Date: Tue, 26 Sep 2000 10:07:36 +0000 From: Borneo Exotics <borneo@sri.lanka.net> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2868$foo@default> Subject: Re: Seasonal Production of Nepenthes Pitchers
Hi Jay,
Very interesting. I wonder if your conditions are really highland
tropical, i.e. are you at altitude? Light intensity at high altitudes in
the tropics is really very high and many highland Nepenthes grow in highly
exposed locations on mountain ridges etc. Prolonged periods of cool misty
weather are quite rare as there is at least some direct sunlight most days.
In the 1980s there was a period of several months when smoke haze
blanketed the whole of Borneo due to massive peat fires in Kalimantan and
sulight was filtered. Pitcher production on both highland and lowland
Nepenthes seemed to practically cease during this time. Of course, a smoke
screen such as this would probably also distort the sun's spectra and
perhaps that was another factor.
Another possibility is that a sudden drop in humidity at some time during
the day, even for a relatively short period, can inhibit pitcher
production. We found this in one of our shadehouses which overheated for
about two hours each day with a corresponding drop in relative humidity.
Larger plants pitchered 'as an afterthought' in exactly the manner you
describe, but smaller plants pitchered normally, probably due the existence
of a humid micro-environment near the potting media. We managed to
overcome this problem eventually by using evaporative cooling on the
fiberglass roof. Nepenthes don't like sudden changes towards the extreme,
although if given time they can adapt to a surprising range of (constant)
conditions.
Finally, if the mature plants you describe are producing upper pitchers,
then the factors influencing pitcher production may perhaps be different
than for lower pitchers (?). It seems to me that a climbing stem is often
more "interested" in reaching for the sky to flower than in catching
insects, which is a mundane chore it leaves to the pitchers lower down. In
my experience, the further the leaf is from the base of the plant, the
easier it can be dissuaded from bothering to produce a pitcher.
Hope this helps,
Rob Cantley
Jay wrote:
I am curious as to whether other members of this forum who cultivate mature
Neps have noticed a certain "seasonality" in pitcher production. My
conditions are highland tropical, and while my small TC plantlets in the
conservatory do the young rosette plant "thing" (new leaf = new pitcher)
many of my mature climbing plants growing outside appear to add several new
leaves before, almost like it was an afterthought, consolidating growth by
inflating pitchers on back buds. Thus far this appears to be most evident on
the N. maxima group of species and N. sanguinea. What is curious is that the
very conditions I would have expected to generate greatest pitcher
production in "highland" Neps (i.e. prolonged periods of cool, misty,
overcast conditions) seem to accentuate this growth pattern.
Am keen to receive feedback on this.
Regards -
Jay Vannini
This archive was generated by hypermail 2b30 : Tue Jan 02 2001 - 17:35:13 PST