Adjective
Petaline.
Source: Webster's dictionaryFlowers typically have two of their stamenoids (sterile stamens ) fused to form a petaloid lip, and have only one fertile stamen. Source: Internet
They are distinguishable by having one of the five petaloid sepals (the posterior one), called the galea, in the form of a cylindrical helmet; hence the English name monkshood. Source: Internet