Article from Bean's Trees and Shrubs Hardy in the British Isles
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'Hypericum grandifolium' from the website Trees and Shrubs Online (treesandshrubsonline.
A shrub to nearly 6 ft high in the wild. Leaves up to 31⁄2 in. long and 2 in. wide, broadly triangular-ovate to oblong-ovate, usually obtuse. Inflorescence with up to thirteen flowers from the upper two nodes, with spreading branches. Flowers golden yellow, 1 to 13⁄4 in. wide. Sepals spreading to reflexed, persistent in fruit. The fruits are dry when ripe, indehiscent.
A native of the Canary Islands and Madeira, allied to H. androsaemum and H. hircinum, differing from both in its greater size and larger leaves, from the former in its dry fruits and from the latter in its persistent sepals. Introduced to Kew in 1974 by Brian Halliwell.