What are gardeners gaining from the commercial openness of China? The chances are that if you like a plant, it will ultimately derive from a Chinese habitat. The great plant-hunters of the early 20th century brought back trees, shrubs and bulbs from east Asia, which transformed our plantings in the west. In the 1960s, while those Chinese flowers supposedly blossomed under the pickaxes of the Revolutionary Guard, the gains for gardeners grew no more, but since the 1980s matters have improved, as returning botanists began to discover how much more remained to be introduced to gardens outside China.

One natural Chinese family has always been known but has been extraordinarily difficult for gardeners to acquire and cherish. The tree peony has had the highest status in Chinese art and culture but for decades it was difficult to find historic varieties in European nurseries. The most sought-after plant for connoisseurs was a lovely white with a dark central blotch on its big, ruffled flowers. Paeonia rockii had been discovered in the northern mountains of China by the great collector Joseph Rock. Its first growers emphasised how unusually tough it was in cold weather, drought and bug-infested gardens. Nonetheless, it almost disappeared from the trade. Ten years ago, my hands shook with excitement when I found two young plants of it in a West Country cold frame in the middle of nowhere. The proprietor quickly took them away and hid them, insisting they would never be for sale. I hope they are setting buds somewhere this weekend.