Noel Herman Holmgren

Euphorbia aaron-rossii, also known as the Marble Canyon spurge, is a perennial, herbaceous plant species of Euphorbia native to Arizona. It's most closely related to E. strictior and E. wrightii, but needs more study.

Allium passeyi is a plant species endemic to Box Elder County in northwestern Utah. It grows in shallow, stony locations at elevations of 1400–1600 m. Allium passeyi produces 2-3 round to egg-shaped bulbs, each up to 2 cm in diameter. Flowers are bell-shaped, up to 9 mm in diameter; tepals pink; pollen yellow.

Penstemon patens is a species of penstemon known by the common name Lone Pine beardtongue. It is native to the central Sierra Nevada of California and slopes and plateau to the east, its distribution extending just into Nevada. It grows in forest, woodland, and scrub habitat types. It is a perennial herb producing hairless, waxy stems up to about 40 centimeters tall. The thick, lance-shaped, gray-green, opposite leaves are up to 9 centimeters long and 2 wide. There are usually many leaves clustered around the base of the plant and smaller pairs higher on the stem. The inflorescence bears

Penstemon barnebyi is a species of penstemon known by the common names White River Valley beardtongue and Barneby's beardtongue. It is native to the mountain and basin territory of central western Nevada, where it grows in sagebrush and woodland; there is also one occurrence just over the California border.

Asclepias welshii is a rare species of milkweed known by the common name Welsh's milkweed. It is native to southern Utah and northern Arizona, where there are four known occurrences remaining. Most of the plants occur in Coral Pink Sand Dunes State Park, where the habitat has been degraded in many areas by off-road vehicle use. It is a federally listed threatened species of the United States. This is an erect perennial herb growing up to a meter tall. It is "a rather handsome milkweed" which "is a very distinctive species with no obvious close relatives," according to Holmgren and Holmgren,

Viola frank-smithii is a rare species of Violet known by the common name Frank Smith's violet. It is endemic to Utah in the United States, where it is known only from Logan Canyon in the Bear River Range in Cache County. This perennial herb produces a stem few centimeters long, which is surrounded by the withered leaves of previous seasons and new leaves, which are heart-shaped. The flower is pale purple except for the lowest petal, which is greenish. Blooming occurs in May and June. This plant grows on vertical limestone cliffs, often in spots shaded by Douglas-fir (Pseudotsuga menziesii),

Penstemon rhizomatosus is a rare species of flowering plant in the plantain family known by the common names Scheel Creek beardtongue and rhizome beardtongue. It is endemic to Nevada in the United States, where it occurs only in the Schell Creek Range of White Pine County. This plant was first described in 1998. It is a perennial herb growing up to about 28 centimeters in maximum height. The clusters of stems arise from a woody caudex and thick taproot. The leaves are lance-shaped and borne on winged petioles. They are up to 3.5 centimeters long including the petioles and are coated in short

Penstemon janishiae is a species of penstemon known by the common names Antelope Valley beardtongue and Janish's beardtongue. It is native to the northwestern United States in sections of Idaho, Oregon, Nevada and northwestern California, where it is a member of the flora in sagebrush, woodland, and pine forests. It is a perennial herb with several hairy upright stems reaching up to about 25 centimeters tall. The leaves are up to 6 centimeters long, many located around the base of the plant and several pairs along each stem. The inflorescence produces several wide-mouthed tubular flowers 2 to

Castilleja kaibabensis is a species of flowering plant in the family Orobanchaceae known by the common name Kaibab Plateau Indian paintbrush. It is endemic to the Kaibab Plateau of Coconino County, Arizona, in the United States. Castilleja kaibabensis is a woody perennial herb with hairy stems and hairy, lance-shaped leaves. The inflorescence contains hairy bracts in shades of yellow and orange. The bract color is variable within and between populations. The bracts are divided into lobes, a characteristic that can help identify the plant. Blooming occurs in July. Castilleja kaibabensis grows

Castilleja christii is a rare species of flowering plant in the family Orobanchaceae known by the common name Christ's Indian paintbrush. It is endemic to Idaho in the United States, where there is a single population on Mount Harrison in the Albion Mountains in the Minidoka Ranger District of Sawtooth National Forest. It is one of Idaho's rarest plants. This plant was named for John Henry Christ (1896–1973), who first collected it. It is a perennial herb with a cluster of several erect stems 15 to 30 centimetres (5.9 to 11.8 inches) tall. The lance-shaped leaves are a few centimeters long

