with needles that are …

___ flat, flexible  or

◼︎♦ 4-sided[?], | stiff and sharp, and twig=rough where needles fall off
spruce  genus Picea

◯ round with axial groves, segmented, tips have projections, looks like horse hair
🇦🇺 Australian pine or beach she-oak  Casuarina equisetifolia

Needles are ___ flat and flexible

and splay …

left + right + up + down + all angles  or

left + right a little more than up + down + all angles
fir  genus Abies

left + right (pretty much exclusively) :

Needles splay left + right pretty much exclusively

needle undersurface=whitish,
needle lengths differ from each other along stem, alternate, shed separately
hemlock  genus Tsuga

needle undersurface=not whitish,
needles shorter toward end of twig, opposite, shed together on their twig (look at base of tree)
bald cypress  Taxodium distichum