Purple Cactus seedlings?

[Benzito]

I germinated a bunch of Lophophora and Trichocereus seeds, around the end of last Summer.

They have powered along all winter, in their nice, humid little styrofoam box.

And, about a month ago, I took the glad-wrap off the top, and replaced it with Muslin, held on by elastic.

I still mist them every few days, and they stay slightly moist most of the time.

I plan to remove the Muslin in a few weeks time, and start hardening off.

Anyways, over the past month or so(? roughly) some of them have turned a purple colour. Not a specific species, and only a few out of each batch.

What the heck is that about? They're fine otherwise. In all honesty, it's probably some of the bigger guys that are purple. Maybe they're cold? :D hehe

Any ideas? I don't have a digital camera unfortunately.

[AndyAmine.]

Hi Benzito,

A few of my cacti had purple on them from to much sun., I would try reducing the intensity of light.

On the other hand, Ive heard buds can turn purple due to the cold.

[trucha]

Cold (light frosts) can cause purple in Cannabis buds or a bunch of other plants such as Justicia pectoralis. Its a really bad thing to notice in the latter as it often preceeds death.

In cactus seedlings its usually a warning sign of a bit too much light. They'll probably survive it just fine but ther growth rate may slow down substantially.

Try blockign the light with a thin sheet of paper for a few days (or until they start greening again) and see if you can transition them back into the present level.

Bronze or a more reddish color can also result from too much light but would require prompt attention to prevent death or injury.

[Gunter]

Some of my most vigorous specimens display this purple coloration, it is most pronounced under the areoles. Specifically it is very common on my SS02 hybrids and shows up much more frequently (in my own collection) on bridgesii allies than in other 'species'

Some have called it sunburn, and I wish to state that is it in no way sunburn, it is a pigment response to bright conditions, it is not damage at all. My sunburned plants never show it prior to being damaged and permanently injured by the sun.

Some cacti, such as my favorite Gymnocalycium and Rebutia species show very similar purple pigmentation in bright conditions but rather than being a symptom of adverse or overly bright conditions, this wonderful trait shows up in ideal conditions.

I have noticed the same purple pigmentation in seedlings under lighting that could not be described as bright at all. I suspect that in some species it is a response that has a lot to do with the spectrum and not the level of brightness. I have taken purple plants out from under florescent lights and put them in brighter sun lit conditions to have the purple coloration all but disappear.

I think it is a trait that should be considered a sign of health and an indication of optimum light levels, unless it is unusual for the specific clone and associated with stunted growth.

I would like to see more on the chemistry and identity of the purple pigment in Trichocereus.

[trucha]

In the species you mention purple is normal, in the cases of some Rebutias and others, its absence could be a sign of poor health and/or some sort of stress.

I've never seen it on my SS02 or any of my trichs yet. It would be interesting to know the differences in our growing conditions.

The Trichs around here (north of SF) often get darker with age and good sun exposure but it is more of a mottled darkish-olive than purple.

On peyote purple is not a normal or positive thing. It does not appear to be harmful to the plant but the plants will return to blue-green if the light level is cut down temporarily and then start growing faster. If its under fluorescents, moving it a couple or three inches away will generally restore it to its normal color within no more than a few weeks. Especially if the seedlings are small, this can make a big difference in that first year or so.

I think that I've only seen this on peyote seedlings or grafted pups not adults.

[Benzito]

Thanks everyone! It's so great to have so many experts answering my stupid questions.

These guys have never really been in any high-light levels though. Maybe 3-4 hours, filtered sunlight, per day.

But, never anything direct.

Trout, do you have any photo's of cactus seedlings growing in the wild? With all the effort they require to get growing, it seems like they almost wouldn't be able to grow without some human assistance.

A picture of the kind of light levels these dudes are normally exposed to might help, and I can't think of a single picture like this that I've ever seen.

I have constantly been worried that I might not be giving them enough light, so I'm surprised you guys think it might be too much. (But, that's why i asked, cause I don't know)

I remind you aswell: the biggest guys, are generally the purple ones.

Any further thoughts from anyone?

[Flip]

imo,

The seedlings are reacting to too bright of light

I've had this happen with my tricho seedlings

when I've exposed them to direct light early on in their lives.

resulting in their halting of growth for a few weeks....

growth returning with green coloration.

Call it sunburn if you will...

