Re: CAM in aroids?

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Aroiders,

Is anyone aware of research into CAM photosynthesis in aroids, beyond Zamioculcas zamiifolia?

While digging into something else entirely, I came across a paper (Silvera et al, 2009, "Crassulacean Acid Metabolism and Epiphytism Linked to Adaptive Radiations in the Orchidaceae") which suggests that CAM is linked, statistically anyway, to low elevation and epiphytism - in the Bromeliaceae and Orchidaceae.

This caught my eye:

"CAM vascular epiphytes (mostly orchids and bromeliads) are an important component of the biomass and species richness of tropical forest canopies (Benzing, 1987; Lüttge, 2004; Zotz, 2004). Bromeliads, aroids, and orchids are three of the very few flowering plant lineages that were able to successfully colonize epiphytic niches (Gentry and Dodson, 1987)."

Another paper (Holtum et al, 2007, "Crassulacean acid metabolism in the ZZ plant, Zamioculcas zamiifolia (Araceae)") says:

"The majority (>90%) of epiphytes with CAM are in the monocotyledonous families Bromeliaceae (Poales) and Orchidaceae (Asparagales)."

There's a lot of research suggesting that CAM has evolved many times independently, even within single families, and it also occurs widely - the Holtum paper says 29 families and 338 genera of angiosperms, as well as (more rarely) in other more distant branches of the plant kingdom. Aroids are very successful tropical epiphytes, by one estimate second only to orchids - did they not get the CAM memo, or has no one looked? Or did I just miss the research in my Googling?

Thanks,

Steve

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