three-valved
Adjective
Meaning
Consisting of, or having, three valves; opening with three valves; as, a three-valved pericarp.
Source: Webster's dictionaryExamples
The samara fruit is an oblong, three-valved capsule, which contains one to three seeds.
The seeds are produced in a small three-valved capsule, maturing in summer.
Thus, even three-valved instruments with good alternative resonances can produce very low sounds in the hands of skilled players; instruments with four valves can play even lower.