Saxifraga is the largest genus in the family Saxifragaceae, containing about 440 species of holarctic perennial plants, known as saxifrages or rockfoils. The Latin word saxifraga means literally "stone-breaker", from Latin saxum + frangere. It is usually thought to indicate a medicinal use for treatment of urinary calculi, rather than breaking rocks apart.
Thelypodium howellii, the Howell's thelypody or Howell's thelypodium, is a rare plant of the Western United States. It is endemic to a relatively small area on the borders of three western States: Oregon, Nevada, and California.
Heuchera abramsii is a rare species of flowering plant in the saxifrage family known by the common names San Gabriel alumroot and Abrams' alumroot.
Allium howellii is a North American species of wild onion known by the common name Howell's onion. It is endemic to California.
Chorizanthe howellii is a species of flowering plant in the buckwheat family known by the common names Mendocino spineflower and Howell's spineflower. It is endemic to coastal Mendocino County, California, where it is known only from the sand dunes and coastal scrub near Fort Bragg. It is estimated that 95% of the remaining individuals of this plant are part of a single population growing at MacKerricher State Park. It is a federally listed endangered species.
Draba howellii is a species of flowering plant in the family Brassicaceae known by the common names rosette draba and Howell's draba. It is endemic to the Klamath Mountains of northern California and southern Oregon, where it grows in rock crevices. This is a tuft-forming perennial herb, sometimes coated in hairs. Most of the leaves are located at the base of the plant, each oval in shape, up to 2.5 centimeters long, and sometimes edged in fine teeth. There may be one or more leaves on the stem as well. The erect inflorescence bears up to 30 yellow mustardlike flowers. The fruit is an oval silique up to a centimeter long containing several seeds.
Lomatium howellii is an uncommon species of flowering plant in the carrot family known by the common name Howell's biscuitroot, or Howell's lomatium. It is native to the Klamath Mountains of southern Oregon and northern California, where it is a member of the local serpentine soils flora.
Lupinus flavoculatus is a species of lupine known by the common name yelloweyes, or yellow-eyed lupine.,
Minuartia howellii is an uncommon species of flowering plant in the family Caryophyllaceae known by the common names Howell's stitchwort and Howell's sandwort.
Mitella trifida is a species of flowering plant in the saxifrage family known by the common names threeparted miterwort and Pacific miterwort. It is native to western North America from Alaska to Montana to California, where it grows in wet wooded habitat types. It is a rhizomatous perennial herb growing up to about 45 centimeters tall. The leaves occur around the base of the stem. They have rounded blades up to 10 centimeters wide and lobed, round-toothed edges. The erect inflorescence bears up to 20 flowers, usually along one side of the stem. The distinctive flower is cup-shaped with five white or violet-tinged petals which are usually, but not always, divided into three lance-shaped lobes.
Montia howellii is a species of flowering plant in the family Montiaceae known by the common names Howell's miner's lettuce and Howell's montia. It is native to western North America from British Columbia to northern California, where it grows in moist to wet habitat, including vernal pools and meadows. It sometimes grows in shallow standing water such as puddles. The species is known from fossilized seeds recovered from sediments of the Pleistocene Tomales Formation and from a small paleoflora at San Bruno. Further, Daniel Axelrod discussed Montia howellii as one of the biogeographically significant species comprising the Millerton paleoflora at Tomales.
Orobanche valida is a species of broomrape known by the common name Rock Creek broomrape. It is endemic to California, where its two uncommon subspecies grow in mountainous habitats separated by several hundred miles. Howell's broomrape, ssp. howellii, is limited to the North Coast Ranges north of the San Francisco Bay Area, where it grows in chaparral, often on serpentine soils. The similarly rare subspecies valida is known from only four occurrences in the Transverse Ranges. The plant is a parasite growing attached to the roots of other plants, generally shrubs; ssp. howellii can often be found on Garrya species. The plant produces a hairy, glandular purple stem up to about 35 centimeters tall. As a parasite taking its nutrients from a host plant, it lacks leaves and chlorophyll. The inflorescence is a small cluster of tubular purple flowers 1 to 2 centimeters long.
