The Henna tree has two special qualities: decomposing due to its warm watery essence, and constipating due to the cold earthly essence it contains.
I don't understand the meaning of "constipating here".
There are only two definitions of 'constipate' in Merriam-Webster:
Definition of constipate
1: to cause constipation in
2: to make immobile, inactive, or dull : STULTIFY
so much clutter … will tend to constipate the novel's working order
— The Times Literary Supplement (London)
I think both definitions aren't suitable for this context, but I'm not very sure. The word "decomposing" is also weird here. I don't think a tree decomposes just because of its essence.