Primula capillaris is a rare species of flowering plant in the primrose family known by the common name Ruby Mountains primrose, or Ruby Mountain primrose. It is endemic to Nevada in the United States, where it is limited to the Ruby Mountains of Elko County. This small plant is a few centimeters tall, growing from a short rhizome. The thick, hairless leaves are linear or somewhat lance-shaped, 1 to 6 centimeters long and no more than half a centimeter wide with rounded tips. The delicate, showy flower has a bell-shaped calyx of green sepals. The corolla is reddish or bluish purple with a

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Penstemon pahutensis is a species of penstemon known by the common name Pahute Mesa beardtongue, or simply Pahute beardtongue. It is native to the desert hills and mountains of southern Nevada, including the Pahute Mesa for which it is named. It can also be found in a few areas over the border in California. It is a perennial herb growing up to 35 centimeters (14 in) tall. The paired, narrow leaves are linear to lance-shaped and up to 10 centimeters (4 in) long. The inflorescence bears blue-purple flowers up to 3 centimeters (1+1⁄4 in) long. The inside of the wide mouth of the flower is lined

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Castilleja salsuginosa is a species of flowering plant in the family Orobanchaceae known by the common name Monte Neva Indian paintbrush. It is endemic to Nevada in the United States, where it is known from two populations, one in White Pine County and another in Eureka County. The two occurrences of this plant are located about 83 miles (134 km) apart within the Great Basin. There are only about 275 individuals. This plant grows in two locations in Nevada's alkaline meadows. It grows around hot springs on salty, wet soils. The local elevation is about 6,000 feet (1,830 m). Other plants in

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Nevada holmgrenii is a flowering plant in the mustard family, Brassicaceae, endemic to Nevada in the United States. It is the only species in the genus Nevada. It was first described as Smelowskia holmgrenii.

Castilleja ecuadorensis is a species of plant in the paintbrush genus (Castilleja), part of the broomrape family (Orobanchaceae). It is endemic to Ecuador where it grows at very high elevations, above 3,000 meters, in wet meadows. It was only scientifically described as a species in 1984.

Castilleja aquariensis is a species of flowering plant in the family Orobanchaceae known by the common name Aquarius Plateau Indian paintbrush. It is endemic to Utah in the United States, where it occurs on the Aquarius Plateau, including Boulder Mountain. All occurrences are within the bounds of Dixie National Forest. This perennial herb grows 15 to 30 centimeters tall and blooms in inflorescences with small flowers and large light yellow bracts. It is probably "somewhat parasitic." This plant grows in sagebrush-grass meadows in subalpine climates and openings in stands of spruce. The soils

Potentilla cottamii is a rare species of flowering plant in the rose family known by the common names Cottam's cinquefoil and Pilot Range cinquefoil. It is native to Nevada and Utah in the United States. It occurs in the Pilot Range of Elko County, Nevada, and a small area of adjacent Utah. This plant was first described in 1987. It is a perennial herb which forms a mat of leafy herbage around its caudex. The leaves are each divided into three toothed leaflets. The flowers often have five petals, but sometimes only four. They are oval or somewhat triangular in shape, 3 or 4 millimeters long,

Potentilla angelliae is a rare species of flowering plant in the rose family known by the common names Angell cinquefoil and Boulder Mountain cinquefoil. It is endemic to Utah in the United States, where it is known only from Boulder Mountain on the Aquarius Plateau. This plant was first described in 1987. It is a perennial herb with spreading or prostrate stems up to 11 centimeters long. Each leaf is divided into a few lobed or toothed leaflets. Yellow flowers bloom in July. There are five known occurrences of this plant, with an estimated total of 19,000 individuals. The plants grow in a

Penstemon navajoa is a rare species of flowering plant in the plantain family known by the common name Navajo Mountain beardtongue, or Navajo beardtongue. It is endemic to Utah in the United States, where it is known only from San Juan County. This perennial herb reaches 20 to 40 centimeters in maximum height. It produces blue flowers with white beards, blooming taking place in July and August. It grows in open areas in coniferous forest habitat. There are only five known occurrences of this plant, mainly high on Navajo Mountain within the Navajo Nation. It may face threats from wildfire and

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Mentzelia memorabilis, the nine-eleven blazingstar, is a shrub-like perennial endemic to the Uinkaret Plateau in Mohave County Arizona and adjacent Washington County Utah. This is a species of conservation concern throughout its range. Nine-eleven blazingstar can be found between 1400 and 1700 m in elevation growing on gypsiferous outcrops of the Harrisburg formation.

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