These plant are not "difficult to grow" in fact they're easy

if you just let them be "benign neglect" usually works best.

In the wild the landscape is not a flat open field of tilled earth.

Rather it's a bushy, rocky mountain slope that the plants

are shown in pictures growing in.

It's not that difficult to imagine that a small seed get

"pecked out" of a fallen fruit by a bird or is passed via the

GI track far away from the mother plant. where it settles in between

the gravel and may perhaps be also shaded by some plants (as with peyote).

There it can have both protection from the harsher elements

as well as a means of protection from rapid evaporation with seasonal rains.

It'll slowly develop there away from direct light until it's much older.

They're not perennial herbs that grow fast and die young

[Gunter]

I need to see if I can borrow a camera to illustrate what I am talking about with some very vigorous specimens.

I need to clarify my SS02 plants do not show it, neither do my pachanoi (Backeberg?) however my pach X SS02 and my SS02 X pach occasionally show it. In these cases the plants themselves are mostly a nice green color, but under the areoles on the skin, and near the base of the plant a lovely purple pigment is quite apparent.

One of these plants is an SS02 X T pachanoi that has 6 pups growing from its base, the plant itself is less than 15cm. It is growing quite well in conditions identical to its siblings, most of whom lack the coloration.

Sunburn results in scarring and eventually callus tissue, a big scab forms over the affected area.

I have seen the pigment show rather constantly on seedlings about 30 cm beneath 4 40W fluorescent tubes, all of the seedlings growing quite well. In the same conditions the SS02 X pachanoi seedlings show the coloration, but scopulicolus and SS01 X juuls and SS01 X pachanoi do not.

I want to disclaim though, I am no expert and this is just my personal experience. Though Trout is humble enough to say he isn't an expert, I hold his opinion in high regard. Likewise I hold Flips opinion high as well. Not to mention the numerous adept cactus growers here at this site.

I might suggest that the coloration may have something to do with UV, I am at about 4500 feet elevation in a temperate location. The fluorescent lights also have a high UV spectrum content. I could be quite wrong about this though.

I think some others have noticed the purple areole trait as well, but I'll leave it to them to mention it or not. Interestingly enough it does not show up much in my SS02 X ? plants.

[ 10. September 2005, 04:55: Message edited by: Archaea ]

[Flip]

Thanks for the nod Archaea

You're certainly no slouch either!

and I certainly don't wish to come off as a know it all.

I'm going to check out all my plants tomorrow morning to see if there's any coloration.

I don't expect to find any as my plants are now only getting

mostly early morning and late in the day light

everything else is indirect/shaded light.

If your theory is correct re: UV light exposure that would be interesting....

heck any "discoloration" will be worth noting.

[gusto]

I think we're all in agreement that the purple coloration is a response that's mediated by light levels, and a completely purple Trichocereus is likely in brighter than optimal conditions.

I can, though, second Archaea's observation of purple areole coloration in completely happy seedlings. So far I've only seen this in several hybrids with SS02 parentage, and in a batch of young KK919 (bridgesii) seedlings.

I suspect that the plants in question will outgrow the blushed areole response as they mature, so the trait may be of little value in identifying the lineage of undocumented clones. But it is quite interesting that so far the trait has only shown itself on those plants with some bridgesii genes.

[Gunter]

The first are Pachanoi X SS02 (Sorry about ruining this for dial-up

A SS bridgesii from seed.

[strangebrew]

Somewhat similar to the reaction Myrtillocactus geometrizens display in strong light yes?

[Flip]

Thanks for the images

As I said on another forum,

I have never seen this before

on any of my plants as mature as these.

I have had a few newly germinated seedlings "burn" like this

where their entire bodies turned the same purple hue.

Those were the result of my premature exposure to strong sunlight.

[ 13. September 2005, 22:43: Message edited by: Flip ]

[Gunter]

This is what sunburn has always looked like to me, I have never had the plants damaged thus show pigment before damage, rather they have a pale bleached look.

[ 13. September 2005, 23:06: Message edited by: Archaea ]

[Flip]

yeah that's what I would call scaring

that followed a really bad sunburn.

I've had the discoloration and it take a few weeks for that to clear up

[Gunter]

I have never seen a sunburn in cacti that did not result in damage like that.

I do not consider the pigment a burn, perhaps it might be comapred to a tan? I think there is more to it than intense light though.