''Penstemon virens'', commonly known as blue mist penstemon, Front Range beardtongue, or Green beardtongue, is a common '' Penstemon'' in the Front Range foothills in Colorado and Wyoming. The dainty flowers are an ornament to many rocky or sandy area within its range. It is confusingly similar to ''

Penstemon humilis ''Penstemon humilis'' is a species of flowering plant in the plantain family known by the common names low beardtonguePenstemon albertinus'' though the ranges of these plants do not overlap in the wild. The common name, blue mist penstemon, refers to the cloud of flowers on multiple stems facing every direction.

Description

''Penstemon virens'' has flowering stems are typically 10–40 cm in height and stand upright with very little curve. The stems are covered in extremely fine and short hairs that increase to being glandular and hairy closer to the buds and flowers, but are rarely almost or completely hairless. Most of the leaves are at the base of the plant and relatively short, 2–10.2 cm long. These

basal leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

are bright green, smooth, shiny, and have smooth or very finely toothed edges ( denticulate margins). Though smooth, the leaves are not leathery or thick, and are oblanceolate to spatulate with a tapered base and 4–15 mm in width. The end of the leaves are mildly pointed, ranging from obtuse to

acute Acute may refer to: Science and technology * Acute angle ** Acute triangle ** Acute, a leaf shape in the glossary of leaf morphology * Acute (medicine), a disease that it is of short duration and of recent onset. ** Acute toxicity, the adverse eff ...

. The leaves attached to the flowering stems are also hairless, have smooth leaf edges, lancelolate to slightly ovate in shape, and shorter than the basal leaves, 1.8–5 cm in length and 3–14 mm wide. The form of the plant is a low, spreading mat that enlarges each year, with leaves that persist over the winter in most locations. The flowering stem is a thyrse, it grows without a genetically determined limit, but instead stops due to environmental conditions. It will typically have 3-6 clusters of flowers on the stem just above each leaf pair. Close examination will show that the flower clusters are actually paired groups on opposite sides of the stem (a

verticillaster An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed on ...

), but they will face in every direction. The flowers of ''Penstemon virens'' have five green, glandular-pubescent sepals at the base of the flower that are ovate to lanceolate, 2–4.5 mm long and 1.5-2.5 mm wide at the base. The edge of each sepal is edged with red. The flower is a tapered funnel 10–16 mm long and pale sky blue to light purple or violet. The flower divides into five rounded petals at its front and has purple-blue to reddish-purple nectar guides from the center of each petal leading down into the flower. The outside of the flower is glandular-pubescent and on the inside has moderate amount of fine white fuzz on the inside of the flower. The throat of the flower tube has an inside diameter of 3–5 mm, about 4–5 mm on the outside. The lower lip and just inside the tube will have a few white longer hairs. The infertile fifth stamen, the staminode for which the genus is named, is a hairy golden-brown, and 8–10 mm long. It will almost reach the end of the flower tube. The four fertile stamens are paired above, curve inwards and upwards, and are purple to pink-white. The style is 8–11 mm long. The seed capsules are small tear drop shapes about 5–7 mm long and 2–3 mm wide and are ripe towards the end of July or the beginning of August at lower elevations.

Taxonomy

Penstemon_virens_herbarium_specimen_1915_Wyoming

The first recorded collection of ''Penstemon virens'' was by

Francis W. Pennell Francis Whittier Pennell (4 August 1886 – 3 February 1952) was an American botanist best known for his studies of the Scrophulariaceae. Employed by the New York Botanical Garden and then by the Academy of Natural Sciences of Philadelphia, he carri ...

on 9 June 1915 on Ute Creek north of Manitou Springs, CO. On the same trip he collected at least two more specimens from Colorado and two from locations in Wyoming, with the type specimen collected 13 June on a hillside west of Morrison, CO. The famous Swedish-American botanist

Per Axel Rydberg Per Axel Rydberg (July 6, 1860 – July 25, 1931) was a Swedish-born, American botanist who was the first curator of the New York Botanical Garden Herbarium. Biography Per Axel Rydberg was born in Odh, Västergötland, Sweden and emigrated to t ...

published a description that credited Pennell for the description in his book ''Flora of the Rocky Mountains and Adjacent Plains'' in 1917. However, Rydberg is now credited with making formal description. The name of the species, "virens', is the present active participle of the Latin word vireō (“I am green”).

