As found in nature, saltpetre generally forms aggregates of delicate acicular crystals, and sometimes silky tufts; distinctly developed crystals are not found in nature.
It dissolves in water with evolution of heat; on evaporation a basic salt, ZrOC1 2.8H 2 0, separates out in star-shaped acicular aggregates.
Iodine dissolves in an aqueous solution of the salt to form a dark brown liquid, which on evaporation over sulphuric acid gives black acicular crystals of the tri-iodide, K1 3.
Elongated, cylindrical, rounded at both ends; thick cuticle with acicular spicules; radula polystichous or wanting.
In Pinus the only leaves produced on the main stern and the lateral shoots are scales, the acicular leaves of the tree growing from axillary shoots.