Spike Length

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Orchid Iconoclast
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Supporting Member
Jun 9, 2006
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Oak Island NC
What are the most significant factors controlling spike length in paphs?

There seem to be some variation happening in my collection, and I'm not certain what might be going on. The strap-leaf types seem to be pretty consistently tall, but the mottled-leaved ones seem variable, growth-to-growth, year-to-year, and this year they seem shorter than in the past.
I would think light. Most of mine that are grown in lower light levels have longer stems.
I agree with Rose. Light levels will effect stem length. If they're shorter this year you've had higher light conditions. Of course, parentage does play a role.
I'm ignoring parentage, since what I'm seeing is a difference from the last time these same plants bloomed on different growths.

I don't know that what I'm seeing is light related either, as the greenhouse roof is quite crudded up (it'll be cleaned next spring/summer), and I doubt that this fall/winter has had more sunlight that in prior years.

FWIW, the plants themselves are significantly bigger than before - leaves almost double the size, and more leaves per growth.
Hey Ray
My thoughts, stem length is an interaction between several factors
1.) Light intensity, more light, shorter stems. Less light - longer stems
2.) humidity - humidity significantly lower than the ideal may shorten stems
3.) Temperature - I think the hotter it is the shorter the stems, but I am less certain here.
4.) somewhere I read that light spectrum can influence cell elongation, more of either blue or red drives cell elongation, but this is in my vague and mostly forgotten part of my memory. You being in the spectra business might remember the literature better than me.

I have seen wide variation in stem length on a given plant, most notable in my complex paphs, but the causality has not emerged from the pattern yet for me either.
I really liked Leo's answers, and as far as environmental control I think they are right on.

When he mentioned cell elongation it reminded me of some to the research I'd seen on common plant hormones, such as the cytokinins and auxins. Some are responsible for cell differentiation and some cause growth and elongation.

The production of these is probably regulated primarily by environmental issues in the wild, but in controled environments they may be heavily influenced by the nutrition of the plant too.
No photos readily available, but in a couple of cases, I have gotten huge blossoms on inflorescences so short, it looks like the flowering is occurring right at the crown! One, a typical Maudiae type, opened "face down" in the leaves.

I think it's interesting that it's only the mottled-leaved plants that are affected.

These are plants that have gotten literally the same feeding regimen and fertilizer brand at the same concentration for 5 years, so that should be the issue either.

If I get home early enough today, I'll try to remember to grab a couple of pics.
Another weird observation:

It appears that the spike length is reasonably normal in the end, but what seems to be happening is that the flowers grow and develop sooner than I've ever seen before, with the spike extending later.

OK. No harm, no foul....I guess.
So do I, but it is not pertinent in this case, as I'm talking about a change from former years, not differences between plants.
I like Leo's answer, especially about temps. When plants are repotted, or are stressed somehow, they often change the time of flowering, either earlier or later than usual. Length of flower spikes that grow during winter months are frequently different from those (same plants) they produce when they are well established in their pots. The stems can be longer, or shorter, depending on the plant, too, at this time.
I have a "Maudiae type" of Paph that I divided last spring. I considered both pcs. to be equal in maturity, I grew them together side by side. Both spiked at the same time but one has a flower height of ~18 inchs the other ~12. The flower itself on the 18 inch appears to be larger as well. I figured with everything the same, that it had to do with establishment ( such as, root growth of one over the other pc.) If I can get a PIC of the two tonight I'll post it.
Ray, I believe Leo is correct in what he wrote, temp, light, humidity etc can have an influence in flowering...but... I reckon that the local climate, seasonal variations, even though plants may be grown in somewhat controlled environment, can effect the way plants flower. Where I live, we can have dry, hot & windy summer followed by warmish dry winters or wet, humid & calm summers and cold, wet windy winters. The following flowerings on my orchids can & have been in some case quite different to the previous.
At the moment, a number of Paph growers, including myself, are flowering plants 6 months out of season. None of us can find anything we have done greatly different in our culture. The variant is the outside climate extremes.
Precisely what I was trying to find out, Roy. All plants are affected by such environmental factors, but they do not necessarily react the same, so I was shooting for a definitive answer about which in paphs.

