Purple peyote seedlings - a sign of extreme conditions
A purple colored epidermis is a common stress indicator for a number of cacti - stress caused either by cold or draught - and consequently can be seen as a sign of extreme growing conditions.
The peyote seedlings in the above photo haven’t seen a drop of water since late August/early September, i.e. they have been without water for almost half a year. And the last time I checked, the temperature in the coldhouse where the seedlings grow had been as low as -10C (14F). Extreme conditions for peyote seedlings indeed! And the explanation for their purple hue.
The plants are grown from seed originating from El Oso, Coahuila, Mexico. Given the locality and the seedlings’ ability to endure extreme cold and dry conditions I expect them to be Lophophora williamsii var. echinata.
Speaking of purple Lophophora williamsii var. echinata the below photo was posted a while ago by Keeper Trout. The picture shows a patch of mature peyote turned purple by the cold. According to Trout, the area in Texas where the plants grow had experienced a "hundred year freeze" including three days where the highest temperature measured at a nearby locality was 10F (less than -12C).
Purple peyote in habitat in Texas
The frost in western Texas killed off a lot of things considered freeze-hardy - including the dead peyote pictured below. This plant was from a different population than the purple patch pictured above and might have seen slightly colder temperatures, but still it’s a good indication that the freezing temperatures these plants experienced are at the limit of what Lophophora williamsii var. echinata will stand.
Dead peyote in habitat in Texas
As mentioned at the beginning of this post a purple tinted epidermis is a common sign of stress in many cacti. Another example from my coldhouse is the purplish-hued Ariocarpus retusus pictured below.
Purple tinted Ariocarpus retusus (SB 310; Cuesta la Muralla, Coahuila)
The mature peyote photos are courtesy of Keeper Trout and the Cactus Conservation Institute and originate from this post on The Corroboree.
George Engelmann : Box 14: Folder 22: Euphorbia: undated (added: 03/29/2017) - *By:* Engelmann, George,1809-1884. *Call Number:* Archives Collection 1 RG 4/1/5/1 *Contributing Library:* Missouri Botanical Garden
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