Habitat pics - Las Vegas

[Guest]

Hi,

A habitat picture of Las Vegas itself, just look at the afternoon (14:00) smog.
[attachment 1748 vegas.jpg]

[Julie]

Hehe, our camp was in the middle of the German countryside...

[Vladimir]

You need some book on plant physiology. CAM, C4, Crassulian type methabolism. It has something to do with doing photosynthesis while not breafing and do the gas exchange business later at night - when it is colder and plant can save water this way, and is different chemicaly from the common C3 type. It is present in all cacti except Maihuienia at some stage of development and at least in some parts of plant.

[iann]

CAM is Crassulacean Acid Metabolism, a system where plants only open their stomata to absorb carbon dioxide at night. This is generally to reduce water loss during high temperature low humidity conditions during the day, but there are a few other situations too. CAM works by converting carbon dioxide into an acid which is stored in the leaves or stem at night, effectively a means of storing the carbon dioxide for later use. During the day, photosynthesis occurs and the acid is converted into sugars without any further need for carbon dioxide.

The benefits are obvious, water use is only 1%-10% of plants which open their stomata during the day. A major downside is slower growth due to the limits of how much carbon dioxide can be stored. There are other side effects such as increased sensitivity to external stresses due to the acid storage, and an inability to cool down using transpiration. Some plants switch between regular metabolism and CAM metabolism depending on whether conditions are suitable.

Almost all cacti as well as a high proportion of Crassulaceae, Aizoaceae, many other succulents, and some bromeliads all use CAM part time or full time.

[MikeT]

CAM = Crassulacean Acid Metabolism. Most (boring/ordinary) plants take in CO2 (carbon dioxide) which they metabolise with sunlight as energy source & give out O2, through their pores (stomata),in the daytime, and reverse this a bit in respiration at night. Most succulents couldn't afford to open stomata in the day, they'd lose too much valuable water. So they open stomata at night, take in CO2, and store this chemically as malic acid + isocitric acid. Next day, with sunlight, these acids are used in photosynthesis, so the plant can keep its stomata closed, avoid losing water, but still photsynthesise. The following night the stomata open, release O2 & take up more CO2.

CAM was first identified in the Crassulaceae family (anyone know which?), but occurs in many other succulent families -cacti, mesembs, portulacaceae, agavaceae, liliaceae, dioscoreaceae for example. there are some other related variations on plant metabolism with other organic acids than malic. These also occur in succulents.

There are 2 conclusions:-
1. succulents are clearly cleverer than ordinary plants, therefore match their owners
2. have succulents in your bedroom if you want extra oxygen; ordinary plants of course give off CO2 at night (basis for old idea of removing flowers from hospital wards at night, though hard to imagine it made any difference in an old draughty hospital ward)

[Julie]

Thanks, Vladimir, Ian and Mike (like the first conclusion! ).

Plants are so clever! I'll go and say goodnight to the forbies and mesembs, and think of them doing their clever stuff while I sleep.

[Cactus Jack]

Hi Bill Love The annimation !!

[Vic]

Yes Bob the smog in Vegas was disgusting - thick horrible brown stuff and just think if you live there you'd be breathing that lot in on a daily basis. I remember the same in LA. Talk about the greenhouse effect. How this country gets the blame for a lot of it when the Yanks are driving about in those big V8 gas guzzlers I do not know!!

Sorry no offence to our American friends - great country - great plants etc.......!!!!