Hypocalymma verticillare is a species of flowering plant in the myrtle family Myrtaceae, and is endemic to the south-west of Western Australia. It is a shrub, with egg-shaped to elliptic leaves, and white flowers with 17 to 23 stamens.
Hypocalymma verticillare is an erect shrub that typically grows to high and has slender, glabrous, prominently ridged young stems. Its leaves are egg-shaped to elliptic or narrowly elliptic, long, wide on a petiole wide. The edges of the leaves are curved down or rolled under, and the lower side of the leaves has many oil glands. The flowers are arranged in up to ten leaf axils on a peduncle long with bracteoles long but that fall off as the flowers open. Each flower in diameter on a pedicel long, the floral tube long and wide. The sepals are egg-shaped, about long and wide, dark red and white. The petals are white, long and there are 17 to 23 white stamens, the longest filaments long. Flowering occurs from March to May and the fruit is a capsule about long and in diameter.[1] [2]
Hypocalymma verticillare was first formally described in 2013 by Barbara Lynette Rye in the journal Nuytsia from specimens collected north-east of Walpole in 2005.[3] The specific epithet (verticillare) means 'whorled', referring to the leaves.
This species of Hypocalymma grows in peat swamps in shrubland in the Jarrah Forest and Warren bioregions of south-western Western Australia.
Hypocalymma uncinatum is listed as "Priority Two" by the Government of Western Australia Department of Biodiversity, Conservation and Attractions, meaning that it is poorly known and from one or a few locations.[4]