Home | Next | Previous | Index | Purchase book

Idaho Mountain Wildflowers

The Phlox Family, Polemoniaceae  

The phlox family consists of twenty genera and 360 species. Most are found in North America although a few are native to temperate parts of South America and Eurasia. Many species in the family have been cultivated as garden ornamentals: phlox, Jacob’s ladder, gilias, and others. These represent the family’s only economic importance. Flowers in this family are usually clustered and sometimes form a head in which the upper flowers are the first to bloom (botanically, a “cyme”).  Five sepals and five petals unite at the base to form a flower tube. At the point that the petals become separate they flare outward , and the flowers then are variously referred to as being trumpet-, funnel-, or saucer-shaped (the latter are “salverform”). Fourteen genera of Polemoniaceae occur in the Northwest. At least half of these are represented in Idaho. The origin of the word “polemonium” is uncertain; several derivations have been suggested. It may be that the plant was named for Polemon, a second century B.C. Greek philosopher and one of of Aristotle’s successors as head of the Lyceum in Athens.

Spreading phlox, Phlox diffusa Benth. var. longistylis (Wherry) M. E. Peck (left). "Phlox" (ancient Greek for “flame”) was the name of a now unknown plant, and later given to our plants. Phlox diffusa, is common in our mountains, growing in clumps of narrow gray-green leaves surmounted by a profusion of white (usually), pink, or lavender flowers. Spreading phlox dots rocky slopes from early April at mid-elevations, well into the summer at timberline and higher. A rather similar species, Phlox hoodii Richardson, is common at lower altitudes.

Longleaf phlox, Phlox longifolia Nutt. (right). The longleaf phlox grows at all elevations, blooming from late in the spring well into the summer; depending on the altitude. The plant is taller, has narrower petals, longer leaves and less tightly clustered flowers than those of the spreading phlox. Nathaniel Wyeth (he of the wyethias) collected the original specimen in 1833 in Idaho or Montana, and his friend Thomas Nuttall described the species the following year.

Showy phlox, Phlox speciosa Pursh (left). The showy (speciosa) phlox grows at lower elevations than do those shown above, often growing with sagebrush in the foothills and lower mountains. It is more common in the northern half of Idaho. Lewis and Clark collected the plant on May 7, 1806, while in what today is Nez Perce County on their return journey. This is the only phlox in our area with prominently notched petals. The showy phlox makes a good garden ornamental.

Slender phlox, Microsteris gracilis (Hook.) Greene var. humilior (Hook.) Cronquist (right). The slender phlox (also classified as Phlox gracilis) appears in the spring, sometimes in large numbers. Its flowers may be pink or white. They are borne in pairs, although they do not always bloom at the same time. Typically the petals are notched at the end. Elliptical, opposed leaves become narrower and more pointed toward the top of the stem. The plant is only about two inches high, so single plants are easily missed. Its varietal name humilior means “low-growing” or “dwarf.” Microsteris was derived from the Greek mikros (small) and sterizo (to support, or prop up) evidently having to do with the plant’s small size.

Mountain navarettia, Navarretia divaricata (Torr.) Greene (left) grows fairly high in the mountains. This small, cactus-like plant's generic name, divaricatum, means branching, chosen because, uniquely, branches are given off from within the terminal leaf clusters. The plants grow in recently moist place, and with dry weather they become brown, prickly, powder-puff-sized ghosts of their former selves.

Brewer’s navarretia, Navarretia breweri (A. Gray) Greene (right). Brewer’s navarretia’s yellow flowers measure no more than 1/8 inch across. Typically, several flowers grow at the end of the stems, surrounded by needle-shaped leaves (navarretias are also known as “pin-cushion plants”). The genus was named for Francisco Fernandez Navarrete (d. 1689), a Spanish missionary, physician, and botanist. William Henry Brewer (1828-1910) was an associate of mineralogist Josiah Dwight Whitney (of Mt. Whitney) while surveying California (1860-1864) and later professor of agriculture at Yale.

