I looked at it under the electron microscope. There are
numerous polygonal structures (crystals?) about 1 micron in size. But these
are blunt, not at all like the sharp needles I had hoped to see. I found no
evidence of anything like the raphides described in the book. She says
raphides should be about 150 to 300 microns in length and 8 to 15 microns
in diameter. So I have plenty of resolution to see something that size.
Does anyone know what I did wrong?

If you wish to see the picture I made of the dried dumbcane juice you can
contact me directly. I will e-mail you the picture. The file is about 1.25
megs and is in black and white. It is of interest even if there are no


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