San Mateo Thorn-Mint

Description

Acanthomintha duttonii is a species of annual plant endemic to San Mateo County, California in the Lamiaceae family. It is commonly called San Mateo thornmint or Dutton's acanthomintha and is found growing on serpentine soils near the Crystal Springs Reservoir in a six-mile (10 km) long strip on the east side of Montara Mountain at elevations of approximately 150 to 300 meters. This rare annual species of wildflower has populations that fluctuates yearly with recorded population ranges from 50,000 plants to as few as 5,000 plants and is considered critically endangered due to the species narrow range of growing conditions and the fragmented nature of the populations over the limited habitat and by the encroachment of urban development. The species is named in honor of Harry Arnold Dutton (1873–1957), who, in 1949, located a patch of another rare plant Cupressus abramsiana on nearby Butano Ridge. All four thornmint species are aromatic annual wildflowers native to the state of California in the USA. The species have square stems that are erect growing. The leaves are petioled with leaf veins conspicuous and the leaf margins are often spiny. The Inflorescences of the Acanthomintha genus are described as "head-like, in terminal clusters" by the genus authority James D. Jokerst. The flowers of this entire genus are like, most mints, two-lipped forming a tube with five sepals and the stamens enclosed within the zygomorphic petals.