OptionalsummerThe surface's own as-authored green — the reference the whole palette is
applied relative to, so high summer is exactly a no-op.
attachSeasonalTint defaults it to the material's color;
HexWorld resolves the terrain's from the pack (see
resolveFoliageColor).
OptionalspringColour of new growth, seen on the way up from bare. Default a fresh yellow-green.
OptionalautumnColour of the turn, seen on the way down to bare. Default a burnt gold.
OptionalbareWinter's dormant colour, at and below bareTemp. Default a grey-brown.
OptionalgreenSeason-adjusted temperature at or above which foliage is fully green. Default 0.5.
Optionalbare…and at or below which it is fully bare. Default 0.26 — above the snowline, so leaves turn before snow lies.
OptionalstrengthOverall strength, 0 (no tint) to 1 (the full palette). Default 1.
OptionalselectHow strictly the tint is confined to the green parts of the surface: 1 leaves bark, rock and sand alone, 0 tints everything evenly. Default 1; use 0 on a mesh that is foliage all over.
OptionalvarianceHow far individual plants stray from the shared autumn colour, 0–1. Default 0.5.
OptionalblossomPetal colour of a plant in bloom. Individual plants land somewhere between this and blossomAlt, so one wood carries a range. Default a soft pink.
OptionalblossomThe other end of the blossom range. Default a pale blue.
OptionalblossomFraction of plants that flower at all, 0–1. Default 0.5.
OptionalblossomHow thickly petals cover a flowering plant at the peak of the bloom, 0 (never flowers) to 1 (petals only). attachSeasonalTint switches this on at 0.85; it is 0 everywhere else, which is what keeps the terrain from flowering.
How foliage turns through the year. All fields optional — unset fields keep their current value. See FOLIAGE_GLSL for what each one does to the math.