I had not considered the "how well established" aspect, but as they have not been repotted (some for several years - S/H culture), I'd have to rule that out, too.
I believe that different environmental changes affect Paphs in a way that can be releated to where the species Paph comes from or the species in the background of the hybrid. By this I mean, that to my knowledge, there are no Paphs in the wild that grow 365 days of the year in ideal conditions as we provide in cultivation. Most species adjust to cultivation in a positive way and excell. Hybrids know almost nothing of the natural environment and thrive in cultivation. Once this cultivation environment is interupted, the variations in growth or flowering occurs. How well a plant is "established", to me is a factor, one with an average root system will react more quickly than a plant with a first class root system. I believe its the "maturity" of the plant that is the key. A plant with a good root system and multiple growths, flowered or not will be less likely to vary greatly year to year. There is aways the fact that normal variations in flowering will & do occur in the best of conditions.
Ray, Roy, et al,

Just got this email announcing the availability of a new book that may have your answer. Let me preface this by saying I don't know the authors (editors). And I have no vested interest in the sale of this book.

Cell Division Control in Plants
Series: Plant Cell Monographs , Vol. 9
Verma, Desh Pal S.; Hong, Zonglie (Eds.)
2008, X, 417 p. 60 illus., 18 in color., Hardcover. List Price: $209.00
Sale Price: $188.10 + shipping and handling ($8.00, U.S. or $20.00 Elsewhere)

The molecular mechanisms controlling cell cycle progression are highly conserved in eukaryotes. In addition to the basic protein machinery involved in cell cycle regulation, higher plants have also evolved unique molecular mechanisms that allow integration of environmental, physiological, and developmental signals into networks to control proper cell division and expansion. Rapid and exciting research progress in these fields has been achieved from experimental observations on plants over the past decade. The scope of this volume is focused on the molecular basis of all aspects of cell division and cytokinesis in plants. It is an essential reference book for instructors and scientists working in the areas of molecular, cell, and developmental biology of plants. The editors of this book are veterans in the field of plant molecular biology and highly respected worldwide.

Part A Commitment for Cell Division and Cell Cycle Control.- Circadian Regulation of Cell Division.- Transcriptional Control of the Plant Cell Cycle.- Division Plane Orientation in Plant Cells.- G1/S Transition and the Rb-E2F Pathway.- The Endoreduplication Cell Cycle: Regulation and Function.- Part B Dynamics of Chromosomes, Cytoskeletons and Organelles During Cell Division.- Chromosome Dynamics in Meiosis.- Cytoskeletal and Vacuolar Dynamics During Plant Cell Division: Approaches Using Structure-Visualized Cells.- Mitotic Spindle Assembly and Function.- Cytoskeletal Motor Proteins in Plant Cell Division.- Organelle Dynamics During Cell Division.- Open Mitosis: Nuclear Envelope Dynamics.- Part C Cell Plate Formation and Cytokinesis.- Map Kinase Signaling During M Phase Progression.- Plant Cytokinesis - Insights Gained from Electron Tomography Studies.- Vesicle Traffic at Cytokinesis.- Molecular Analysis of the Cell Plate Forming Machinery.- Part D Cell Division and Differen tiation.- Asymmetric Cell Divisions: Zygotes of Fucoid Algae as a Model System.- Stomatal Patterning and Guard Cell differentiation.- Genetic Control of Anther Cell Division and Differentiation.- Coordination of Cell Division and Differentiation

A little too pricey for a retiree, but hopefully it'll become available someday through the Library to Library Loan program.

charlie c
OK, here are the pics I mention in an earlier comment.
and a slightly better look at the plants.

This is an OZ cross, P. Florence Coyner ( Incantation X wardii) As I and others have mention, estabishment. Better root growth on the left plant vs. the right. Have you knocked one of your weird acting plants out of the pot and checked out the un-seen?

Another thing that hasn't been mention (I don't think has) is insecticide. Have you treated lately, maybe a round the bud formation time period? I find that to be a problem with plants/flowers at times.
Root system looks good, leaf growth is better than ever, no insecticides.

Here's one example P. (Onyx x Grand Illusions) Spike length is only about 3"below the bud.