Pedicularis howellii is an uncommon species of flowering plant in the family Orobanchaceae known by the common name Howell's lousewort. It is endemic to the Siskiyou Mountains of the Klamath Range in southern Oregon and northern California, where it grows on the edges of coniferous forests. This is a perennial herb producing one or more stems up to 45 centimetres (18 in) tall from a long caudex. The leaves are up to 20 centimetres (8 in) long, lance-shaped, and divided into many toothed oval lobes; those higher on the stem may be unlobed. The basal leaves fall away early. The inflorescence is a small raceme of flowers occupying the top of the stem. Each white to light purple flower is up to one centimetre long and is sickle-shaped, with a curved beak-like upper lip and a three-lobed lower lip which may be tucked into the hairy mass of sepals. The plant is pollinated by bumblebees including Bombus mixtus. Between the flowers are hairy to woolly triangular bracts. The fruit is a capsule just under a centimeter long containing seeds with netted surfaces.
Poa howellii is a species of grass known by the common name Howell's bluegrass.
Puccinellia howellii is a rare species of grass known by the common name Howell's alkaligrass. It is endemic to Shasta County, California, where it is known from a single population in Whiskeytown National Recreation Area near Whiskeytown. Its entire population is contained in a 1-acre (4,000 m2) complex of three saline mineral springs directly next to Highway 299. The grass was first described to science in 1990 and no other populations were discovered despite extensive searches of the area.
Micranthes aprica is a species of flowering plant known by the common name Sierra saxifrage. It is native to the high mountains of California, including the Sierra Nevada and the southern Cascade Range, and adjacent slopes in southern Oregon and western Nevada. It grows in mountain habitat in areas of alpine climate, such as meadows and next to streams of snowmelt. It is a perennial herb which spends most of the year in a dormant state in order to save water, and rarely flowers. It produces a small gray-green basal rosette of toothed oval leaves up to about 4 centimeters long. When it does bloom, it sends up an erect inflorescence on a peduncle several centimeters tall topped with a cluster of flowers. Each flower has five sepals, five small white petals, and a clump of whiskery stamens at the center.
Micranthes ferruginea is a species of flowering plant known by the common names russethair saxifrage and rusty saxifrage. It is native to western North America from Alaska and northwestern Canada to northern California to Wyoming, where it can be found in moist, rocky habitat in mountainous areas. It is a perennial herb growing from a caudex and rhizome system and producing a basal rosette of leaves. Each leaf is up to 6 centimeters long, thick and fleshy with large teeth along the edges. The inflorescence arises on a slender, hairy peduncle up to 40 centimeters tall. Thin branches bear flowers and reproductive bulbils. Each flower has spade-shaped white petals, the upper ones dotted with gold.
Streptanthus howellii is an uncommon species of flowering plant in the mustard family known by the common name Howell's jewelflower. It is endemic to the Klamath Mountains of southern Oregon and northern California. It grows in mountain forests on serpentine soils. It is a perennial herb producing a hairless, often waxy-textured stem up to 70 or 80 centimeters in maximum length. It is generally unbranched. The ephemeral basal leaves have fleshy oval blades with smooth or toothed edges, borne on petioles. Leaves farther up the stem are similar but smaller and narrower, with shorter petioles or none. They do not clasp the stem. Flowers occur at intervals along the upper stem. Each has a calyx of purple sepals under a centimeter long with purple-tipped yellow petals emerging from the tip. The fruit is a thin, smooth, curved silique up to 12 centimeters long.
Tauschia howellii is a rare species of flowering plant in the carrot family known by the common names Howell's umbrellawort and Howell's tauschia. It is endemic to the Klamath Mountains of far southern Oregon and far northern California, where it is limited to nine occurrences in the Siskiyou Mountains. It grows in mountain forests on gravelly granite soils, often among stands of Shasta red fir. Despite its rarity it is stable and not considered very endangered. It is a perennial herb growing 30 to 80 centimeters tall. It is hairless in texture. The thick leaves have blades which are divided into leaflets large, sharp teeth and edges curved up, and borne on long petioles. The short inflorescence is a compound umbel of yellow flowers on a few short rays. The fruit is oblong, ribbed, and just a few millimeters long.
Trifolium howellii is a species of clover known by the common names canyon clover and Howell's clover. It is native to Oregon and California, where it grows in moist and shady habitat types, such as swamps and forest streambanks.