Western Jacob’s-ladder, Polemonium occidentale Greene (left) is a moist-meadow and streamside plant a foot or more high that grows as high as the subalpine zone. It is closely related to an uncommon European alpine, Polemonium caeruleum and some botanists believe that ours is a variety of that plant. Furry stems are topped with small, five-petaled bright blue flowers. Prominent yellow anthers on long filaments add to the flower’s attractive appearance. The name Jacob’s-ladder reflects the plant’s feathery compound leaves, common to the genus. These give off a pronounced skunk-like odor when crushed; the smell may be the first indication that polemoniums are growing nearby

Showy polemonium, Polemonium pulcherrimum Hook. (right). Lewis and Clark collected a species of polemonium on the Lolo trail on June 27, 1806 believed  originally to be Polemonium occidentale. It seems more likely, however, that it was the showy polemonium, a common species along their trail on that date. While the plant shown here—photographed on a shady slope near Lolo Pass—has pale blue flowers, those growing in the open are often bright blue. The name, pulcherrimum, means “most beautiful.”

Sticky (also skunk) polemonium, Polemonium viscosum Nutt. (left). The sticky polemonium (or Jacob’s ladder) is an attractive, low-growing plant with deep blue flowers and pinnate leaves populated with small, tightly ranked leaflets. When crushed, this plant’s leaves give off a strong skunk-like odor—“skunk polemonium” is another common name. The plants grow in separate clumps and are found quite high; we have seen small specimens growing well above treeline.

Nuttall’s leptosiphon, Leptosiphon nuttallii (A. Gray) J. M. Porter & L. A. Johnson (right). This attractive plant (originally classified as Linanthastrum and more recently as Linanthus) is a common, summer- blooming wildflower that grows as high as tree-line. Typically, it forms discrete clumps. Its linear, alternate leaves are so close together that they appear to form separate rosettes on the plants’ woody stems. White, yellow-eyed flowers are five-petaled; each has five prominent anthers. Thomas Nuttall found the species, then new to science, near Fort Hall in 1834. The name Leptosiphon is a recently restored prior classification derived from the Greek; it means “slender tube” for the narrow flower tube.

Scarlet gilia, Ipomopsis aggregata (Pursh) V. Grant (left) The scarlet gilia (formerly Gilia aggregata) blooms in late spring, peaks in early summer, and lingers on into late summer. One cannot hike our trails without encountering its trumpet-shaped, bright red flowers. The flowers and foliage have an acrid odor when crushed, so “skunk-flower” is another name for the plant, although the odor really is not skunk-like. The name Gilia honors Italian naturalist and clergyman, Filippo Luigi Gil (1756-1821), Director of the Vatican observatory. The species name “aggregata” refers to the loose flower clusters. The present generic name, Ipomopsis means “morning glory-like.” Lewis and Clark collected the scarlet gilia—a plant hitherto unknown to science—while on the Lolo trail in north-central Idaho during their return trip (June 26, 1806).

Ball-head gilia, Ipomopsis congesta, (Hook.) V. Grant var. viridis (Cronquist) Reveal (right) Here is another gilia that has been reclassified as an Ipomopsis. The species name, congesta, reflects the plant’s round flower head, with its many tiny phlox-like flowers. It grows high in the mountains on dry sandy slopes, blooming in mid-summer. The leaves are silvery-green, usually with three linear leaflets, arising from a central branched woody stem. Nine varieties of this plant are recognized, classified mostly by the shape of the leaves.

Narrow-leaf collomia, Collomia linearis Nutt. (left). The narrow-leaf collomia's five-petaled flowers are about a quarter of an inch in diameter, with a long flower tube. The name linearis describes the plant’s narrow leaves; Collomia, from the Greek, means “glue,” because the seeds become mucilaginous when wet—a property that helps to identify plants in this family. This plant is so common in early spring that anyone hiking in our mountains will see it. Lewis and Clark were first to collect this plant (April 17th, 1806) at today’s The Dalles, Oregon, on their homeward journey. Frederick Pursh, who described the expedition’s plants, did not recognize their specimen as a new species and it remained for Thomas Nuttall to find it again.

Diffuse mountain-trumpet, Collomia tenella Gray (right). This collomia is blooms in late spring. Its white flowers are notable for their peculiar involucrum with its black markings and small "horned" projections (inset). The plant is covered with small hairs, best seen with magnification. Many of the hairs end in small pigmented glands that may cause all or part of the plant to appear black. This collomia grows in Idaho and surrounding states (excepting Montana).

Home | Next | Previous | Index | Purchase book