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     Phlox canescens (formerly Phlox hoodii subspecies canescens) and Phlox austromontana are so similar that despite the supposed distinguishing characteristics listed immediately below, I find it very difficult to separate the two species in the Four Corners area.

     Most floras agree that a key to separating the two species is the structure of the intercostal membrane (the tissue that joins the calyx lobes). The membrane of P. canescens is flat or wrinkled but not keeled (like the keel of a boat), but the intercostal membrane of P. austromontana is strongly keeled. One caution: I have found P. canescens that has no intercostal membrane and the type specimen and the drawing of the type in Harvard's Gray Herbarium do not seem to show an intercostal membrane. The type specimen is in the center of the herbarium sheet with the drawing below it.

    A second helpful characteristic is that P. canescens' calyx, especially in the intercostal region, is usually quite hairy (see below) and the calyx of P. austromontana usually lacks hairs. (But notice that the calyces of P. austromontana shown in the first photograph below are hairy.)

     P. canescens is generally a smaller plant in all regards.  Its floral tube ranges from 8-12 mm long versus 8-18 mm long for the tube of P. austromontana and its leaves range from 6-10 mm long and 1-2 mm wide versus 8-15 mm long and 1-2 mm wide. Since the measurements overlap, they are often not helpful.

    The leaves of P. canescens are usually more densely clustered along the stem, but since the leaves of both species are densely clustered, this characteristic is only helpful if one has both species in hand.

    Stanley Welsh, Utah flora expert, separates the two species in his key on the basis of hairiness: P. canescens is "more or less softly woolly-tomentose, the tomentum white". P. austromontana is "variously hairy to glabrous, but not woolly or tomentose".

    William Weber separates the two species in his key on the basis of their growth pattern:   P. canescens is "cushion-like or densely caespitose; leaves crowded.... Leaves only slightly cobwebby".   P. austromontana is "loosely branched or matted; leaves not crowded". Unfortunately the terms "cushion-like", "caespitose", and "matted" are used interchangeably by many floras. I don't find these terms helpful.

    Click for Bill Jennings' key to Phlox. See if it helps you identify the various species of this beautiful genera. Do note that Bill indicates, "separation of Phlox hoodii [i.e. Phlox canescens] from Phlox austromontana is difficult in Montezuma County".

     "Phlox" is Greek for "flame"; some members of the Phlox genus are hot pinks and reds.  Linnaeus named this genus in 1753.

Phlox austromontana

Phlox austromontana

Phlox austromontana

Phlox austromontana

Phlox austromontana

Phlox austromontana (Southern Phlox)
Polemoniaceae (Phlox Family)

Semi-desert, foothills. Canyons, shrublands. Spring.
Above and left: Pyramid Trail, Red Rock Park, Gallup, New Mexico, May 2, 2015.

Phlox austromontana, from two to four inches tall, spreads in dense, low mats.  It is common to find dozens of patches of Phlox austromontana brightening a sandy, barren area.  Phlox austromontana has tiny, stiff, and sharp leaves which are often a lighter green than those of its close cousin, P. canescens.  The two plants are very similar and, in fact, detailed botanical descriptions in various floras attribute opposite characteristics to the two species. For a comparison of the characteristics of the two plants, see the top of this page.

Flowers are almost always entirely or primarily white, but tinges of pink are fairly common. I found the white and pink specimens shown above within a few feet of each other.

As mentioned at the top of this page, the two species of Phlox shown on this page, are said to be distinguished from each other by their intercostal membranes, the area between the thin green calyx lobes. The arrows in the second photograph at left point to this almost white area. In P. austromontana this area is usually glabrous and keeled, i.e., arched outward. The light color is evident in the photographs at left but although the keel is there it cannot be seen in these photographs. Also, if you look carefully, especially at the tip of the right arrow, you can see that the intercostal membrane on these plants is slightly hairy. Look at the last two photographs on this page and you will see that the intercostal membrane of Phlox canescens is very hairy.

Coville named this species in 1893 from a specimen collected by Marcus Jones in 1880.  "Austro" is Latin for "southern" and thus the species name means "of the southern mountains".

Phlox austromontana

Phlox hoodii

Phlox austromontana and Phlox canescens  (Phlox)
Polemoniaceae (Phlox Family)

Semi-desert, foothills. Canyons, shrublands. Spring.
Mud Springs Trail west of Cortez, April 15, 2010 and
Canyons of the Ancients National Monument, April 19, 2007.

Leaves of P. austromontana (upper photograph) are often lighter green, a bit longer, and more abruptly pointed than those of P. canescens (lower photograph).  Leaves of both plants are stiff and prickly.

 

 

Phlox canescens

Phlox canescens

Phlox hoodii

Phlox hoodii

Phlox hoodii

 

 

 

 

Phlox canescens. Synonym: Phlox hoodii subspecies canescens (Gray Phlox)
Polemoniaceae (Phlox Family)

Semi-desert, foothills. Canyons, shrublands. Spring.
Above: Carpenter Natural Area, April 25, 2016 and
Mud Springs Trail west of Cortez, April 2, 2017.
Left: Canyons of the Ancients National Monument, April 19, 2007 and April 9, 2012.

See the discussion about Phlox canescens at the top and bottom of this page.

Phlox canescens was named by Torrey and Gray in 1857 from a collection made by E. G. Beckwith in 1853 on the Pacific Railroad Survey. This species has often been termed Phlox hoodii variety canescens, but now, as the maps below indicate, P. hoodii is considered the species ranging northward into Canada from central Colorado. Only P. canescens is in the Four Corners region.

"Canescens" is from the Latin for "becoming gray", usually referring to a coating of hairs.

John Richardson collected Phlox hoodii in Saskatchewan on the 1819-1822 Franklin Arctic Expedition, and Richardson named and described the new species in 1823. The name honors his Expedition companion, Robert Hood, map maker and artist. (Click for more biographical information about Hood.)

Torrey and Gray named Phlox canescens in 1857 from a collection made in Utah in 1854 by Edward Beckwith, who was John Gunnison's Assistant Commander on the Pacific Railroad Survey of 1853 and who succeeded Gunnison from late 1853 to 1857 as Commander of the Survey after Gunnison and seven other members of his crew were massacred in Utah on October 26, 1853.

Click to view the type specimen of Phlox canescens collected by Beckwith and now preserved in the Kew Gardens Herbarium. Notice that the herbarium sheet contains three collections of this species. Beckwith's type is the small collection in the center of the sheet. Notice also that the date of the collection is not specified.

Also click to see a drawing (made by Torrey or Gray?) and a part of the type specimen housed in Harvard's Gray Herbarium.  

Phlox canescens

Phlox canescens

Phlox canescens. Synonym: Phlox hoodii subspecies canescens (Gray Phlox)
Polemoniaceae (Phlox Family)

Semi-desert, foothills. Canyons, shrublands. Spring.
Mud Springs Trail west of Cortez, April 2, 2017.

In the top photograph at left the arrow points to one of the long, thin, green calyx lobes.

In  the second photograph the red arrow points to the mass of hairs that grows between the lobes. The hairs in this area are diagnostic in separating P. canescens from P. austromontana, which has few if any hairs between its calyx lobes.

As mentioned at the top of this page, the area between the lobes (known as the "intercostal membrane") is usually strongly keeled in Phlox austromontana but it is said to be flat or wrinkled in Phlox canescens. Interestingly in the plants shown at left there is no intercostal membrane, i.e., the long calyx lobes are not connected to each other at their sides, only at their base.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Phlox austromontana

Phlox canescens

Range map for Phlox canescens  

Phlox hoodii

Range map for Phlox hoodii