Crabapple

[svanhoeven]

I really like the atypical subject matter. In-line opinions on meter are below, since the other comments discuss it, though I am by no means an expert on meter:

Fresh water purged your xylem
OK, iambic trimeter with a feminine ending.
all through an ardent youth,
Still iambic trimeter.
from a sun-washed canopy
The first foot is an anapest. da da DUM. "from a SUN-washed..."
to subterranean roots.
The last foot is technically an anapest, i.e. "SUB /ter /RA /ne-an /ROOTS, but the reader can convert "ne-an" into one syllable pretty easily, so OK.

Your phloem coursed with glucose
when times were nutrient rich,
"Nutrient" informally OK as "subterranean" above.
but these fluids have gone foul;
Again, first foot is an anapest.
your bark is staining pitch.
"staining pitch"- Do you mean "stained by pitch", or "pitch that stains"? Ambiguous.

Your verdant crown has withered,
OK feminine ending.
its lofty haven breached.
Forsaken are those loved ones
OK feminine ending.
beyond your branch’s reach.

Limbs are bowing heavily;
It seems to me this line is trochaic with an extra syllable.
your swollen trunk is heaving.
OK feminine ending.
Verve drifts from languid shoots,
with each leaf deceiving.
Three feet, but the last two are trochaic.

Records in annual rings
One trochee and two iambs, as long as "annual" is read as two syllables. Could be a regional thing, but I read it as three syllables.
portray an ocher past,
but stagnant sap has thickened
OK feminine ending.
behind a shifting mask.

Your resin’s turning amber,
OK feminine ending.
as you yield to stony sloth.
First foot is an anapest.
The sky is painted umber
OK feminine ending.
beneath your soiled cloth.

With no more comforting shade
Last foot is anapestic.
to offer anyone,
why does your vague outline
Last foot is a trochee. I think in the first or second foot a single trochee would be OK, but not in the last foot.
cast a shadow on my sun?
I don't think the initial stressed syllable works. I see why you did it since you were trying to alternate stresses with "outline" in the previous line, but it didn't work for me.