A temporary water mount was prepared by mixing the dry powder with water and waiting until the material was fully hydrated.

SRM3254 is a very fine powder of a pale olive green color. It consists of a mixture of different-sized particles of two major types. Larger, multicellular particles are distinctly greenish in color, mostly <0.1 mm long and almost all <0.4 mm long, irregularly shaped and often somewhat angular. Details of individual cells are not readily discerned, but cells often appear irregularly rounded; portions that contain xylem tissue may give the appearance of containing parallel striations or lines of cells. Small irregularly shaped particles that are fragments of individual cells, not generally identifiable to cell type, are usually irregularly rounded rather than angular. Occasional short fragments of cylindrical xylem vessels showing helical thickenings will be observed; these are usually under 15 µm in diameter, and are occasionally found paired but usually not in larger clusters. Linear, unbranched, single-celled hairs are present; intact hairs are up to 0.6 mm long and 15 µm thick at the base, tapering at the apex, thick-walled but clear and translucent. Broken fragments of these hairs are also present. There are a few unusual smaller pieces of subcellular debris that display a variety of distinctly angular shapes, ranging from 11 to 24 µm in size (measured in a straight line from arm to arm, not along the outside of the structure).

*National Institute of Standards and Technology Standard Reference Material 3254.