Preparation of Opuntia herbarium specimens

We present a best-practice method for preparing high-quality Opuntia herbarium specimens, from collection methods to storage. A botanical press having wide, thick, wooden boards is used for cladode drying. A layer consisting of corrugated cardboard, absorbent paper, newspaper, and a thin wood laminate is placed between each cladode. The botanical press is placed in a forced-air furnace at 50-90°C. In the case of nopalitos (young, developing cladodes), podaria are first removed from one side, followed by drying at 45-70°C. Flowers are pressed immediately after collection at 45-60°C. Fruits are preserved in 70%25 ethanol. Seeds and pulp are removed, and empty fruits are immersed in alcohol for one month; afterwards they are removed from the solution and washed. Fruits are then drained, stuffed with fine sand, and placed in a forced-air furnace at 40-45°C. Finally, the sand is removed and the cavity is filled with resin.

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