The Kurogane Holly or Round Leaf Holly is perhaps the rarest of the many hollies that occur in Jungle Gardens. Do not confuse this tree with the more common Ilex cornuta var. rotunda. They are very different. Only four large trees and two small ones are known to occur in the gardens. All of the large trees are female so unfortunately none of their fruits produce viable seeds. It is one of the most attractive Holly species in cultivation, producing tremendous clusters of bright red berries in fall months. Their dark green leaves are spineless as is the entire plant. This evergreen tree can reach a height of 50 feet. Those in the gardens are all of similar height, 30+ feet, suggesting they were planted at the same time. All of these occur along Palm Garden Road. In 2018, two additional Round Leaf Hollies were discovered at the edge of a wooded area, not far from one of the mature trees. Both of these trees are near one another, both are 6 feet tall and 1 inch in diameter, suggesting they are young plants of similar age and originated from seed. This gives hope that a male tree could exist in the area but has remained undiscovered. Careful scrutiny of the flowers on all of the mature trees is needed in early spring to see if some of them might also be producing some pollen bearing flowers.
Kurogane holly was first described in 1784 from Japan. This species of holly is one of the recognized Hibakujumoku trees. Hibakujumoku is the Japanese term that refers to trees that are known to have survived the bomb at Hiroshimi in 1945. The Kurogane Holly is also the official tree of several Japanese municipalities.