Re: Taro Anomaly (Pictures)

At 10:09 PM 9/5/2002 -0700, you wrote:

>
>Side view showing "conjoining"
>
>Anyway, there you have it. What the pics don't show is
>that the stem is much thicker than usual, and it looks
>like there are spots where new leaves can emerge on
>either side of the stem. It's like the terminal bud
>developed two leaves at the same time and they fused. 

I've seen various instances of fastigation (from Latin 'sloping to a point')
where multiple branches emerge from a node and have connective tissue
between them for  part of the distance.  This feature reminds me of sci-fi
modified humans with webbing between their fingers as if they were modified
to live underwater.  

I wish I had saved the leaf on a Salvia cutting I just struck.  It was a
Siamese twin, and had a double vein structure which I could trace back
through the vascular bundle of the leaf petiole to the abnormal node on the
main stem.  One pair of the four corner nodes were also joined, and the stem
zigzagged from node to node as a result.  

I once had an Aloe vera that showed a spectacular example of this.  Most of
the pot was taken over by a wavy ridge of short conjoined stems.  It became
my favorite stock plant, since I could break off the short stems and root
them nicely.

A possibly related effect is that I occasionally get axillary growth on
various Lamiaceae with six vascular bundles instead of four, and that I get
whorls of three leaves off of a hexagonal stem.  Nodes off of these stems
revert back to four-fold symmetry.

Also, there is the case of Westringia, a genus of Lamiaceae where octagonal
symmetry is normal.  I've noticed that some cuttings of these plants send
out stems with square or hexagonal cross-sections on the initial axillary
growth, and that these disappear quickly into its normal eight-fold symmetry
with the following branching.

I seem to remember that this effect is at least sometimes caused by a
bacterial infection.  I once had a Salvia purpurea that developed an
apparent callus growth where the lowest nodes should have been.  Instead of
one or a few main stems, there were a plethora of small stems with stunted
leaves.  Many of these would die off, leaving a few more normal stems to
grow.  The effect persisted with plants made from these cuttings, and I
eventually replaced my stock.  

Perhaps there are biological agents producing compounds like gibberelic acid
that cause these effects.  Comments by plant pathologists will be welcome.

Richard F. Dufresne
313 Spur Road
Greensboro, North Carolina  27406 USA
336-674-3105
World of Salvias:  http://www.eclectasy.com/gallery_of_salvias/index.htm
Salvia email list:   http://groups.yahoo.com/group/Salvia
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