long, tall
short
thick
slender, thin
main
flexible, strong
brittle, weak
flowering, woody
flower, plant
iris, rose, etc.

break, cut, cut back, prune, prune back, remove, shorten, trim
When the bush has finished flowering, cut back all the stems.

break

on a/the stem
There are several leaves on each stem.

the base of the stem
Cut half an inch off the base of each stem.

Stem is used with these nouns as the object:
bleeding, corruption, decline, flow, haemorrhage, spread, tide