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  Missing Raphides
From: Ted.Held at hstna.com on 2001.07.05 at 21:48:54(6961)
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
raphides.

ted.held@hstna.com

From: Ted.Held at hstna.com on 2001.07.22 at 08:01:17(7076)
Maybe I should re-cast this query. Has anybody on this list ever seen a
raphide? If so, how? Perhaps they are mythological.

Ted

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From: Durightmm at aol.com on 2001.07.22 at 15:34:24(7085)

Have you ever seen a BROMELIAD regelia   (Neoregelia)  J

From: "Julius Boos" ju-bo at email.msn.com> on 2001.07.22 at 15:34:35(7086)
>>Maybe I should re-cast this query. Has anybody on this list ever seen a
raphide? If so, how? Perhaps they are mythological.

Ted<<

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From: "Deni Bown" deni at yaxhampark.co.uk> on 2001.07.23 at 06:39:18(7091)
Ted,

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 tissues
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. What
exactly would you like me to ask him?

Deni Bown

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From: Ted.Held at hstna.com on 2001.07.23 at 11:11:44(7093)
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?

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From: "Don Burns"donburns at macconnect.com> on 2001.07.23 at 11:42:45(7094)
>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?

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From: StellrJ at aol.com on 2001.07.23 at 19:48:23(7099)
In a message dated Mon, 23 Jul 2001 2:43:13 PM Eastern Daylight Time, "Don Burns" writes:

>
> > The plant juices that I have come in contact with are from freshly cut material,
> not dried. This might suggest to you that drying your material is destroying
> the raphides??

Ah! The experiments of the late Euell Gibbons! Having read reports to the effect that Native Americans ate the tuberous root of Arisaema triphylla, he tested the possibility. Like many aroids, this plant is painfully irritant to the mucous membranes when raw. Gibbons found that no amount of boiling was effective, the root remaining painfully irritant; but, having sliced the roots thinly and drying them six months in the attic, he found they were, indeed, edible after such a treatment. He later had the same results with Symplocos foetidus.

Jason Hernandez

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