Habitat and distribution

''Penstemon virens'' is commonly found growing on rocky slopes, on rock outcrops, in forest openings, along road cuts, and other disturbed areas. They grow from 1600 to 3000 m in elevation. ''Penstemon virens'' is common in its habitat, but not widely distributed. Plants are found on the Medicine Bow Range in southeastern Wyoming south to

Culebra Range The Sangre de Cristo Mountains (Spanish language, Spanish for "Blood of Christ") are the southernmost mountain range, subrange of the Rocky Mountains. They are located in southern Colorado and northern New Mexico in the United States. The mountains ...

in southeastern Colorado. It is common in the mountains and foothills of the Front Range in between and also on the Palmer Divide in Colorado. It is recorded by the USDA

Natural Resources Conservation Service Natural Resources Conservation Service (NRCS), formerly known as the Soil Conservation Service (SCS), is an agency of the United States Department of Agriculture (USDA) that provides technical assistance to farmers and other private landowners an ...

PLANTS database (PLANTS) with county level records in Colorado and Wyoming.

Ecology

''Penstemon virens'' tend to grow together in large numbers rather than singly or scattered throughout the landscape, rarely fewer than 10 plants in a population. Most species observed visiting and entering the flowers of ''P. virens'' are bees. The most frequent visitors are members of genus ''

Lasioglossum The sweat bee genus ''Lasioglossum'' is the largest of all bee genera, containing over 1700 species in numerous subgenera worldwide.Gibbs, J., et al. (2012)Phylogeny of halictine bees supports a shared origin of eusociality for ''Halictus'' an ...

'', but genus ''

Osmia Mason bee is a name now commonly used for species of bees in the genus ''Osmia'', of the family Megachilidae. Mason bees are named for their habit of using mud or other "masonry" products in constructing their nests, which are made in naturally ...

'', genus ''

Bombus A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related gener ...

'', and honeybees also frequently visit them. Specific species observed include ''

Apis mellifera The western honey bee or European honey bee (''Apis mellifera'') is the most common of the 7–12 species of honey bees worldwide. The genus name ''Apis'' is Latin for "bee", and ''mellifera'' is the Latin for "honey-bearing" or "honey carrying", ...

'', ''

Augochlorella aurata ''Augochlorella aurata'' is a species of Halictidae, sweat bee (bees attracted by the salt in human sweat) in the family Halictidae. It is found in North America east of the Rocky Mountains. The body is a brilliant green metallic color, diffused ...

'', ''

Bombus huntii ''Bombus huntii'' is a species of bumblebee. It is native to western North America, where it occurs in western Canada and the United States as far east as Manitoba and Minnesota, and in Mexico as far south as the Trans-Mexican Volcanic Belt.Hatf ...

'', ''

Bombus rufocinctus ''Bombus rufocinctus'' is a species of bumblebee known commonly as the "red-belted bumblebee."NatureServe. 2015''Bombus rufocinctus''.NatureServe Explorer Version 7.1. Accessed 10 March 2016. It is native to North America where it has a wide dis ...

'', ''

Bombus centralis ''Bombus centralis'', the central bumblebee, is a species of bumble bee found in parts of Canada and the western United States. The species was first described by Ezra Townsend Cresson in 1864. Description ''Bombus centralis'' is a small bu ...

'', ''

Halictus tripartitus ''Halictus tripartitus'' is a species of sweat bee in the family Halictidae. It is partially eusocial, with nests connected underground and some workers capable of reproducing. References Further reading * tripartitus Articles created ...

'', ''

Hoplitis truncata ''Hoplitis'' is a genus of bees in the family Megachilidae. There are more than 380 described species in ''Hoplitis''. See also * List of Hoplitis species This is a list of 385 species in ''Hoplitis'', a genus of leafcutter, mason, and resi ...

'', '' Lasioglossum sisymbrii'', and '' Lasioglossum trizonatum''. They are also sometimes visited by beeflies (''

Bombyliidae The Bombyliidae are a family of flies, commonly known as bee flies. Adults generally feed on nectar and pollen, some being important pollinators. Larvae are mostly parasitoids of other insects. Overview The Bombyliidae are a large family of fl ...

'') and butterflies, but they have not been observed contacting reproductive parts and are thought to be necatar robbers. Hummingbirds, though present in the range, have not yet been scientifically observed visiting ''P. virens''.

Cultivation

Blue mist penstemons are recommended as garden plants by local governments, water providers, and extension services for areas in or near the Front Range. They are prized for their low water usage, adaptation to local climate, handsome blooms, long lifespan, and ease of cultivation. They are drought tolerant once established, but not adapted to constantly dry conditions. In garden settings they are adapted to full sun to partial shade conditions in the west and full sun in the east of the United States. They are quite adaptable to different garden soil conditions, but like all penstemons are healthier with good drainage. Their seeds require cold and moist stratification of six weeks at 4.5 °C for good germination rates or to be planted outside over the winter. The coldest USDA hardiness zones where this plant is known to survive is zone 4.

References

{{Taxonbar, from=Q17741164 virens Flora of Colorado Flora of Wyoming Plants described in 1917