Acanthomintha duttonii
| Acanthomintha duttonii | |
|---|---|
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Lamiales |
| Family: | Lamiaceae |
| Genus: | Acanthomintha |
| Species: | A. duttonii |
| Binomial name | |
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Acanthomintha duttonii (Abrams) Jokerst |
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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. The bracts in the inflorescence have marginal spines, thus the basis of the common name ‘thornmints’. All Acanthomintha have the upper three lobes of its calyx acuminate and the lower two lobes oblong in shape; furthermore, all Acanthomintha corollae are funnel shaped and white with occasional tinting of purple. Each Acanthomintha species has four stamens, with the upper two reduced. Thornmint styles are slender and their fruit is ovoid in shape with a smooth exterior texture.
A. duttonii has a stem which is generally unbranched and less than twenty centimeters in length; the stem may present short hairs or none at all. Leaves of this species are eight to twelve millimeters in length, lanceolate to obovate in shape. The margins of this spiny leaf are occasionally serrate. The terminal inflorescences have bracts of about five to eleven millimeters; moreover, these bracts are ovate and green at the flower, with five or seven marginal spines, each three to seven millimeters. The virtually hairless to sparse short haired calyx is five to eight millimeters in length, while the corolla is 12 to 16 millimeters in extent. The white corolla is often tinged lavender in color; the corolla throat is cream colored and its upper lip is hooded, while the longer lower lip is reflexed and three-lobed. The upper lip is more diminutive than the lower, and is entire and shallowly hooded. The flower bracts are broadly ovate in shape with puberulent hairs and shiny. The bracts have seven to nine spines each. The anthers are short and hairy. The style is glabrous. Plants bloom in April into late June, with each flower when fertilized producing four nut-like seeds. Plants are self-fertile. A. duttonii upper stamens are fertile, while the other species have sterile upper stamans. The presence of these fertile upper stamens is used to separate it as a different species from Acanthomintha obovata, in the past A. duttonii was referred to as subspecies of A. obovata (Acanthomintha obovata ssp. duttonii).
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Wikipedia