Re: [IAWA Forum] Re: Radial water transport

From: Guillermo Angeles Alvarez <alvarezg@ecologia.edu.mx>
Subject: Re: [IAWA Forum] Re: Radial water transport
Date: Mon, 07 Oct 2002 11:06:04 -0500
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Hi,
Answering Dr. Tyree regarding unlignified rayparenchyma:
I am currently working with Urera caracasana(a tree) and U. eggersii (a
liana). Both of them present zones of lignified and unlignified
parenchyma. The liana has very wide rays, with alternating zones of
lignified and unlignified parenchyma. This species has a way to secure
tangential water movement across these wide rays, producing vessels
which run almost horizontally, comunicating  areas of vessels to both
sides of the rays. However, we do not have evidence of how this liana
copes with radial water transport through thes exceptionally wide rays.
I made resin-casrtings of Urera stems, but unfortunately, parenchyma
tends to fall appart in individual cells. Only vessels form nice casts.
By the way, I would appreciate refrences on unlignified parenchyma.

Guillermo Angeles
Instituto de Ecología, A.C.
Depto. de Productos Forestales y Conservación de Bosques
Km. 2,5 Carretera Antigua  a Coatepec No. 351
Congregación “El Haya”
91070 Xalapa, Veracruz
México.



MelTyree@aol.com ha escrito:

> But I don't think intercellular spaces could contribute much to radial
> transport of liquid water in trees. The intercellular spaces would
> have to be very well isolated from outside air otherwise they would
> embolize very easily. My guess (and this is only a guess) is that
> intercellular spaces would be water filled only from xylem pressure
> potentials of 0.0 to -0.15MPa.
> The accepted interpretation (without lots of proof) is that
> intercellular spaces are a location of stored water and such stored
> water is mostly gone by -0.2 MPa. But while the spaces are filled with
> water they could contribute to radial transport. See Xylem Structure
> and the Ascent of Sap (Second edition) by Tyree & Zimmermann, which is
> now in print from Springer!
> If you have any photos of intercellular spaces I would be very
> interested in having copies. I think we need more research on this
> topic.
> The story about ray cells NOT being lignified is interesting to me.
> Does anyone have any citations for that?
> Thanks,
> Mel
>
> Melvin T. Tyree
> Project Leader NE4103
> USDA Forest Service
> Aiken Forestry Sciences Lab
> 705 Spear St  PO Box 968
> Burlington VT 05402
> Phone 802 951 6771 x 1310
> FAX 802 951 6368

--
Guillermo Angeles.
Instituto de Ecología, A.C.
Depto. de Productos Forestales y Conservación de Bosques
Km. 2,5 Carretera Antigua  a Coatepec No. 351
Congregación "El Haya"
91070 Xalapa, Veracruz
México

Tel. (228) 842 18 35
Fax  (228) 818 7809


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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
Hi,
<br>Answering Dr. Tyree regarding unlignified rayparenchyma:
<br>I am currently working with Urera caracasana(a tree) and U. eggersii
(a liana). Both of them present zones of lignified and unlignified parenchyma.
The liana has very wide rays, with alternating zones of lignified and unlignified
parenchyma. This species has a way to secure tangential water movement
across these wide rays, producing vessels which run almost horizontally,
comunicating&nbsp; areas of vessels to both sides of the rays. However,
we do not have evidence of how this liana copes with radial water transport
through thes exceptionally wide rays. I made resin-casrtings of Urera stems,
but unfortunately, parenchyma tends to fall appart in individual cells.
Only vessels form nice casts.
<br>By the way, I would appreciate refrences on unlignified parenchyma.
<p>Guillermo Angeles
<br>Instituto de Ecolog&iacute;a, A.C.
<br>Depto. de Productos Forestales y Conservaci&oacute;n de Bosques
<br>Km. 2,5 Carretera Antigua&nbsp; a Coatepec No. 351
<br>Congregaci&oacute;n “El Haya”
<br>91070 Xalapa, Veracruz
<br>M&eacute;xico.
<br>&nbsp;
<br>&nbsp;
<p>MelTyree@aol.com ha escrito:
<blockquote TYPE=CITE><font face="Times New Roman"><font size=+0>But I
don't think intercellular spaces could contribute much to radial transport
of liquid water in trees. The intercellular spaces would have to be very
well isolated from outside air otherwise they would embolize very easily.
My guess (and this is only a guess) is that intercellular spaces would
be water filled only from xylem pressure potentials of 0.0 to -0.15MPa.</font></font>
<br><font face="Times New Roman"><font size=+0>The accepted interpretation
(without lots of proof) is that intercellular spaces are a location of
stored water and such stored water is mostly gone by -0.2 MPa. But while
the spaces are filled with water they could contribute to radial transport.
See Xylem Structure and the Ascent of Sap (Second edition) by Tyree &amp;
Zimmermann, which is now in print from Springer!</font></font>
<br><font face="Times New Roman"><font size=+0>If you have any photos of
intercellular spaces I would be very interested in having copies. I think
we need more research on this topic.</font></font>
<br><font face="Times New Roman"><font size=+0>The story about ray cells
NOT being lignified is interesting to me. Does anyone have any citations
for that?</font></font>
<br><font face="Times New Roman"><font size=+0>Thanks,</font></font>
<br><font face="Times New Roman"><font size=+0>Mel</font></font>
<p><font face="Arial"><font color="#000000"><font size=-1>Melvin T. Tyree</font></font></font>
<br><font face="Arial"><font color="#000000"><font size=-1>Project Leader
NE4103</font></font></font>
<br><font face="Arial"><font color="#000000"><font size=-1>USDA Forest
Service</font></font></font>
<br><font face="Arial"><font color="#000000"><font size=-1>Aiken Forestry
Sciences Lab</font></font></font>
<br><font face="Arial"><font color="#000000"><font size=-1>705 Spear St&nbsp;
PO Box 968</font></font></font>
<br><font face="Arial"><font color="#000000"><font size=-1>Burlington VT
05402</font></font></font>
<br><font face="Arial"><font color="#000000"><font size=-1>Phone 802 951
6771 x 1310</font></font></font>
<br><font face="Arial"><font color="#000000"><font size=-1>FAX 802 951
6368</font></font></font></blockquote>

<p>--
<br>Guillermo Angeles.
<br>Instituto de Ecolog&iacute;a, A.C.
<br>Depto. de Productos Forestales y Conservaci&oacute;n de Bosques
<br>Km. 2,5 Carretera Antigua&nbsp; a Coatepec No. 351
<br>Congregaci&oacute;n "El Haya"
<br>91070 Xalapa, Veracruz
<br>M&eacute;xico
<p>Tel. (228) 842 18 35
<br>Fax&nbsp; (228) 818 7809
<br>&nbsp;</html>

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