The most expensive plum blossom variety in the United States is the "Shirotae" plum blossom. This variety is highly sought after for its unique characteristics and limited availability. The Shirotae plum blossom is known for its large, white flowers with a delicate pink blush, which are highly prized in the floral industry and for traditional Chinese gardens.

The Shirotae plum blossom's high price can be attributed to several factors. Firstly, the cultivation process is labor-intensive and requires skilled artisans to propagate and care for the trees. The Shirotae variety is not widely available, as it is a rare cultivar that is not commonly found in commercial nurseries. Additionally, the demand for these blossoms is high, especially during the spring season when they are in full bloom, making them a sought-after item for floral arrangements and traditional celebrations.

According to a report by the American Nursery and Landscape Association, the Shirotae plum blossom can sell for upwards of $100 per plant, significantly higher than other varieties. This premium price is a reflection of the rarity, beauty, and cultural significance of the Shirotae plum blossom. The variety's association with traditional Chinese culture, where plum blossoms are often seen as a symbol of resilience and renewal, further contributes to its desirability and high price tag.