Balsamea: Answers to key questions leading to this genus. 

Needles borne singly along branches, not in fascicles scaly-sheathed at base or on short shoots.  NOT [Needles on year-old and older branches borne either in groups (fascicles) of 2 with each fascicle scaly-sheathed at base at least when young, or in clusters of 12-25 on short shoots with clusters not scaly sheathed.]

Needles flattened, frequently grooved adaxially, usually rounded or notched at apex, flexible; seed-cones not falling whole but scale by scale, leaving naked cone axes persisting as erect "spikes" on branches; twigs not roughened by decurrent, projecting, peg-like leaf-bases.  NOT [Needles 4-angled in cross-section, either sharp-pointed or blunt-tipped, rigid; seed cones falling as a unit, not disintegrating by shedding scales individually from cone axis; twigs conspicuously roughened by decurrent, spreading or appressed, peg-like projections (pulvini) persisting after needles fall.]

Pinaceae: Answers to key questions leading to this family. 

Leaves needle-like, alternate or fascicled/clustered, shed individually from branchlets (usually shed as fascicles in Pinus); seed cone scales imbricate; seed cones dry; seeds adaxial and 2 per scale.  NOT [Leaves needle-like or scale-like, alternate, opposite or whorled, persistent on shoots, shedding with branchlets with age; seed cone scales fused or imbricate; seed cones berry-like (Juniperus) or dry (Thuja); seeds adaxial or terminal and 1-20 per scale.]